Throttle Cracker Tuning Question {B4309}

[pinstripebob]

Hi all,

I've gotten my tune in a pretty good spot. I've gotten rid of almost all my bucking, surging, hunting, and stalling issues after installing a big camshaft. I'm looking at the throttle cracker table now, B4309. I have attached my current tune and latest log where I was looking at this predefined map for B4309.

When tuning this table, can I do a log, open the B4309 map, then copy/paste it into my tune? That seems too easy. I've been able to manually adjust it where I have bucking issues, but if there's a way to add some automation to my life I'd like to try it.

I've gone through a couple idle tutorials, and neither mentions any adjustments besides making tweaks and trying them. I'm not opposed to this method, but if I can gather data and use that it might make life easier. Below are the tutorials I followed:
https://forum.efilive.com/showthread.php?4661-Idle-Tuning-Helpful-Info-Inside
https://forum.efilive.com/showthread.php?14439-Idle-Tips-amp-Tricks

I have a 2004 GTO with the 5.7, it has a fairly long duration cam (Summit part number SUM-8700, similar to the ASA cam of the day). It also has an over-the-radiator intake and full exhaust.

From the data log below, I applied a filter to only show operating temperature and no throttle input. Most of the cells in my B4309 map end up being 0.00 or near 0.00. My thinking was modifying the throttle cracker table with values where only the throttle cracker is active and the throttle follower isn't.

I've done RAFIG a few times and it's pretty spot on, the car fires right up and seems like it's getting the right amount of air. I shifted the IAC area table so IACDES_B and DYNCYLAIR are the same at operating temperature when idling prior to completing the RAFIG process.

Throttle cracker data log:
22558

Latest tune:
22559

[joecar]

I'm looking at this closer... do you have the previous .ctz file so I can see what you did.

[pinstripebob]

Not a problem! I have attached my stock tune below. The big changes are the camshaft and the air intake (not intake manifold).

I'm hoping I can get some direction on how to use the Throttle Cracker map in the scan tool, although any other pointers are appreciated!

Bone stock tune:
22572

[pinstripebob]

So I've been trying to do more research. From what I've gathered comparing my stock (or modified) GTO tune to a C5 or 4th gen, some of my airflow decay and/or delay tables are quite a bit different.

I've gone through the tutorials on this forum a few times. I think the next step I want to take is to run back through my spark tables to make sure those are in check. I found a base tune for an LS1-M6 (my combo) with a mild cam and some other minor bolt-ons. I found the tune here at the bottom of post #1: https://forum.efilive.com/showthread.php?14439-Idle-Tips-amp-Tricks&p=129525&viewfull=1#post129525

Looking at the base spark table, the commanded spark at idle is 1* off what I have, which makes sense. This tune also has much more timing below idle RPM, which would help prevent stalling.

Looking at post 1 of the idle tuning thread from SSpdDmn, seeing some of his posts and Swingtan's posts from a few years ago, the 4th gen F-body airflow tables are a solid place to start. I haven't seen anyone say that about the GTO tune, so I'm a little suspect of it. I have heard negative things about Holden tunes, again adding to my suspicion. SSpdDmn's throttle cracker table is set to 0 around the RPMs where I have some bucking (I'm chasing low-speed driveability right now). Here's his thread: https://forum.efilive.com/showthread.php?4661-Idle-Tuning-Helpful-Info-Inside

So I'm inclined to do the following:
1. Try the base spark table from the LS1-M6 base tune, go for a drive and see how it goes.
2. Copy the throttle cracker/follower and their decay/delay tables from that same tune, go for a drive and see how that goes.

Thoughts on that?

[statesman]

I have heard negative things about Holden tunes, again adding to my suspicion.

Yeah, as a Holden owner I can confirm that the stock Holden tunes suck. But let's not dwell on the negatives, lets look at the positives... Holden tunes have left plenty of room for improvement. :laugh:



So I'm inclined to do the following:
1. Try the base spark table from the LS1-M6 base tune, go for a drive and see how it goes.
2. Copy the throttle cracker/follower and their decay/delay tables from that same tune, go for a drive and see how that goes.

Thoughts on that?

Just blindly trying things out is sometimes a good thing (when you see the effect of changing tables, it can help you to learn about those tables)... but remember to always log for KR.

[Doc]

Consider the basics, Throttle Cracker is controlling the IAC valve when you are on the throttle. Throttle Follower is controlling the IAC valve when you are off the throttle. So my first question is in what condition, on throttle or off throttle or both is when the trouble is happening? Next thing to consider is the minimum timing table. What are your low crusing #'s in the minimum timing table. You have to think about this process like leveling a tripod. Air/Fuel/Spark have to be balanced. If one of the three is right but one of the other two are off base you will find the outcome you are describing. I take it you have already performed AutoVE on the MAP and MAF? That's a good start. When scanning the trouble spots keep a keen eye on IAC, Fuel Trim, and Timing.

[pinstripebob]

Statesman, good call on checking for knock! I've been monitoring KR and had to lower a few areas of my high/low octane spark tables.

Doc, seeing that written out and reading it helps out. I think I've gotten a bit of tunnel vision going after the throttle cracker and follower tables. I'm trying to get my low RPM/low load bucking to go away. The condition exists under 2,000RPM, in gear, under light throttle OR under no throttle. So throttle cracker and follower should need some attention.

I've been cruising around 34.5-35.0 degrees, although now that you ask and I look at my log/tune side by side it looks like I should be at 36.89 at .28g/cyl and 1800 RPM (frame 2460 in the log). Although, the spark table does some interpolating between cells, right? Minimum spark advance is still stock, about -12 or -6 at cruising speed/RPM.

I have done CALC.VET and gotten my MAF pretty well dialed in. My fuel trims aren't bad, but my wideband sensor died before I could do more VE table tuning. I got a new sensor, hopefully I can get it put in this weekend.

From my last post, I've done the following:
1. Modified my base spark table, bumped up idle spark a degree, bumped up 600/400RPM cells quite a bit to act as a stall saver (engine liked to try dying doing parking lot maneuvers).
2. Reduced high/low octane tables any time I logged knock.
3. Reduced throttle cracker cells 5% at a time whenever there was bucking and I was off throttle. Also bumped up 400RPM cells to act as a stall saver.

I should note that bucking is GREATLY reduced at this time. I'm a pretty happy camper, it seems like I'm moving in the right direction. I suppose there aren't any good uses for EFILive's preconfigured throttle cracker and follower maps in the scan tool?

Current log, city/highway/city driving:
22578

Current tune that generated the above log:
22579

[statesman]

There's not enough in that log for me to see what's happening.

Do another log. Log all the things you logged last time and add these PIDs...

GM.IAC
GM.VOLTS
GM.MAFFREQ
SAE.SHRTFT1
SAE.SHRTFT2

And yeah, I don't care if you blow the 24 channel count.

[pinstripebob]

So many channels!!

I should be able to snag a log on my way in to work, no problem.

Sent from my Pixel 3 using Tapatalk

[Doc]

Don't forget to pay attention to the timing as well. Remember the fire triangle. Especially in the low cruising areas you have mentioned. Stock timing cells are pretty high for a bigger cam.

[pinstripebob]

I got a log with the PIDs in my last log and the ones you wanted, Statesman.

I looked at it a bit, I'm at lunch now. Frame 3950 is a pretty good spot to look at for what I'm trying to smooth out. I let off the throttle on the highway and coasted for a bit. My RPM was nice and smooth around frame 3833, then around 3950 it started bucking. Timing is steady at 24*, IAC is steady, but my STFTs start to creep up. I did get my new wideband sensor, my goal is to get that in the car this weekend so I can get back on tuning fueling.

Doc, I did copy the lower airflow portion of the B5913&B5914 tables from the ASA tune in the tune DropBox (what used to be holdencrazy.com). From what I found, the ASA cam that Speedway Motors sells has almost identical specs to my cam, Summit's SUM-8700. That lead me to believe that, along with some threads I've read that big cams need more advance, the tables in the ASA tune should work well for my setup. Since I'm off throttle, my timing goes back to my base spark table, and like I said in the previous paragraph this is 24* off throttle at speed.

Any other thoughts? My tune and its log from this morning are below. Thanks for the help, by the way!

