Help understanding throttle cracker

[poolshark021]

I have been on the forum for a while now reading a bunch and trying to take it all in. I bought a flashscan over a year ago but have only been really using it the past few months. I am having an off-idle problem with my car I just can't seem to figure out. Sitting at idle it runs perfect. Once I am driving it gets a little confusing. As I slow down to a red light and push the clutch in, 3 different things might happen:

1. Motor revs up to 1600-1800 rpm and won't come down until throttle cracker is deactivated (right now set at 10mph). Once it deactivates it idles down smoothly.
2. Motor slowly idles down to idle speed just like I want it to
3. Motor stalls out or I have to feather the gas to keep it running until I come to a complete stop.

All three of these things might happen in a 45 minute trip without changing anything. Messing with the throttle cracker table (either small or large changes) doesn't seem to make a difference in the reaction. The only thing that makes a difference is the activate/deactivate speeds. I'm not sure what to even log to look for the problem. I tried logging IAC_TC_M but it didn't seem to show me anything helpful. I will attach a copy of my current OLSD COS5 tune. I have tried using closed loop as well and it doesn't seem to make a difference. Keep in mind I am still new to this so if you see anything out of whack in my tune please let me know. Thanks!

BTW this is a '98 T/A with '02 (0411) pcm. Was an A4 but converted to M6. TR230 cam (230/224 .573/.563 111 lsa) 243 heads milled to 58cc 11.5:1 CR, fast 90/90, pacesetter longtubes with duals

EDIT: Not sure if it matters but my tps reads 0.4% fully closed. I have tried to adjust the throttle screw a little but then it screws up the base idle. Maybe I need to get it to 0.0% then fix the base idle then worry about tc & tf?

[drdarthinvader]

one thing ive found ,have a look at your ve table you have very low numbers from 33 to 44 grams should be around 50s mark..which would make the car difficult to idle. set your throttle cracker tables back to std and use throttle follower for performance in acceleration .if u increase t.f by a% you must increase the decay by the same %

[mr.prick]

What are your logged RAFIG values?

Throttle Follower can also be in the mix:
{B4315} "If both the throttle cracker airflow and the throttle follower airflow are non zero, then the sum of both airflows is added to the idle airflow."

({B4315} + {B4309}) + "idle airflow" ({B4307} :nixweiss:)
I tried logging this "airflow sum" like this:


#Units Low High Fmt Expression
#------------ ------------- ------------- ---- --------------------------------------------------------------
*CLC-00-029
gps 0.0 1.28 0.3 "iff({GM.IAC_TC_DMA.gps}<>0,{GM.IAC_TF_DMA.gps}<>0,{GM.IAC_TC_DMA.gps}+{GM.IAC_TF_DMA.gps})"
lbpm 0.0 0.17 0.3 "iff({GM.IAC_TC_DMA.lbpm}<>0,{GM.IAC_TF_DMA.lbpm}<>0,{GM.IAC_TC_DMA.lbpm}+{GM.IAC_TF_DMA.lbpm})"
# ================================================== ================================================== ===============
#Code PRN SLOT Units System Description
#------------------------- ---- ------------ ---------------- ---------------- ------------------------------------------
CALC.AIRFLOW_SUM FO29 CLC-00-029 "gps,lbpm" Idle "Airflow Sum"

but I'm not sure if it worked right.

TF also has multipliers.
I logged TF last night and found TF had values above 0 when it should not have. :nixweiss:

[poolshark021]

one thing ive found ,have a look at your ve table you have very low numbers from 33 to 44 grams should be around 50s mark..which would make the car difficult to idle. set your throttle cracker tables back to std and use throttle follower for performance in acceleration .if u increase t.f by a% you must increase the decay by the same %I guess I may have screwed up AutoVE at some point (not using filters right or something). I have never manually made changes to the VE table to help acceleration. I have only used BEN factors from my logs to multiply by. Maybe I should just start over with a stock 02 VE table. Also return the TC and TF tables to stock as well...


What are your logged RAFIG values?

Throttle Follower can also be in the mix:
{B4315} "If both the throttle cracker airflow and the throttle follower airflow are non zero, then the sum of both airflows is added to the idle airflow."

