E38 runaway idle when rolling

[Cringer]

THAT helped alot. You think it was too much idle timing? Everything feels pretty normal now, no more running away in gear. Thanks for all your help Cringer, you da man.

Whew glad to hear it! I dropped idle timing to 18* as a matter of best practice. But the real fix was dropping idle follower torque. You can experiment with that a little more as needed to fine tune it.

[CptFalcon]

Cool I will mess around with it some and see how it reacts.

[blindsquirrel]

Were there solid, evidence-based reasons for changing all this stuff?
screenshot.14-11-2024 20.08.14.png

[Cringer]

Were there solid, evidence-based reasons for changing all this stuff?
screenshot.14-11-2024 20.08.14.png

Have to ask GM for that evidence. Using LS9 from Corvette ZR1 works great with aftermarket cams. Even better than LSA settings.

[blindsquirrel]

No, I mean all those changes were in the first file posted. Why? If it was you who'd changed them from stock that'd be one thing, but somebody new who shows up with idle problems with all those tables having been finger-fucked?

[Alvin]

Whew glad to hear it! I dropped idle timing to 18* as a matter of best practice. But the real fix was dropping idle follower torque. You can experiment with that a little more as needed to fine tune it.

The idle coast down running up to 34d off idle is likely the cause of this. I'd be interested in what it does put all back except that.

[Cringer]

No, I mean all those changes were in the first file posted. Why? If it was you who'd changed them from stock that'd be one thing, but somebody new who shows up with idle problems with all those tables having been finger-fucked?

Someone already did the correct thing and changed them from stock to LS9 settings. I verified this. The only changes I made the P/I controller was smoothing out the over and under mult tables 12152/12153.

[Cringer]

The idle coast down running up to 34d off idle is likely the cause of this. I'd be interested in what it does put all back except that.

Would be an interesting test. Post the file and see if OP will test.

[CptFalcon]

I'm willing to give it a shot.

[CptFalcon]

Quick update mostly for documentation purposes. I continued struggling with this, every change seemed to make it slightly better or much worse. I got fed up and copied in a bone stock tune and just entered in the essentials to make it run like injector data, displacement, VVE, MAF etc, and it stopped driving off, then copied in Hi and Lo spark tables, still good, then idle spark, still good. You get the picture. Then I copied in the ZR1 idle adaptives and boom, there it was. The truck went from a nice relaxed idle to feeling very high strung and began running away after the 1.2 mph mark. I didnt think adaptive idle would effect what happens OUTSIDE of adaptive idle but in this case it did...dramatically. Its a shame because the ZR1 stuff handled the cam nicely, but it didnt play nice with this setup. Im not sure which table was causing this or how to break it down but its back to stock for now and working fine.

[edcmat-l1]

Quick update mostly for documentation purposes. I continued struggling with this, every change seemed to make it slightly better or much worse. I got fed up and copied in a bone stock tune and just entered in the essentials to make it run like injector data, displacement, VVE, MAF etc, and it stopped driving off, then copied in Hi and Lo spark tables, still good, then idle spark, still good. You get the picture. Then I copied in the ZR1 idle adaptives and boom, there it was. The truck went from a nice relaxed idle to feeling very high strung and began running away after the 1.2 mph mark. I didnt think adaptive idle would effect what happens OUTSIDE of adaptive idle but in this case it did...dramatically. Its a shame because the ZR1 stuff handled the cam nicely, but it didnt play nice with this setup. Im not sure which table was causing this or how to break it down but its back to stock for now and working fine.

I preach it all the time on here. Don't go screwing with idle adaptives. The vast majority of the time it makes things worse not better.

[Cringer]

The idle adaptives, just like everything else, are tied into everything else. The over and under spark adaptives, Min Final Air, Min Final Spark, Idle Spark, Coast Idle Spark, and Idle Follower Torque. So when when you started moving everything back to stock and then applied the only the adaptives...I guess I am not surprised. With the results.