Tune:
22581

Log:
22580

[statesman]

I'm making some changes to your fueling... most notably, your injection timing. You were spraying really late... this is unwarranted with your cam.

Do a log for me with exactly the same pids you logged last time... and make a note of where it's bucking (like you did last time).

[pinstripebob]

I finally got a good log. I flashed your tune Statesman, and got my wideband fixed and included its PIDs as well in this log.

All my injector tables are still stock, but it seems like your tweaks helped out. I notice less bucking when off throttle in general.

Here are a few places to look in the log:

On throttle bucking:
1. Frames 3100-3128, IAC is steady, STFT aren't bad, LTFT are about -9% which shows room for improvement.
2. Bad around frames 5435-5450, STFT goes from positive to negative, WO2 goes lean/rich/lean, IAC steps are steady but seem to suddenly increase midway through this portion of the log and plateau.

Off throttle bucking:
1. Frames 5154-5302, IAC is steady, STFT average around 1%, LTFT is around -4.5%, spark is steady, WO2 average is a hair lean. I'm decelerating in gear smoothly, then I get the herky jerkies.
2. Frames 6446-6501, IAC is steady, STFT are rich then go a bit lean, LTFT is about -3%, WO2 is rich then goes a bit lean. Same RPM action as above.
3. Frames 7347-7431, IAC is steady, STFT goes rich then bounces rich/lean, LTFT looks fine, WO2 has a couple lean spikes, RPM does the same as above.

Later in the log there are a couple more areas where WO2 shows a couple lean spikes, but the spots in the log above are good examples of the bucking I'm getting.

Log:
22583

[statesman]

All my injector tables are still stock, but it seems like your tweaks helped out. I notice less bucking when off throttle in general.

Stock injector data isn't always the best injector data.



1. Frames 3100-3128, IAC is steady, STFT aren't bad, LTFT are about -9% which shows room for improvement.

I'm not overly concerned with some wild trims in that log. The first change was just a 'rough cut'... it was never meant to be perfect, it was just to straighten a few things out so I can see what's going on a bit better. The changes I'm making now should start to bring your fueling back into line.

Do a log on this tune file like you've been doing... but try taking the long way home next time, so I get a bit more of the log at full operating temperature. Taking such detailed notes of where it's bucking saves me a lot of time, so try to do the same again.

[pinstripebob]

Statesman, your changes do seem to be working well! It's too bad stock data isn't always the best, but the improvements are great!

I flashed your tune and took some country roads home. Unfortunately one that I chose was pretty low speed, but I think overall I got good data. Overall the car seems smoother, bucking is greatly reduced off throttle. There is still some under light throttle.

Below are the areas where I noticed this bucking. Thanks for looking into this and helping out! I'm enjoying going through and noting areas of concern, so if that helps you I'll keep doing it.

Unfortunately, I must have gotten comfortable and selected the wrong PIDs! I'm missing IAC, voltage, and STFT data. Sorry about that! I should be able to get another log tomorrow WITH those PIDs, if not tomorrow then probably Monday or Wednesday. If this log doesn't help and we need the STFT/voltage/IAC data, that's not a problem, I'll get a log with the correct PIDs. I did some steady throttle pulls as well in case that helps.

Coasting in gear, no throttle, no bucking:
Frames 4996-5130

Coasting in gear, no throttle, some bucking toward end:
General note, off-throttle bucking is almost gone. Comes on around 1100RPM, but if I stab the clutch the engine seems to be idling around that RPM anyway.
Frames 5385-5836. WO2 looks good, LTFT are a bit off but seem okay in the bucking and pre-bucking area. Spark looks steady/smooth. This has the worst off-throttle bucking of the log, but it wasn

[pinstripebob]

wasn’t bad and was at a pretty low RPM.
Frames 6032-6454. WO2 looks fine, maybe a bit lean in general but not bad. Spark is smooth, had very light bucking around 1100-1050 RPM.
Frames 10677-10825. WO2 looks okay, LTFT are fine, spark is smooth. RPM was low, bucking was probably caused by the throttle cracker, just my guess.
Frames 15626-15733. I was using throttle, lowered throttle, then went off throttle. Off throttle bucked the whole time, might be a good little area to look at in the log. WO2 went rich then lean, might be an indicator of the cause.
Frames 16764-16940. WO2 looks okay, LTFT are fine, spark is smooth. RPM was low, bucking was probably caused by the throttle cracker, just my guess.

Light throttle in gear, some bucking:
Frames 8424-8583, WO2 looks alright, spark is smooth, LTFT isn’t bad.
Frames 8772-8973, WO2 looks alright, spark is smooth, LTFT is low, RPM is around 1350.
Frames 9148-9222, I think I shifted into 5th or 6th gear here and had some rough bucking. Spark actually got choppy around frame 9200.
Frames 12868-13276, WO2 looks fine, spark is smooth, LTFT look great, had some RPM choppiness with a spot of rough chop near frames 13181-13199.
Frames 13550-13769, I think I was going up a hill in a higher gear and kept TPS low with some bucking. WO2, LTFT, and spark advance look alright.


NOTE: I'm not sure why I can't fit all of this in one reply.

[joecar]

Forum web software seems to somtimes truncate responses.

[statesman]

Overall the car seems smoother, bucking is greatly reduced off throttle.

The engine will run smoother as the tune gets better... that's normal.



Unfortunately, I must have gotten comfortable and selected the wrong PIDs! I'm missing IAC, voltage, and STFT data. Sorry about that! I should be able to get another log tomorrow WITH those PIDs, if not tomorrow then probably Monday or Wednesday. If this log doesn't help and we need the STFT/voltage/IAC data, that's not a problem, I'll get a log with the correct PIDs. I did some steady throttle pulls as well in case that helps.

Yeah, that log is useless to me.... I need you to log everything that I asked for.

[joecar]

Double check your pids.

[pinstripebob]

Alright finally got a log and had time to sift through it. Car has been pretty consistent, so no new notes. Overall it's smoother, bucking off throttle is mostly gone, bucking under 5% TPS is still there but not as often. ECT hits 80C at frame 700, pretty early in the log. Below are the areas where I logged bucking:

On throttle bucking:
Frames 1338-1446, STFT goes a bit positive, LTFT are about -6.5, everything else looks fine, some bucking here but it isn

[pinstripebob]

On throttle bucking:
Frames 1338-1446, STFT goes a bit positive, LTFT are about -6.5, everything else looks fine, some bucking here but it isn’t terrible.
Frames 2654-2697, bucking is pretty bad, lower TPS seems to cause worse bucking, STFT are a bit negative but everything else looks good.
Frames 2844-3029, some bucking but it isn’t terrible, everything looks fine, STFT may be a bit negative.
Frames 4409-4707, some bucking, STFT are a bit negative, everything else looks fine.
Frames 5241-5292, bad bucking, STFT are negative, IAC steps makes a big jump in the middle of it. My TPS changed a tiny hair, might have caused the IAC change.
Frames 7118-7202, slight bucking, have the same IAC change as above. Looks like another tiny TPS change, probably the cause of the IAC change.
Frames 8546-8636, bad bucking, STFT start pretty negative then become less negative, everything else looks fine.
Frames 8834-9138, some bucking, everything looks pretty good, STFT are a bit negative but not bad. STFT2 goes positive.
Frames 9389-9748, a little choppy, everything looks pretty good.
Frames 10190-10299, a little choppy, WO2 is a little lean, STFT are negative at first but then look pretty good. First bit of STFT negativity is opposite first bit of LTFT positivity.
Frames 10562-10665, a little choppy, WO2 is a bit lean, everything else looks good although the rapid IAC change occurs.
Off throttle bucking:
Frames 1916-2036, STFT are trending positive when bucking starts, LTFT is okay, WO2 is biased lean, car is smooth then has a but of bucking starting at about 1230RPM, not terrible though.
Frames 22371-2498, pretty much the same as above.

Again thanks for the help! I'm wondering if I need to spend more time adjusting the VE table via CALC.VET? Below is the log:

[statesman]

Your fueling isn't pulling in as nicely as it should be. I ran some diagnostics on your log and found lower than expected airflow readings with low MAP values. This could indicate a possible air leak in your intake manifold. Check for air leaks and fix any leaks you find before doing your next log. A smoke test of your intake would be ideal, but if you can't manage that then just check for broken or split air hoses and run the engine at idle and listen for any hissing sounds.