({B4315} + {B4309}) + "idle airflow" ({B4307} :nixweiss:)
I tried logging this "airflow sum" like this:


#Units Low High Fmt Expression
#------------ ------------- ------------- ---- --------------------------------------------------------------
*CLC-00-029
gps 0.0 1.28 0.3 "iff({GM.IAC_TC_DMA.gps}<>0,{GM.IAC_TF_DMA.gps}<>0,{GM.IAC_TC_DMA.gps}+{GM.IAC_TF_DMA.gps})"
lbpm 0.0 0.17 0.3 "iff({GM.IAC_TC_DMA.lbpm}<>0,{GM.IAC_TF_DMA.lbpm}<>0,{GM.IAC_TC_DMA.lbpm}+{GM.IAC_TF_DMA.lbpm})"
# ================================================== ================================================== ===============
#Code PRN SLOT Units System Description
#------------------------- ---- ------------ ---------------- ---------------- ------------------------------------------
CALC.AIRFLOW_SUM FO29 CLC-00-029 "gps,lbpm" Idle "Airflow Sum"

but I'm not sure if it worked right.

TF also has multipliers.
I logged TF last night and found TF had values above 0 when it should not have. :nixweiss:

I haven't logged RAFIG in a while because the car will idle just fine sitting still. I do remember that my RAFIG numbers were negative and when I made the changes to my desired airflow table it would cause the car to stall just sitting there so i changed them back. As far as throttle follower goes I have never paid too much attention because all my problems happen when I am off the throttle.

I made a log on the way home today when all these issues happened. Unfortunatly I didn't log any IAC pids because I don't know which ones would be helpful :doh2:. I will post it up later if anyone thinks it might help. In the beginning I come to a stop light and step on the clutch and it revd to 1800 until I slowed to under 10mph. Later I punched it in 3rd gear and then stepped on the clutch and it wanted to stall. A few minutes after that I was doing 80 on the freeway, let off the gas and stepped on the clutch and it stalled out. Then when I was getting off the freeway I stepped on the clutch and it hung at 1800rpm again... a little frustrating...

I was hoping to get this issue tamed at least a little bit before the Woodward Dream Cruise this weekend. I am not against the idea of starting over from scratch but I am worried I wouldn't have the new tune close enough by the weekend. I guess if nothing else I could load this old tune in to cruise around for a while. Overall the car drives great and I am real happy with it. To me this is a minor issue, almost a nuisance more than anything. If you guys want to see the log let me know and I will break down the time frame when each of these problems occured and post it up. At this point I think I am probably better off just starting over...

[SSpdDmon]

I was hoping to get this issue tamed at least a little bit before the Woodward Dream Cruise this weekend. I am not against the idea of starting over from scratch but I am worried I wouldn't have the new tune close enough by the weekend. I guess if nothing else I could load this old tune in to cruise around for a while. Overall the car drives great and I am real happy with it. To me this is a minor issue, almost a nuisance more than anything. If you guys want to see the log let me know and I will break down the time frame when each of these problems occured and post it up. At this point I think I am probably better off just starting over...

I will be a couple hundred feet south of 11 mile on the west side of Woodward this Saturday in Motown Muscle's lot. If you're still having trouble, stop by and ask for me. We can chat then. :)

[poolshark021]

I will be a couple hundred feet south of 11 mile on the west side of Woodward this Saturday in Motown Muscle's lot. If you're still having trouble, stop by and ask for me. We can chat then. :)

I will defintatly take you up on that. I went out to woodward tonight and it was crazy already... I can't wait for saturday!

[poolshark021]

I will be a couple hundred feet south of 11 mile on the west side of Woodward this Saturday in Motown Muscle's lot. If you're still having trouble, stop by and ask for me. We can chat then. :)

Sorry I didn't make it out to see you. I got there a little late and never had enough time to do anything I was planning... anyway thanks for the offer.

[mr.prick]

My TPS% shows 0.4% sometimes too.
Only while parked, on decel it will show 0%. :confused:

[poolshark021]

Am I missing something in the throttle cracker description? As I understand it anytime the vehicle speed is above {B4311} Throttle Cracker Activation Speed the throttle cracker is active and should add the corresponding amount in {B4309} to the idle airflow. How come in my logs there are large amounts of time that the throttle cracker is at 0.00? As long as there aren't any 0.00 cells in my table (which there aren't) the only time TC should read 0 is when it is below the deactivate speed {B4312}, right? I could be doing 30 mph and the TC will read 0. This isn't making sense to me.

BTW I did start over with all stock tables and it didn't work out very well. The car ran worse, wouldn't idle steady at a stop, and the throttle cracker was still acting up causing it to idle high sometimes and to stall at other times. I reloaded my old tune and decided to just tweek on this one some more.