I do agree that starting from a stock tune and slowly working up is the best course of action. I also agree that messing with/trying to tune the already created OEM adaptives is a bad move. I am glad you are finding luck and learning on the way. Like a lot of this stuff, the learning curve tends to go from hard, to easy, then back to hard as you learn more...then a long process of getting easy again.

[CptFalcon]

The idle adaptives, just like everything else, are tied into everything else. The over and under spark adaptives, Min Final Air, Min Final Spark, Idle Spark, Coast Idle Spark, and Idle Follower Torque. So when when you started moving everything back to stock and then applied the only the adaptives...I guess I am not surprised. With the results.

I do agree that starting from a stock tune and slowly working up is the best course of action. I also agree that messing with/trying to tune the already created OEM adaptives is a bad move. I am glad you are finding luck and learning on the way. Like a lot of this stuff, the learning curve tends to go from hard, to easy, then back to hard as you learn more...then a long process of getting easy again.

Yeah it just shows you can't just pick out a piece of another engines tune, plug it into another tune and expect it to work properly because like you said so many other parameters have been tailored around each other and depend on one another to function. Especially taking something from a car that has a roots blower and manual trans and putting it in a truck with a tight converter. The requirements are just so different.

[Alvin]

I've never and I do not know of any other professional tuners that copy any idle settings out of another car. Well other than hardware stuff. Like injectors, map sensor data, etc.

[Cringer]

I've never and I do not know of any other professional tuners that copy any idle settings out of another car. Well other than hardware stuff. Like injectors, map sensor data, etc.

Firstly:
Not trying to start a fight or anything, so don't read anything more into my comments than needed.

Secondly:
Are you saying you NEVER touch (a) the throttle P/I controller and (b) the over/under spark tables? You leave both of these areas bone stock?

Thirdly:
The term "professional tuner" is pretty broad. There are a lot of people that accept money for tunes and that technically makes them a professional, but obviously does not guarantee a top tier tune. In my experience, most full time professional tuners working out of a shop don't even touch VVE. As for me personally, I have used two local full time professional tuners to tune my car. I was not impressed with the results and my hand was forced to sort it out on my own. I think if you look at this forum, half the people here are noobs that don't know anything about tuning and the other half are seeking help from a botched tune.

In my opinion what professional tuners do and do not do should not be used as the gold standard. Yes professionals, such as yourself, have a ton of knowledge and experience to draw on, which is invaluable. I wish I had that to draw on myself! We are all enriched to have you sharing your knowledge with us. But since I don't have years of tuning experience on every known car and hardware combination, my modus operandi is to challenge all assumptions and question everything. Hence my motto, "A standard approach will give you standard results." Sure, I love being right. But I thrive when I am wrong and learn from it — as it is the only way to get better.

[Alvin]

No I never copy out of another stock tune idle settings nor spark over under tables out of other cars.. You are putting words in my mouth saying I "leave them bone stock"

The only thing I'll copy out of another stock tune is for injector were car B has the injectors I'm using in car A. Or map sensor settings. I will not copy VVE out of another stock car or anything spark related.

I mean what made you chose a ZR1 to copy from anyway? Not much at all in common between these two. I'm trying to understand. It's not like a low production car would have things as fully flushed out as a more common platform anyway.


And you are right.. there are a lot of shops who copy /paste HPTuners supported vehicle list into their own "we offer tuning for" Lots and lots of rough work out there. There are a lot of others who have tuned very few cars and because of that don't have a hammered out strategy that works every time.



----- If you guys look at my original post in this thread you'll see I pointed out idle timing goes VERY high at a roll. This will cause idle to run away. I'll bet just fixing that would have fixed the whole issue.

[CptFalcon]

----- If you guys look at my original post in this thread you'll see I pointed out idle timing goes VERY high at a roll. This will cause idle to run away. I'll bet just fixing that would have fixed the whole issue.