Log the same PIDs as usual... and make sure you log ALL of them.:bangin:

[pinstripebob]

I checked for vacuum leaks Wednesday night. I couldn't hear anything, I wiggled all hoses and couldn't get the engine to change speed or make weird noises. I sprayed every spot with a seal or hose with carb cleaner and didn't experience any changes. The engine has a fair number of miles on it, but I couldn't find any potential vacuum leaks.

I did get another log. Don't worry, I saved all your required PIDs to Statesman.pid the last time I logged! :good:

ECT hits 80C around frame 1800. Below are some notes. Overall nothing has gotten worse, I did notice more improvement with low TPS and low RPM bucking still being reduced a bit.

Steady throttle pull:
Frames 2083-2152
Frames 3519-3590

Low TPS bucking:
Frames 2359-2449
Frames 2866-2922
Frames 4749-4811
Frames 5020-5085

Steady throttle cruise:
Frames 2603-2853
Frames 3196-3412
Frames 4084-4403
Frames 10992-11095
Frames 12187-12302

Off throttle deceleration with bucking:
Frames 3006-3181
Frames 4412-4438
Frames 9973-10015

Here is the log file:

22598

[statesman]

I checked for vacuum leaks Wednesday night. I couldn't hear anything, I wiggled all hoses and couldn't get the engine to change speed or make weird noises. I sprayed every spot with a seal or hose with carb cleaner and didn't experience any changes. The engine has a fair number of miles on it, but I couldn't find any potential vacuum leaks.

Okay. I'll have to hunt down the reason that the numbers don't look quite right.

A few questions for you....

Have you recently (or ever) cleaned your MAF sensor?
Are you using an oil impregnated air filter (like a K&N)?
Is your intake tubing stock or modified?

We'll keep working on your bucking while I'm trying to figure out why your fueling doesn't want to straighten out.

[pinstripebob]

Let me know what you think. I don't have a problem doing some troubleshooting.

To answer your questions:

1. I have cleaned it, I think the last time I cleaned it was 3 or 4 months ago. It's a stock replacement from AutoZone, maybe 3 years old.
2. I use a Green brand filter that is oiled. I'm very careful when I oil it, and the last time I cleaned/oiled it I cleaned the MAF sensor after driving for a couple weeks.
3. My intake tubing is modified. I've read you should have 6" before/after the MAF of straight pipe, which I don't. Below is a picture of my bay (red car) versus a stock bay (yellow car).

I'm still wondering if my VE table needs more work, maybe that would help us out? MAF seems to be in fairly good shape. I've done a couple CALC.VET logs and the correction factor to the MAF curve is never more than 2%.

Mine:
22604

Stock:
22605

[statesman]

I'm still wondering if my VE table needs more work, maybe that would help us out?

No, we're in MAF only mode so the VE doesn't come into play. Leave the VE table until we get the fueling right.

Alright, now I see why I got those numbers when I analyzed your log.

Do a log with the tune file I posted... fueling will still be out, but I'm more interested in your low throttle bucking with this tune update. I do have another fuel adjusting technique which is more suitable for your intake plumbing... I'll use that next time.

[pinstripebob]

Sounds good! I'll give it a go and post a log.

[pinstripebob]

Got the log! Overall the car seems about the same, bucking may have been reduced a bit. I can induce bucking with low RPM off-throttle or low TPS inputs. Shifts seem a bit smoother to me. ECT hits 80C around frame 1800, below are my notes on areas with or without bucking. I did notice a few spots where voltage varied, especially toward the very end of the log.

Steady TPS cruising, no bucking:
Frames 3591-3733
Frames 3931-4096
Frames 4308-4677
Frames 9884-10,105
Frames 10,374-10,617

Steady TPS acceleration:
Frames 2659-2740

Steady TPS cruising, some bucking:
Frames 2877-3034
Frames 3739-3920
Frames 4120-4300
Frames 8348-8387
Frames 8920-9005
Frames 11,987-12,231

Off throttle deceleration, some bucking:
Frames 3242-3485
Frames 5218-5258
Frames 5299-5338
Frames 5380-5415
Frames 5556-5631
Frames 8562-8602
Frames 8703-8821

[pinstripebob]

Post got cut off again. Womp womp.

Off throttle deceleration, some bucking:
Frames 3242-3485
Frames 5218-5258
Frames 5299-5338
Frames 5380-5415
Frames 5556-5631
Frames 8562-8602
Frames 8703-8821 – Bucking stopped for a moment then came back
Frames 10,116-10,231
Frames 12,748-12,784


Off throttle deceleration, no bucking:
Frames 6073-6160
Frames 7765-7863
Frames 9491-9556
Frames 10,627-10,730

Some throttle then no throttle, some bucking occurred:
Frames 13,891-13,938

Notable drops or spikes in voltage:
Frames 837-857 (not up to operating temp, though)
Frames 1093-1104
Frames 8516-8525
Frames 14,545-14,553

Let me know what you think. I'm on country roads, so if there is a specific driving style or scenario you want me to try just say the word. Thanks!

Log:
22608

[statesman]

Don't drive on my Mod4 tune file anymore.... it goes lean in PE. This update won't do anything to help your bucking, it's just to get fueling better.

I tried using my alternate method to adjust fueling and it can't find a solution which maintains a proper MAF curve. I think your aftermarket MAF sensor is junk. How would you feel about replacing the MAF sensor?... I think even a second-hand factory sensor from a junkyard would be better than the sensor you're using now.

I did make an adjustment for your transients... so still do a log with this update.

[pinstripebob]

I don't have an issue changing my MAF sensor. I do have a Delphi part number 25168491 black 85mm MAF I can put in, I have the adapter harness for it as well. We should be able to use it with the MAF curve out of an 2001 Suburban with the 5.3 right?

If I make that hardware change, I have a set of D585 coils I'd like to put on as well. I've been putting off installing both parts, so this may be a good break to put them on. These should need the spark dwell table out of a Yukon with the gen. III 6.0.

In the interim, I'll flash your Mod5 tune and get a log. Is it still helpful when I list portions of the tune with/without bucking?

[statesman]

Yes, listing where it's bucking is still helpful... but make ALL the hardware changes you want to make now, then do a log for me. Use the 2001 Suburban MAF curve, even if it shows lots of trims (as long as it doesn't peg the trims) and use the Yukon spark dwell table for the new coils. Just apply those changes to the Mod5 tune and remember not to drive on the Mod4 tune anymore.

[statesman]

When you post your next log, also post the tune file with all the changes you made.

[pinstripebob]

Got it! I ran back through my log, it goes wicked lean in PE with Mod4! I'll get this flashed before I go for another drive.

I'll post the tune with the log as well. I try to keep a tune history in my comments, with each of your Mods I've transferred your changed tables and written the changes in my history. Helps me keep track of things.

[joecar]

Write long post separately in Nodepad first, then paste to reply.

I've been out of town for a few days, I'm slowly catching up.

[pinstripebob]

Alright I made the changes, did some logging and updated my MAF table. Overall I'm pretty pleased with the results, the car seems to turn on better and drive more smoothly. The MAF table looks like a normal MAF table, too. I Included your Mod5 updates, Statesman, updated the spark dwell table for the D585 coils, and got the MAF table in a pretty good spot. I still have bucking below 1200RPM off throttle, and sometimes at low throttle inputs. I've included the updated tune and the latest log. Below are some roadmap notes for the tune. ECT hits 80C around frame 1290, have a look at IATs for a laugh.

Steady throttle crusing:
Frames 1325-1679
Frames 3321-3707

High throttle acceleration:
Frames 1801-1892

Bucking with throttle input:
Frames 2420-2607
Frames 3834-3867
Frames 4575-4630
Frames 4954-5217
Frames 7586-7686 (pretty bad here)

Bucking during deceleration:
Frames 1917-2139
Frames 2316-2360
Frames 4642-4714
Frames 6738-6769
Frames 10,405-10,465

Let me know what you think, replacing the MAF sensor seemed like a good call, I'm glad I had that Delphi unit sitting around.

