Throttle Cracker Tuning Question {B4309}

[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:
GTO March 4 2019 IBC to home.efi

[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:
GTO March 12 2019 RAFIG.efi
GTO March 13 2019 IBC to home.efi

Tune:
Attachment 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:
GTO March 19 2019 IBC to home.efi

[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.