[The Alchemist]

1. Motor revs up to 1600-1800 rpm and won't come down until throttle cracker is deactivated (right now set at 10mph). Once it deactivates it idles down smoothly.
2. Motor slowly idles down to idle speed just like I want it to
3. Motor stalls out or I have to feather the gas to keep it running until I come to a complete stop.

Answer to your issues has little to do with your throttle cracker settings mate as they are set quite low but more to do with your base idle spark table AND your main low/high octane spark table and how they interact with your throttle cracker settings.

B5917 sets the speed at which you transition into base spark in gear, therfore depending on the speed you are at when you clutch it the timing will run either base spark or low octane spark if you are mafless. These spark numbers will differ depending on the zone you are it maybe high maybe low and this greatly affects the resulting idle speed, transition quality etc .
You don't necessarily need to change this setting in your case 6km/hr but more so pay attention to the timing and which of the two maps the ECU is looking at to acheive a good result.
Your third problem with the stalling is plainly obvious looking at your 600 and 400 rpm sites in both tables. Neither of them ramp up the timing as the engine heads towards a stall situation. This together with your 1.3sec "wait" time on the B4505/6 allows the engine to stall before the idle control strategy has time to react. Shorten them to about 0.5 sec or so.
I'll post a map showing what I mean with the spark maps. This will, with some experimentation, eliminate your stalling issues.
So can see that the base spark has an idle area, circled, and this will change from car to car and cam to cam and will need setting for your application, likewise the stall area may need adjusted to suit your car but try these numbers first then fine tune from there. The main spark map also sits fairly high in the low load low rpm areas, these is vital to stop low throttle low rpm surging that often happens with a cammed engine and it also has an anti stall area with the timing ramping up as rpm falls and the load floats towards 0.36 to 0.40. This compliments the base table settings. Once these timing settings are used you can now play with the throttle cracker and fine tune that to suit :)
Hope this helps mate.

Cheers,
Mike

[SOMhaveit]

Yep, the stall with the clutch pedal depressed is corrected precisely as The Alchemist states. Copy his thumbnail spark numbers into your high & low octane spark tables & you will see improvement.

[poolshark021]

I really appreciate your advise... so far I have not messed with the spark tables at all. Funny thing is just last night I was going over logs trying to figure out why my spark advance was bouncing between 20 and 29 degrees while sitting at idle. If I understand you correctly I don't use the base timing table since I have no MAF? It only uses the low octane table at idle? Does it matter if I am using a custom os to restore dual spark maps?

I am going to play with the spark tables before I do anything else next time I take the car out. Hopefully this is the missing piece I am looking for. Too bad it's raining today...

[SOMhaveit]

I believe you do use the base timing tables once the parameters are met even in SD.

[poolshark021]

Well the sun came out and the roads dried up so I made some changes and took the car out. Man what a difference! It still isn't perfect but it's the best that car has ever driven. It has always had good power, I just never knew what to expect when coming to a stop light. It didn't stall on me at all, and for the most part the idle was perfect. A couple times it hung up around 1400-1500 before idling down but that can be fixed pretty quickly. Thanks for the help guys I never would have figured that out on my own. I will keep playing with it but I'm sure I'm on the right path now.

[The Alchemist]

If I understand you correctly I don't use the base timing table since I have no MAF? It only uses the low octane table at idle? Does it matter if I am using a custom os to restore dual spark maps?

Hi mate, pleased I could help :)
To clarify : when in SD or mafless mode the ECU uses the low octane table exclusively during "driving". When at "idle" set by the 1.19tps and 6km/hr the ecu uses only the base timing table in gear (assuming its a manual) even when in neutral.
Only in the autos does it use the base spark in gear when in gear and base spark out of gear when in neutral!
Cheers again,

Mike

[SOMhaveit]

[QUOTE=The Alchemist;102413]If I understand you correctly I don't use the base timing table since I have no MAF? It only uses the low octane table at idle? Does it matter if I am using a custom os to restore dual spark maps?

Hi mate, pleased I could help :)
To clarify : when in SD or mafless mode the ECU uses the low octane table exclusively during "driving". When at "idle" set by the 1.19tps and 6km/hr the ecu uses only the base timing table in gear (assuming its a manual) even when in neutral.Only in the autos does it use the base spark in gear when in gear and base spark out of gear when in neutral!
Cheers again,

You sure about that? The notes in the software indicate the base spark in neutral/park is used when the clutch pedal is depressed. My car fell through the bottom if I pushed the clutch pedal in, but settled in fine when I threw it in neutral and let the clutch pedal out.