Tune:
22633

Log:
22632

[statesman]

I just had a quick look at your log and yeah, your IATs are impressive. I also noticed your engine take a dump towards the end of the log... I'll have to take a closer look at what happened there. I don't have the time right now to run your numbers, but I 'll try to have something for you this weekend.

[pinstripebob]

Yep sounds good! Are you seeing the dump around frame 13,400? It does that periodically, especially with the headlights on. That should have been when I pulled into my driveway and garage. It does that in low speed situations like parking lots occasionally.

[statesman]

Let me know what you think, replacing the MAF sensor seemed like a good call, I'm glad I had that Delphi unit sitting around.

Yeah, this Delphi unit is performing much better. Your fueling already looks reasonable, but I need it a bit closer.

When you flash in this update, I'd like you to also clear your trims.

[pinstripebob]

This last week has been really busy for me, but I flashed your Mod6 and got a good log. I made sure to get up to operating temp, reset the fuel trims, then start the log and start driving. Overall the car is noticeably better under low RPM/low TPS driving, definitely less bucking. It does a better job under "parking lot" conditions, RPM doesn't drop and swing as much.

There was something weird, AFR went lean for a bit. It seemed to go lean after a higher TPS/RPM pull around frame 2,550, very odd. Restarting the engine/widebanad seemed to fix the wideband's readings though.

ECT for the log hits 80C around frame 440. Below are the trouble spots I noticed:

Low TPS bucking:
Frames 1,078-1,126
Frames 1,330-1,368
Frames 2,048-2,080
Frames 3,079-3,321
Frames 4,432-4,525
Frames 4,815-4,875
Frames 4,918-4,973
Frames 5,263-5,395 (pretty bad here)
Frames 5,621-5,717 (bad here as well)
Frames 9,661-9.721
Frames 10,223-10,247

Bucking while decelerating:
Frames 1,729-1,751
Frames 2,180-2,202
Frames 3,480-3,507
Frames 8,332-8,349
Frames 8,373-8,384
Frames 8,456-8,481
Frames 8,863-8,907
Frames 8,951-8,993
Frames 10,254-10,277
Frames 10,966-11,007 (bucking got worse as it dropped RPM)

Let me know what you think. Again, I appreciate the help, thank you!

Log:
22654

[joecar]

...

There was something weird, AFR went lean for a bit. It seemed to go lean after a higher TPS/RPM pull around frame 2,550, very odd. Restarting the engine/widebanad seemed to fix the wideband's readings though.

...

Sorry I was out of town for various reasons.


Is this reproducible...?

[pinstripebob]

Potentially, the WO2 has done this a couple other times a while ago, although I replaced the sensor and calibrated it fairly recently. I can try to make this happen again, during that last log it occurred after entering PE mode.

Sent from Tapatalk mobile

[joecar]

so it's the wideband only...?

[pinstripebob]

Right, only the wideband reading. I have a chance to replicate the conditions of my log tomorrow, I'll try to recreate the problem. It's been an anomaly though, not sure if I'll be able to replicate that lean reading.

Sent from Tapatalk mobile

[statesman]

so it's the wideband only...?

No, it's not just the wideband. Take a look at his last log... it loses the MAF Freq and MAF airflow from frames 2905-2921. Also, the wideband freezes at 16.9AFR for those same frames and it looks like fuel trims freeze for frames 2908-2921. I've also been trying to dial in a chronic rich tip-in and all of a sudden I now have a severe lean tip-in. It's like I'm starting from scratch. There's something really wrong here.

[pinstripebob]

I think that 2905-2921 loss of MAF is when I turned the ignition off (still had it in gear for a moment while moving). The WO2 stays at 16.90:1 from 2904-2959, which correlates to when I turned off the ignition, turned it back on, and a few seconds later the WO2 booted up and started outputting data again. This is also the same period that my voltage goes to zero.

Although that's not to say that something wonky is not going on. I'm wondering if it's related to the electrical charging system? I say that for a few reasons, as follows:
1. The car has 198,000 miles on it. I got it with 105,000 miles in 2012, and replaced the battery in 2013 or 2014 (no date code on the battery). So things are old.
2. When I have the headlights on, the engine will surge a bit when I put it in neutral, or if I'm doing on/off clutch maneuvering in a parking lot or driveway. If I turn the headlights off, surging is almost non-existent.
3. Last week when it was ridiculously cold here (below freezing), I had the ignition on for a few minutes in the morning before I left for work playing with the windshield wipers and it drained the battery enough that it wouldn't start.

Voltage in the logs looks fine to me. In the last log, if you remove the data from the end of the log when I turned the ignition off and the portion of data from 2905-2919 where I turned the ignition off while moving, voltage is 12.5-14.2V for the whole log. The 12.5V drop is at frame 10,893, and everywhere else I'm 13.9V or higher.

Any thoughts on that? Any potential troubleshooting tasks I can perform?

[statesman]

Okay. I didn't know that you turned off the ignition while you were driving. Let's assume for now that changing over to the new MAF sensor has made the fueling go a bit wonky. We're still dialing that in... so it just means that it will take a bit longer now to do that. The logged battery voltage is good... so your charging system is good, but you might want to consider getting a new battery soon. I don't know why your wideband randomly goes crazy and I don't know all that much about wideband troubleshooting, so I can't offer any suggestions there. Maybe joecar will be able to help with that.

With this update I'd like you to do your normal driving log, but right at the end of the log before you shutdown the engine I'd like you to do something extra... I want you to let it idle for a few seconds with headlights off, then blip the throttle and let the idle settle for a few seconds, then put the headlights on and let it idle for a few seconds and then blip the throttle again and then let the idle settle for a few seconds again.

[pinstripebob]

Not a problem, I have a bad habit of not being very clear! I'll try to do better with that. I'll start looking at new batteries, it's probably due for a replacement.

I flashed your tune, let my car warm up a little bit, reset the fuel trims, and took the long drive home. Overall there's a little less bucking, and the engine definitely does a better job not surging when in neutral. I had the headlights and heater on the whole drive home due to weather, but did as you asked once I got in my driveway. Below are my notes on the log:

ECT hits 80C at frame 1303.

Bucking during deceleration:
Frames 1917-1964
Frames 2143-2181
Frames 3685-3719
Frames 4215-4346
Frames 5582-5608
Frames 5891-5950
Frames 5989-6028
Frames 8975-9014
Frames 10305-10369 (stronger bucking here)

Bucking under light throttle:
Frames 2091-2135
Frames 2581-2702
Frames 3012-3091
Frames 4351-4398
Frames 4576-4653 (stronger bucking here)
Frames 10088-10116

Once I got in my driveway, I did the idle/blip for you.
Headlights on, frames 14020-14247
Headlights on, idle, frames 14019-14099
Headlights on, small roll forward, frames 14095-14138 and 14154-14196
Headlights on, quick throttle blip, frames 14200-14240

Headlights off, frames 14285-end of log
Headlights off, idle, frames 14337-14362
Headlights off, small roll forward, frames 14299-14336 and 14364-14401
Headlights off, quick throttle blip, frames 14427-14460

I then pulled in the garage, let it idle with the lights off, and turned it off. Surging in neutral seems to be much better, although if you look at frames 12276-12320 you can see some surging while I battle traffic.

Let me know what you think. Again, thank you very much for the help! If you think of any other specific tests you want me to run, just say the word and I'll give it a shot!

Log:
22661

[statesman]

This must have been a horrible car to drive before I started helping you.

I'm making quite a few adjustments with this tune update. It should be alright, but there's a small chance that some of the changes will clash with other changes and could make the bucking worse in some situations... so if your bucking gets any worse with this update, just say so.

Do your log the same as last time, including the throttle blips at the end of the log. Also, try to replicate the surging while battling traffic.

[pinstripebob]

Alright I'll flash it and get a log, making sure to get some idle surging and throttle blip data. It was definitely not enjoyable when cruising around traffic. I thought I was making some headway, but then I hit a wall and started this thread.

[joecar]

Sorry guys, I've had a lot going on lately... I've been following this thread, but not able to view files while out of town.

statesman, good job :cheers:

[pinstripebob]

Hey Joe, Statesman's been helping out a lot! Stay safe traveling!