Sorry I forgot to post that revision I did reduce timing in that area right after you posted that and it didnt help at all. Not sure if this is how you would have done it but it made sense to me and my non tuner brain lol

Screenshot 2024-12-02 114059.png

[Cringer]

No I never copy out of another stock tune idle settings nor spark over under tables out of other cars.. You are putting words in my mouth saying I "leave them bone stock"

The only thing I'll copy out of another stock tune is for injector were car B has the injectors I'm using in car A. Or map sensor settings. I will not copy VVE out of another stock car or anything spark related.

I mean what made you chose a ZR1 to copy from anyway? Not much at all in common between these two. I'm trying to understand. It's not like a low production car would have things as fully flushed out as a more common platform anyway.


And you are right.. there are a lot of shops who copy /paste HPTuners supported vehicle list into their own "we offer tuning for" Lots and lots of rough work out there. There are a lot of others who have tuned very few cars and because of that don't have a hammered out strategy that works every time.



----- If you guys look at my original post in this thread you'll see I pointed out idle timing goes VERY high at a roll. This will cause idle to run away. I'll bet just fixing that would have fixed the whole issue.

I am not putting words in your mouth intentionally. I am just asking clarifying questions.
For example you seem to indicate that you do not leave them stock nor do you copy from another vehicle...so it sounds like you are saying that you hand modify the OEM adaptives?

OEM LS9 adaptives are for a big cam (by OEM standards) 211* / 230* and .562" / .562". Thus it seems like a much better starting point than any other adaptives for a vehicle that has an aftermarket cam.

And either way, the adaptives are just part of a larger idle tuning strategy. I don't think it is the silver bullet to solve the issue.

[Alvin]

Sorry I forgot to post that revision I did reduce timing in that area right after you posted that and it didnt help at all. Not sure if this is how you would have done it but it made sense to me and my non tuner brain lol

Screenshot 2024-12-02 114059.png

That is far too high still. But you may have other things compounding. Watch your idle timing.. then compare it to where you were seeing this runaway idle at a roll.. You'll see the difference.

[Alvin]

I am not putting words in your mouth intentionally. I am just asking clarifying questions.
For example you seem to indicate that you do not leave them stock nor do you copy from another vehicle...so it sounds like you are saying that you hand modify the OEM adaptives?

OEM LS9 adaptives are for a big cam (by OEM standards) 211* / 230* and .562" / .562". Thus it seems like a much better starting point than any other adaptives for a vehicle that has an aftermarket cam.

And either way, the adaptives are just part of a larger idle tuning strategy. I don't think it is the silver bullet to solve the issue.

The actual idle/throttlebody PID stuff RARELY gets touch in any of the things I do.. Very rarely. Yet on here they seem to be part of the first few steps in tuning.

I honestly doubt many could explain how a PID controller works in normal conversation. If you ever looked into any industrial PID tuning process.. it's not completely straight forward. There are a few approaches you can take with math but most of it is at least finalized just by tweaking and observing results. And the math is pretty high level stuff. (diff eq or any high level class on vibrations) Yet I never see anyone on here mention.. my idle error is high for too long, i'll go adjust my I terms. Or I'm getting a slow long term oscillation.. it must be I. There doesn't seem to be a D.. at least defined by HPTuners. It's just a multiplied it by X.. or i copied it out of this OEM car.

So considering the understanding of PID or PI are outside most peoples skill set.. and also considering AIRflow/throttlebody is absolutely the slowest way to control idle. It doesn't make sense for people to go to this.. at the very least until all the basic fundamentals of the tune are ironed out. And that is my, and so many other's point.. Get the basics fully flushed out.. and little issues like this will resolve themselves automatically.

idle spark tuning for me is all done by hand and I consider it a first step when tuning.


Just in case you think I'm not tuning these because I don't understand them.
I've got a degree in Mechanical Engineering. I was one class short in math for a math minor. I barely passed English. lol
I've done servo controllers, temp controllers, and I had a drone tracking business that used some pretty cool PID control. One of the temp controllers I did was for distilling. Which was sorta neat. I could command a temp to precisely pull off a higher quality of whatever I was looking for. Also a bit challenging cause as the volume changed the amount of heat needed changed radically. Along with phase change heat.