[The Alchemist]

Very sure :)
If you open the software and look at the description in base spark in Park/Neutral it does not say "when clutch depressed" it says "when the throttle is closed" OR when in park/neutral ie: an auto trans. Trust me if its a manual you only need to worry about the base spark in gear. If it any doubt simply make them both the same with copy and paste :)

Mike


You sure about that? The notes in the software indicate the base spark in neutral/park is used when the clutch pedal is depressed. My car fell through the bottom if I pushed the clutch pedal in, but settled in fine when I threw it in neutral and let the clutch pedal out.[/QUOTE]

[Highlander]

If you raise b4349 to .0350 or .0390 you will get huge improvements when transitioning to idle and avoid stalls. You will have to scale everything else accordingly but it will HELP A LOT.

[poolshark021]

If you raise b4349 to .0350 or .0390 you will get huge improvements when transitioning to idle and avoid stalls. You will have to scale everything else accordingly but it will HELP A LOT.

I thought that was only for ETC cars?

[SOMhaveit]

Very sure :)
If you open the software and look at the description in base spark in Park/Neutral it does not say "when clutch depressed" it says "when the throttle is closed" OR when in park/neutral ie: an auto trans. Trust me if its a manual you only need to worry about the base spark in gear. If it any doubt simply make them both the same with copy and paste :)

Mike


You sure about that? The notes in the software indicate the base spark in neutral/park is used when the clutch pedal is depressed. My car fell through the bottom if I pushed the clutch pedal in, but settled in fine when I threw it in neutral and let the clutch pedal out.[/QUOTE]

Ok. I had the notes from throttle cracker P/N in my head and made the dangerous leap that in any parameter for P/N the car is considered to be in neutral when the clutch is depressed.

[Highlander]

I thought that was only for ETC cars?
Doh!!!!!!

yeap... my bad.. i am fixated on ETC.

[poolshark021]

Hey guys I'm back with this problem. The stalling is gone completely thanks to the spark tables. Now I just have a hanging idle problem. It doesn't do it all the time, probably 60-70% of the time when I step on the clutch the idle hangs around 1800 until I come to a stop. Then it goes down like normal. The rest of the time it drops to around 1200 until I stop. That is how I want it. I have disabled the throttle cracker tables by turning the enable speed up to 252 mph but the throttle will still hang. Any ideas?

[SSpdDmon]

Hey guys I'm back with this problem. The stalling is gone completely thanks to the spark tables. Now I just have a hanging idle problem. It doesn't do it all the time, probably 60-70% of the time when I step on the clutch the idle hangs around 1800 until I come to a stop. Then it goes down like normal. The rest of the time it drops to around 1200 until I stop. That is how I want it. I have disabled the throttle cracker tables by turning the enable speed up to 252 mph but the throttle will still hang. Any ideas?
Log the airflow pids to see where it's coming from (under System: Idle and Air). Then, you can find where you need to make adjustments in the tune. ;)

[poolshark021]

Log the airflow pids to see where it's coming from (under System: Idle and Air). Then, you can find where you need to make adjustments in the tune. ;)

Funny you say that! I just got done programming them all into my V2. I am going for a ride soon.

[poolshark021]

Well I am having issues seeing my BBL logs and Paul is working on it. I broke the screen on my laptop last week so right now I am kind of dead in the water. Hopefully I will have some results soon.

[poolshark021]

I finally got to do some logging today and I found my IAC steps were all the way down to 0 at base idle. I had noticed it idled a little higher than it should have (100 rpms or so). I checked for a vacuum leak and I didn't find one so I started adjusting the throttle set screw (FAST 90mm TB). It stalled on the first adjustment but after starting up and settling down it was around 40 steps. My test drive went good, no high idle at all. It did stall on me pulling into my driveway but I still had throttle cracker disabled. I'm thinking it should be ok once I enable it again.

What are the chances that throttle screw is vibrating around and moving on me? It doesn't take much effort to turn it by hand and I did notice a slow change in the idle problem. It was very gradual until it got to be annoying and very noticeable. The only other thing I can think of is a vacuum leak and I am very confident that is not the case.

[The Alchemist]

What are the chances that throttle screw is vibrating around and moving on me? It doesn't take much effort to turn it by hand and I did notice a slow change in the idle problem.


Ive had it happen on a couple of T/B upgrades where they slowly Close causing the idle learn to run out of adjustment then you get stalling issues, ingear out of gear issues and such like. The thing is once its all set up nice it only takes 1/4 to 1/2 turn on a large T/B to blow out the idle learn of say 2g/s or what ever you have set and you're history.
Try a drop of thread lock low strength just to stop it from moving.

Mike