I went for a drive home and got another log. I didn't have too many bucking or idleing issues. I did get my other laptop going, so I should be able to log more frequently since it's dedicated to the garage. I did not have my headlights on during the log, except near the end when noted below. Below are my notes on the log, with ECT hitting 80C at frame 1818:

Bucking while crusing:
Frames 2708-2756 (minor bucking)
Frames 4643-4802 (4th gear, very repeatable part of my drive)
Frames 10319-10405 (more undulating bucking)
Frames 10529-10552
Frames 11667-11694

Bucking while accelerating:
Frames 4512-4529
Frames 6867-6880

Bucking while decelerating:
Frames 6201-6219
Frames 6721-6759 (minor bucking)
Frames 8583-8613
Frames 11891-11913

Throttle blip with headlights off: Frames 11993-12022

Throttle blip with headlights on: Frames 12055-12087

The engine speed seems to dip lower and take longer to recover with the headlights on. The log shows the recovery period when speed starts to increase being less sharp and taking a few extra frames, but it seems fairly noticeable in the driver's seat.

Let me know what you think. I haven't noticed any more or less bucking, although it does seem to do a better job returning to idle. I haven't been able to get a good idle surge in traffic.

Log:
22675

[statesman]

statesman, good job :cheers:

Thanks joecar :cheers:

[statesman]

pinstripebob, Ive been away from my computer. I've got a lot to catch up on... will try to get to your log in the next day or two.

[pinstripebob]

Not a problem! I actually tweaked B4515 yesterday and did some driving, that seemed to help reduce idle hunting/surging. I increased it by 50%. Most values in it are lower than my stock tune.

I saw this thread: https://forum.efilive.com/showthread.php?25590-Difference-between-Direct-and-Learned-Idle-Airflow

I've worked with PID controllers in the past. To oversimplify things, P is essentially how quickly you correct your error, I is sort of like a STFT where it gives you a little "memory" of your error, and D helps damp overshoot. The thread above concluded that B4515 was the same as the P value, so increasing it should help the ECU correct idle RPM errors more quickly. I'm a little tempted to zero out the D value table (B4512) just to see how the engine reacts, but that experiment can be saved for another day.

Below is the tune with the modified B4515 table I used. From your Mod8 there aren't any other changes. I've also included my stock tune for reference.

Mod8 with B4515 change:
22682

Stock:
22681

[statesman]

I actually tweaked B4515 yesterday and did some driving, that seemed to help reduce idle hunting/surging. I increased it by 50%. Most values in it are lower than my stock tune.
You might be masking another problem... but if it works for you, then we'll just go with it.


I've worked with PID controllers in the past.
Then you'll know that a high P value can 'appear' to help in some situations, but will cause greater overshoot in other situations. You won't know for sure until you've driven in high ambient temps whether this was a good idea or not.

It's good that you included your latest tune file... we need to be working with the same tune file while I'm making adjustments.

Log the same like you've been doing.

[pinstripebob]

Yeah you make a few really good points. I think I was blinded by optimism.

I flashed your tune, got a log, and overall it seems like things improved. There are still a few trouble issues, but they're fewer and less severe. I logged with the headlights off, but did the throttle blip when I got home with and without headlights on. I didn't have any areas of surging in traffic, although you can see some similar symptoms with the throttle blip. Typing this out, this may be in part to my B4515 change with an excessive P value causing unwanted overshoot.

In the log, the ECT hit 80C at frame 2229. Below are the highlights:

Bucking while crusing:
Frames 2983-3005
Frames 3486-3576
Frames 3750-3865
Frames 4531-4572 (low amplitude)
Frames 5050-5109
Frames 5433-5684 (similar to frames 4643-4802 of post 52 above)
Frames 5906-6530 (pretty long portion of the log)

Bucking while decelerating:
Frames 3043-3058
Frames 4158-4181
Frames 4944-5016
Frames 6536-6569
Frames 7581-7616
Frames 8843-8900
Frames 10458-10492
Frames 10723-10763
Frames 13499-13526

Surging while accelerating:
Frames 5354-5362

Throttle blip without headlights:
Frames 14944-14971
Frames 14972-15019

Throttle blip with headlights:
Frames 15021-15057
Frames 15064-15109

Let me know what your thoughts are. Again I really appreciate the help!

Log:
22685

[statesman]

You've posted your old tune file. Log file names end in dot efi. :hihi:

[pinstripebob]

I had a horrible thought that I posted the wrong file on my drive this morning! :damnit1:

Here ya go, sorry about that!

22686

[statesman]

Typing this out, this may be in part to my B4515 change with an excessive P value causing unwanted overshoot.

Yep, it looks like you've created a bit of overshoot. I'm putting that table back to what it was. Maybe you could hold off making any more random changes until after I've finished helping you.

Your fueling is almost where I want it now. When you do the throttle blips, try to make them the same for headlights off and on. In your last log, the second blip went to about double the TP of the first. I know that it's hard to make two throttle blips exactly the same, but I do need them reasonably close so I can make a good comparison.

Log the same like you've been doing.

[pinstripebob]

I suppose I can hold off making changes. I got a little antsy last week, I've been doing my best not to interfere so I don't throw off what you're testing, this system has enough variables in it without me mucking around.

On that last log, I tried to get a small blip and large blip for headlights off and on. I tried to get four identical blips on this log, the first two without headlights and the last two with headlights. It looks like the 2nd and 3rd blips are pretty close, the 2nd w/o headlights and the 3rd with. Idle is much more stable overall, although lots of turning in a parking garage with headlights on killed the engine (didn't get a log of that, but I can if you'd like). Power steering seems to be tough for the engine/ECU to recover from, other idle situations seem pretty darn good!

Below are my highlights from the log. ECT hit 80C at frame 271, overall things seem to have improved. I floored it in sixth gear and watched my AFR at one point, it was a bit richer than the commanded AFR, 11.76:1 vs 12.53:1 around frame 1420. This was at relatively low RPM for PE, this seemed note worthy to me since fueling seems to be pretty important. There are similar results around frame 1630.

Bucking during deceleration:
Frames 1582-1595
Frames 1760-1863 (low amplitude then higher amplitude)
Frames 1991-2027
Frames 3653-3686
Frames 4180-4220
Frames 4306-4368
Frames 7720-7791

Surging/bucking during cruising:
Frames 2587-2630
Frames 2940-3103
Frames 4554-4577
Frames 5017-5249
Frames 5464-5538
Frames 7802-7915
Frames 8016-8185 (minor then major bucking)

Throttle blip 1, no headlights: Frames 12015-12053
Throttle blip 2, no headlights: Frames 12058-12093
Throttle blip 3, headlights: Frames 12097-12138
Throttle blip 4, headlights: Frames 12143-12180

Let me know what you think, if there are specific tests/logs I can do I'm happy to do them! Thank you again for helping out!

Log:
22692

[statesman]

What spark plugs are you using and what gap are they set at?
What spark wires are you using?... and can you test the resistances?

[statesman]

this system has enough variables in it without me mucking around.

Now you can see why just beating up your cracker table was never going to fix this issue. It's also why most people with long tubes end up running open loop... there's really not much info in the public domain on how to properly tune in closed loop with long tubes (and even if you do know how to tune for them, sometimes you still can't get closed loop perfect).

[statesman]

Idle is much more stable overall, although lots of turning in a parking garage with headlights on killed the engine (didn't get a log of that, but I can if you'd like). Power steering seems to be tough for the engine/ECU to recover from, other idle situations seem pretty darn good!

Just remember that we're logging the data needed for the bucking issue... we're not actually logging all the airflow parameters necessary for dialing in idle. I'm making some adjustments for your idle with very little data, so I am flying almost blind (I'm adjusting your idle more by experience than by hard data). I can make things better, but idle tuning is not what we're doing... so don't expect perfection.

Yeah, the power steering is a drain on the engine... and a cammed engine doesn't have a lot of torque at idle, which is a huge problem. The power steering will always pull the engine rpm down so having sufficient rpm to start with is important and you can get some improvement by messing around with your spark strategy.

[pinstripebob]

I'm using NGK TR55 plugs at the gap they come in. I pulled one out, using the cheap circular gap tools from AutoZone it measured about .062". I need to get a better tool, I used calipers and measured .067" gap. Reading on the Internet what other people use, I should be more in the range of .050"-.055". I can re-gap my plugs, I'll likely get a good set of feeler gages to do so.

Wires are MSD part number 32819. I checked a wire and it measured 26.3 ohms, MSD says the wire is 50 ohms/foot, so that wire measured what it should.

Yeah seeing all the tables you alter is a great learning experience for me, I clearly don't have anywhere close to the experience you have. I do have short tube headers, which should give a bit of a tuning advantage over long tubes.

I'll have to do some reading on idle spark for big cams and power steering. I don't want to pull us off topic since the bucking is our focus right now, I'll do some research and pile up some notes for later.

[statesman]

Time for you to spend a bit of money. Go to an auto store and get a bottle of injector cleaner (google to find a good brand in your part of the world). Pour that into your fuel tank and then drive at least 25miles before you do any logging. If you want to spend even more money, I'd suggest trying TR6 plugs. Whether you keep the TR55 or change to TR6, gap your plugs at .055".

This update will mess things up a bit. I'm lowering your idle spark a bit and I just bumped up the airflow a little bit to compensate... so you'll need to do a RAFPN. You've got a bit of a fueling imbalance in places so no fueling updates this time... I'm hoping the injector cleaner will fix that up. Yeah, your PE at low RPM's is a bit rich... I like to keep things on the safe side so it will be that way a while longer.

I'm making some small changes to your return to idle.... but it seems fairly decent now. Still do the throttle blips when you do your log.

Do everything above before you do your next log.... and post your updated tune file with your next log.

[pinstripebob]

I got some good injector cleaner, had to let my tank get close to empty, and ran that through until I was just about empty again. I also put in TR6 plugs at 0.055" gap. I flashed your tune, did RAFIG, and included that log in this post. That log wanted to increase airflow at 20C and reduce it warmer than that.

I filled up with premium gas and did a log on my way home today. Overall things seem alright, definitely makes sense to keep things a bit richer to stay safe at low RPMs. The log hit 80C at frame 1187, below are the highlights from the drive:

Bucking during deceleration:
Frames 2394-2448
Frames 5182-5253
Frames 7724-7750
Frames 11313-11361
Frames 11428-11471

Bucking during acceleration:
Frames 2550-2559
Frames 12357-12380
Frames 16079-16097
Frames 16807-16868
Frames 18327-18340

Bucking during crusing:
Frames 3270-3547
Frames 5127-5176
Frames 5514-5628
Frames 5687-5792
Frames 6205-6425
Frames 6510-6655

Blip 1, no headlights, frames 20265-20284
Blip 2, no headlights, frames 20285-20308
Blip 3, headlights, frames 20309-20333
Blip 4, headlights, frames 20335-20352

Throttle blip 2 and 3 are pretty similar, not perfect though. Let me know what your thoughts are, or if there's some other test/change I can make. Thanks for the help!

Logs:
22713
22712

Tune:
22711

[statesman]

Okay, this is a bit weird. Normally cammed engines like the TR6 plugs, but your last log doesn't look all that good to me. You're even getting a bit of knock now, which you shouldn't get at all with premium gas. I know it's a bit of work, but I'd like you to gap your old TR55 plugs (if you haven't thrown them out yet) to .055", reinstall them and do another log.

[pinstripebob]

Yep no problem, I kept the TR55s in case it made sense to re-gap them and log some data. I set them to 0.055" and got a good log. Overall, general driving seems to still be improving. Maybe I'm hunting for improvements or being optimistic, but the TR55s seem to reduce bucking over the TR6s on this same tune. Looking at the overall log versus the TR6 log, there's a bit of knock still which is interesting. The big knock events in this log appear to be in the same spot in the main spark table, so there's some consistency.

The log hit 80C at frame 1439, below are my notes on this log.

Bucking during deceleration:
Frames 2202-2239
Frames 2519-2552
Frames 3853-3910
Frames 4101-4143
Frames 5214-5245
Frames 8620-8642

Bucking during crusing:
Frames 2793-2932
Frames 3130-3150
Frames 4394-4537
Frames 6704-6760
Frames 7951-8089
Frames 8531-8600
Frames 9260-9355

Throttle blips:
Blip 1, no headlights, frames 10410-10444
Blip 2, no headlights, frames 10449-10508
Blip 3, headlights/heater, frames 10533-10578
Blip 4, headlights/heater, frames 10584-10628

Blips 2 and 3 are very similar, should be a good comparison.

Let me now what you think, if you want me to try any other tests or make any other changes let me know. Thanks!

Log:
22719

[statesman]

My thoughts on this are that for some reason the TR55's appear to be more suited to your engine than the TR6's for normal street driving. Keep the TR6 plugs... if you ever decide to go racing, you'll definitely need to use them when the engine is working hard all day.

This last log was a little bit shorter than I need... try to get me around 10,000 frames at full operating temperature. Also try to take a long way home which involves a good variety of driving. A log of mostly steady cruising isn't as useful to me as a log which has a good mix of accelerations and decelerations as well as some cruising.

Your return to idle is looking mostly decent, but transient fueling is messing with it in some situations... so we're going to try to eliminate as much of that transient issue as we can.

[voda1]

What version of the tuning software are you using here?

[pinstripebob]

What version of the tuning software are you using here?

I'm using v7.5. I have v8 mostly setup for scanning, but v7.5 seems a little easier since I've been using it longer.

[pinstripebob]

My thoughts on this are that for some reason the TR55's appear to be more suited to your engine than the TR6's for normal street driving. Keep the TR6 plugs... if you ever decide to go racing, you'll definitely need to use them when the engine is working hard all day.

This last log was a little bit shorter than I need... try to get me around 10,000 frames at full operating temperature. Also try to take a long way home which involves a good variety of driving. A log of mostly steady cruising isn't as useful to me as a log which has a good mix of accelerations and decelerations as well as some cruising.

Your return to idle is looking mostly decent, but transient fueling is messing with it in some situations... so we're going to try to eliminate as much of that transient issue as we can.

Not a problem! I've stashed the TR6s in my garage, I'll swap them the next time I go to a track.

I got a log, everything seemed to go pretty well. There were only a couple places where bucking was fairly noticeable. Frames 4837-4857 are probably the worst of the log. I altered my route and got a pretty good mix of cruising and accelerating, hopefully enough decelerating to help out.

I did some throttle blips at the end of the log as well. The first two blips are without headlights, the second two blips are with headlights and the heater on max. Let me know what your thoughts are, or if you need me to make any other changes. Thanks again for the help!

Log:
22724

[pinstripebob]

I remembered something I wanted to point out in case this helps troubleshoot the transient fueling that didn't want to cooperate. After I installed the cam and did some RAFIG logs/tunes, I did some logs and modified my B3702 EOIT table. I ended up lowering it about 0.13 reference pulses. I was having trouble understanding the spreadsheets people made, mainly because I couldn't find the boundary values anywhere.

I've done some re-reading and it makes sense to me now. I ended up changing my timing by 0.10 reference pulses, flashing the tune, and doing a log at operating temp idleing in my garage. I had about 10 different logs for different EOIT values. I plotted my MAP values versus my EOIT value and chose EOIT based on what gave me the lowest MAP reading at idle.

I wanted to point this out in case you wanted to look into changing B3702 at all, or if you thought this might be contributing to some frustration we've had.

[statesman]

I wanted to point this out in case you wanted to look into changing B3702 at all, or if you thought this might be contributing to some frustration we've had.

That was one of the first changes I made, and I told you about it. Back in page 2 of this thread...


I'm making some changes to your fueling... most notably, your injection timing. You were spraying really late... this is unwarranted with your cam.

[statesman]

Not a problem! I've stashed the TR6s in my garage, I'll swap them the next time I go to a track.

I got a log, everything seemed to go pretty well. There were only a couple places where bucking was fairly noticeable. Frames 4837-4857 are probably the worst of the log. I altered my route and got a pretty good mix of cruising and accelerating, hopefully enough decelerating to help out.

I did some throttle blips at the end of the log as well. The first two blips are without headlights, the second two blips are with headlights and the heater on max. Let me know what your thoughts are, or if you need me to make any other changes. Thanks again for the help!

Log:
22724

I think with a couple of more adjustments we should be able to cure most of the bucking. I'll try to get to your log in the next day or two.

[pinstripebob]

Yep I was way late, I had B3702 at 6.32 before you corrected it, sorry about that! Poking around a little more, do we need to lower B3703 a bit based on its description?

[statesman]

Poking around a little more, do we need to lower B3703 a bit based on its description?

No, I don't think so.

[statesman]

I altered my route and got a pretty good mix of cruising and accelerating, hopefully enough decelerating to help out.

Yeah, that was a good log for me to work with. Log the same route again this time if you can.

[pinstripebob]

Got it, same route logged! There weren't any horrible bucking situations, the worst was probably frames 5723-5813 while cruising at low speed/low TPS.

I got a few throttle blips as follows:
No headlights:
Frames 14487-14517
Frames 14516-14578

Headlights/heater:
Frames 14585-14634
Frames 14637-14687
Frames 14690-14742
Frames 14744-14782

With the headlights on, it seems like RPM comes back down nicely, hangs for a moment above idle speed, dips, then comes back up to idle speed. I had a few extra blips with the headlights on trying to get a couple blips that matched headlights off.

I am kind of curious about the times when my commanded AFR is 15.46:1. It looks like when I'm stopped and idling, after a moment the engine commands 15.46:1 for about 4 seconds then goes back to 14.68:1. FUELSYS-A is in OL-Drive. Out of curiosity, what part of the tune is making this happen? CL mode is 8 the whole time I'm stopped, so that isn't changing.

Anyway, attached below is the log. Like I mentioned above, overall it seems to behave pretty darn well under normal driving conditions. Let me know what you think, or if there are any changes/tests you want me to perform. Thank you!

Log:
22742

[statesman]

With the headlights on, it seems like RPM comes back down nicely, hangs for a moment above idle speed, dips, then comes back up to idle speed.

I'm making some more adjustments for this, but like I said previously... without logging all the airflow pids it can be difficult to get a really nice return to idle.


I am kind of curious about the times when my commanded AFR is 15.46:1. It looks like when I'm stopped and idling, after a moment the engine commands 15.46:1 for about 4 seconds then goes back to 14.68:1. FUELSYS-A is in OL-Drive. Out of curiosity, what part of the tune is making this happen? CL mode is 8 the whole time I'm stopped, so that isn't changing.

The PCM does a whole bunch of diagnostic tests while you're driving... this is one of those tests. It will only ever do it at idle. I'm guessing that GM figured that sending you lean at idle was the safest time to do it. Unfortunately, we have no way of disabling this test. It's something you just have to live with.


Like I mentioned above, overall it seems to behave pretty darn well under normal driving conditions.

Yeah, your last log doesn't look all that bad. We'll still do some more changes and see if we can clean it up a bit more.

[pinstripebob]

I'm making some more adjustments for this, but like I said previously... without logging all the airflow pids it can be difficult to get a really nice return to idle.
Yep, I remember you mentioning that. I got a few blips at the end of today's log and the modifications you made without logging all the right PIDs made a big difference for the better.

The PCM does a whole bunch of diagnostic tests while you're driving... this is one of those tests. It will only ever do it at idle. I'm guessing that GM figured that sending you lean at idle was the safest time to do it. Unfortunately, we have no way of disabling this test. It's something you just have to live with.
No worries, I was just curious. I can't tell when the test is performed, although it did catch my eye when I looked through the log. My wife's Cruze performs some test that's probably the same, it's definitely noticeable in her car.

I got a new log with the Mod14 tune, attached at the end of this post. I have an analog gauge on my dash hooked up to my WO2 sensor, I noticed that transient fuel when going from 0 throttle to some throttle seemed to be in very good shape. Very little needle movement, and it snapped back to stoich very quickly.

In some areas the bucking has gone away a bit more, there are a few notable spots as follows:
Frames 233-434
Frames 1689-1780
Frames 9549-9585
Frames 10409-10449

I received a phone call around frame 11,320 and shut the engine off for a minute before turning it back on. I got some throttle blips after waiting 30ish seconds post-restart.

Throttle blip, no headlights:
Frames 11634-11665
Frames 11670-11714

Throttle blip, headlights/heater:
Frames 11752-11785
Frames 11791-11824

Let me know what you think, or if there's a specific test I can do. If you need me to change my driving style or try getting a specific type of driving I can do that as well. Thank you!

Log:
22747

[statesman]

Your return to idle looks decent now but I'm making a small adjustment, so you'll still have to do the throttle blips at the end of the log.

Transients are a bugger to get exactly right. I think your transients now are in better shape overall than they were when we started, so we might just leave them the way they are now.

This update is mainly focused on the bucking issue.

Log like you've been logging.

[joecar]

Good deal :cheers:

[statesman]

Good deal :cheers:

Hey joecar, nice of you to drop in. :cheers:

Yeah, I think this is a good deal for bob... he's getting a decent tune at no cost. :laugh:

[pinstripebob]

Haha yeah I really appreciate the help on this! It's made a huge difference with my car, and me being able to see all the changes you make has really helped me learn! I've been doing a bunch of reading as well, it's freakin' awesome! :cheers:

[pinstripebob]

Flashed the tune, did some driving, and got a log. Overall things feel pretty darn good! The only notable, repeatable bucking during normal driving is low speed, low throttle cruising in 4th gear. A good example in the log to see this is frames 5,221-5,328.

Bucking during deceleration has gotten a lot better. Sometimes it will buck around 1,000-1,100 RPM, but it isn't often. There will normally be a little bucking under 1,000 RPM. It's almost hard to find in the log, frames 10,961-10,984 are an example.

There was some bucking in frames 4,613-4,885 as well, not terrible but it was there.

I did some throttle blips at the end of the log as follows:
Blip 1, no headlights, frames 15,528-15,550
Blip 2, no headlights, frames 15,551-15,589
Blip 3, headlights/heater, frames 15,596-15,622
Blip 4, headlights/heater, frames 15,627-15,670

Let me know what you think, or if there's anything you need me to try. Again I really appreciate the help! Thanks!

Log:
22765

[statesman]

We're almost there.

With this update, I'd like you to do a log like you normally do, then do a calc.VET and update your MAF and VE tables and then do another log. Do the throttle blips at the end of the log like you've been doing.

Post your updated tune file with the two logs.

[pinstripebob]

Awesome! I did as you said, I did a log, updated my MAF and VE tables, and got a second log. I used the PIDs in the CALC.VET tutorial to stay at 24 channels for the VE log, but I think I got some good data and got a decent update on the two tables.

Overall driveability is still improving and seems to be in pretty good shape. There's a little bit of bucking around 25-30mph (40-48kmh) but that's the worst. A couple examples of this are below:

Light throttle bucking:
Frames 4527-4565
Frames 5004-5085

There are some other spots in the log where you can see a bit of surging, but it's very low amplitude and overall the car's driving well. I did some throttle blips at the end of the log as well as follows:

Blip #1, no headlights: Frames 13,104-13,134
Blip #2, no headlights: Frames 13,138-13,171
Blip #3, headlights: Frames 13,213-13,249
Blip #4, headlights: Frames 13,267-13,306
Blip #5, headlights: Frames 13,315-13,344

Let me know what you think, hopefully I didn't do too much damage with those tables! Thanks!

VE log: 22776

Latest log: 22775

[statesman]

That occasional minor surging is going to be difficult to totally cure, but we haven't got much bucking left now which is good. Let's see how we go with this update.

Log like you've been logging.

[pinstripebob]

Yep I wouldn't expect this thing to drive exactly like a factory car. The improvements made so far are very impressive!

I got a log. Again it's driving quite well. There was a bit of inconsistent surging/bucking around frames 4,926-5,070. Other that that the drive was good.

I blipped the throttle at the end of the log as follows:
Blip 1, no headlights: Frames 13,717-13,752
Blip 2, no headlights: Frames 13,754-13,790
Blip 3, headlights: Frames 13,851-13,885
Blip 4, headlights: Frames 13,892-13,936
Blip 5, headlights: Frames 13,948-13,990

I've attached the log below. Let me know what your thoughts are or the next step. The help has been amazing, thank you!

Log:
22782

[statesman]

My thoughts are that we can still make your tune a bit better... so the next step is for you to do another log.

Do some really small throttle blips this time... that's where things are not quite right.

[pinstripebob]

Got it! Things are still improving. There are a few spots where there is some slight bucking, but there weren't any spots that were very high amplitude. Any bucking was fairly subtle, so definitely getting better.

I did a bunch of throttle blips at the end of the log as follows:

No headlights, blips during frames 13,467-13,673
Headlights, blips during frames 13,703-13,988

There wasn't anything that really stuck out to me. Let me know what you think, if there is anything specifically that you need me to do let me know.

Thank you!

Log:
22787

[statesman]

I'm almost happy with that log. This time for part of the log try to back off the throttle earlier and slower than you normally would, so you get some really mild decelerations... and for the rest of the time drive like you normally do.

[pinstripebob]

Sweet, almost there! I got the log, overall the car seems to continue to improve. There were a couple areas of bucking, nothing crazy though. I got lucky and didn't run into much traffic, so I was able to do the mild deceleration you described. Hopefully the data I got is good, if not let me know what I can improve on and I can get another log.

A few spots where I got the mild deceleration captured are as follows:
Frames 2,321-3,307
Frames 3,645-4,022
Frames 5,633-6,014
Frames 7,518-8,156

I did some throttle blips at the end as well as follows:
Headlights off, frames 13,417-13,611
Headlights on, frames 13,616-13,808

For about half the drive, I think starting around frame 8,500, I had my headlights on. It was a bit rainy and got pretty dark during the drive. The last tweaks seemed to make a big difference with the idle staying more stable with the headlights on.

I've attached the log below. If you need me to try anything else let me know. Thanks again for the massive help!

Log:
22791

[statesman]

There were a couple areas of bucking, nothing crazy though.

I can see where it's happening. There's only a little bit of bucking in places now, but we'll still try to get rid of the last of it.


Thanks again for the massive help!

I can tell that you're genuinely grateful... you thank me every time you post.


This time I'd like you to do a throttle position sensor reset and then do a log the same like you did last time.

[pinstripebob]

I did a TPS reset and got a log. There was a little more traffic on my drive, but I managed to get some more mild decelerations like last time in case that helps. A good one is frames 3,100-3,528.

The only bad instance of bucking was during that portion of the log and frames 4,923-4,986. Other than that it's still improving.

I did some throttle blips at the end as well, information as follows:
Headlights off, frames 15,004-15,150
Headlights on, frames 15,198-15,390

It does seem to have a more stable idle overall. And yes I am genuinely grateful for your help!

Let me know if there's anything else I can check or log. I've attached this log below.

Log:
22801

[statesman]

I tried tweaking your transients in the last update and I'm not really happy with the results... so I'm putting them back to what they were.

Most things are where they should be now. I've only got one card left up my sleeve... if this update doesn't fix the bucking, then you're probably going to have to just live with an occasional bit of bucking.

Log the same as you've been logging.

[pinstripebob]

I got another log with this latest tune. Regarding driveability, it has absolutely improved. If I'm holding steady around 40-45kmh with light throttle it will still buck a bit. That sort of behavior is what made me beat up my throttle cracker table in the first place and then start this thread. Frames 4,496-5,205 show some of this bucking, it is mostly very light with a few seconds of the gnarly stuff. That speed has been pretty consistent for bucking, but with this last tune it's definitely better.

I did some more of the low throttle mild deceleration around frames 2,212-2,664. I also did the end-of-log throttle blips as follows:
Headlights off: Frames 13,051-13,183
Headlights on: Frames 13,243-13,419

I wouldn't expect to have stock-like driveability. Your help has been great, and I'm still very appreciative of it! Let me know what your thoughts are. If need me to do anything or try anything, just say the word! I think we're near the end of our road though which is awesome!

Log: 22804

[joecar]

pinstripebob, remind me which intake manifold you have...

[pinstripebob]

Factory LS6 intake with a factory cable driven throttle body. Nothing crazy.

Sent from my Pixel 3 using Tapatalk

[statesman]

Frames 4,496-5,205 show some of this bucking, it is mostly very light with a few seconds of the gnarly stuff. That speed has been pretty consistent for bucking, but with this last tune it's definitely better.

Where that gnarly stuff happens, your fueling is really good and spark is steady. The bucking should be gone... the fact that it's not is telling me that your flywheel is too light for that cam.



If need me to do anything or try anything, just say the word! I think we're near the end of our road though which is awesome!

Yeah, we are near the end of the road. I will get you to try one last update. This update is purely 'experimental'.... it's something I've never tried before, but I remember a few years ago someone claiming that it worked for him... so I figure it's worth a shot.

[pinstripebob]

These last couple weeks have been pretty hectic for me, but I got some good data. I've attached two logs to this post, the first from May 14th is with your updates, the second from May 22nd is after a few of my experiments modifying the 68-140C values you had adjusted. Currently, I have them set to 5.83594, with values 32, 44, and 56C linearly interpolated.

The log from May 14th did not seem to change things much, subjectively. I tried changing these values to stock and up from there, found what seemed to be a range of values where bucking seemed to become less severe and less frequent. I don't think I've found the sweet spot, but I do think I'm in the ballpark. Again that's my butt dyno talking, not my logs' data.

There's a small town I drive through that has a low speed limit, and it normally results in a bit of bucking. Using that as a consistent area for comparing data, I'm inclined to say the later 5.83594 value reduces bucking compared to the earlier 3.50000 value. LTFT average about the same, STFT average a little tighter with the later timing. Of course now that I'm typing this out I wish I had gotten some data within a few percent of 3.5 as well.

These spots are shown in the logs as follows:
May 14th, slow town, frames 4,329-5,192
May 22nd, slow town, frames 4,239-5,140

With more time, I might be able to find the sweet spot, but it's a pretty iterative process that may not warrant many logs' worth of review for you. I imagine I'm probably ready to be cut free, this car does have a lightweight aluminum flywheel and a decent amount of overlap with the cam. For reference, the flywheel is Fidanza part number FID198171 and the cam is Summit part number SUM-8700. It's definitely possible the lighter flywheel is allowing more bucking, and the rest of the drivetrain does seem to have a bit of slop in it which would let all the moving parts clang around rather than damp the movement.

Let me know what you think, your help getting me here has been very helpful and I'm much appreciative of it! Below are the two logs, if you need anything else just say the word!

Logs:
22833
22834

[statesman]

I imagine I'm probably ready to be cut free, this car does have a lightweight aluminum flywheel and a decent amount of overlap with the cam. For reference, the flywheel is Fidanza part number FID198171 and the cam is Summit part number SUM-8700. It's definitely possible the lighter flywheel is allowing more bucking, and the rest of the drivetrain does seem to have a bit of slop in it which would let all the moving parts clang around rather than damp the movement.

Yep, you're ready to be cut free. I've done all that I can... but with that lightweight aluminum flywheel you're always going to get some bucking. You can never completely tune out a physical issue. The last tune was experimental, so go back to the previous tune (which was number 20) and use that as your base tune. I know you've been itching to do your own tuning, so now it's time for you to have some fun. Play around with the tune and you might be able to find a sweet spot. If your changes make things worse, go straight back to that base tune and start over.

Now, to get back to your original question about the throttle cracker. This table is only there to adjust the 'feel' of how much deceleration you get when you let off the gas pedal. When you use lower values in that table, you get a more severe deceleration. Zero that table and the deceleration will feel too harsh for most people. Go too high in that table and you'll get a cruise control effect where you don't decelerate at all. So play with that table to get a level of deceleration which you're happy with... but don't expect that table to do anything for your bucking.

You know which tables I've spent the most amount of effort on.... now I can't stop you playing with those tables, but I would advise you to leave them alone.

Good luck and happy tuning. :cheers:

[pinstripebob]

I've already screwed everything up, I changed pretty much everything and it barely runs!

Just kidding, I've swapped back to the previous and I'll do some tweaking to see if I can't squeeze the last little bit of bucking out of it. I can handle a bit of bucking, but playing with the tune is super addictive.

Good to know on the throttle cracker table! It definitely helps to see what tables really affect how the engine/car behave. I highly doubt I'll touch any of the tables you spent a lot of time on, there's no reason for me to basically undo what's been done and given good results.

Thank you very much for all the help! Cheers! :cheers:

[joecar]

lol on your first sentence :cheers: