Looking for some help/advice on E38 Idle

[edcmat-l1]

Ok great, so now looking at my logs I can see the idle is likely what is causing the swing in spark correction causing my idle oscillation's.

It is the over active throttle blade that is causing most of the RPM oscillations. I blew up both line graphs so you can see it better.

Throttle blade oscillation.jpg

You have to undo your prop table settings, make your spark tables a little more aggressive, and get the VVE dialed in so you're not idling in a ditch.

You need to lessen the throttle movement so your spark isn't chasing it around. Not sure how many different ways I can say it.

[hjtrbo]

You don't need a wideband to get the majority of your tuning done, and most importantly, all of the start-up and idle tuning.

Your VVE needs to look like it makes sense. You can't idle in a steep valley where every time you move out of that valley you move into a much higher cell whether you go up or down both in RPM and/or MAP.

You need to put the majority of the calibration back to stock and concentrate on getting your most basic tables straight. By doing so you'll need to change far less other random tables like idle PIDs.

That's the best advice you'll ever get. kiss

[edcmat-l1]

1) how come the idle oscillates while its warming up and once it warms up the idle is rock solid?

There's so much wrong in the calibration there's no single answer for this. It is a combination of several things.

2) I have only set the idle on the VVE table. It initially needed to be cut back almost 40% in some areas so that's why the valleys. Yes I know its a bit of a mess but what would be the
easiest way to straighten things out "Just" to get it idling better?

There's no easy way to answer this other than it needs to have a certain shape. It needs to be lower in the lower RPM columns and lower in the lower MAP rows.

I would prefer to stay a MAF and Speed density table combined as opposed to straight Speed density.

Yes I know speed density may be simpler but I really want to learn how to tune them both.

It's not that SD is easier, it's that it runs better in these cars C6 Z06s. The main reason is the MAF is right in front of the throttle body and with a lopey cam the maf responds to the reversion. You can watch it happen in the scanner. The maf flickers or twitches and it adds to the trailer hitch effect. In speed density it completely eliminates that.

[Allen Vos]

It is the over active throttle blade that is causing most of the RPM oscillations. I blew up both line graphs so you can see it better.

Throttle blade oscillation.jpg

You have to undo your prop table settings, make your spark tables a little more aggressive, and get the VVE dialed in so you're not idling in a ditch.

You need to lessen the throttle movement so your spark isn't chasing it around. Not sure how many different ways I can say it.

I read you loud and clear. I was just trying to understand why it was doing what it was doing.

Initially I had thought the Oscillations in VVE were because of the oscillation's in the Spark which changed RPM which changed the MAP values causing it to run on a different spot in the VVE table.

But its looking like based on what you are saying its the VVE table causing the swings in RPM along with the spark tables.

I ask all these questions because I am trying to understand all this and make sense of it.


What I was trying to ask you is , what is the best way to smooth the VVE table?

I have already gone in and made changes to bring the VVE numbers down as they were 40 % higher.

So am I best to go in and just smooth things out manually around the idle numbers to fix this?

How would you go about fixing the VVE table?

[edcmat-l1]

How would you go about fixing the VVE table?

Interpolate and smoothing.

This is your VVE with a few button clicks.

VVE.jpg

That's all I changed. Good luck with it. Like I said many times I'd undo a bunch of what you've done and just concentrate on tuning it strictly in speed density.

TSP Stage 2 Camshaft with CTS idle proportional and intergral table with MAF plus VVE changed_E.hpt

[smokeshow]

I bet that VE fixes almost all of the issue by itself.

[Allen Vos]

Interpolate and smoothing.

This is your VVE with a few button clicks.

VVE.jpg

That's all I changed. Good luck with it. Like I said many times I'd undo a bunch of what you've done and just concentrate on tuning it strictly in speed density.

TSP Stage 2 Camshaft with CTS idle proportional and intergral table with MAF plus VVE changed_E.hpt

Thank you for being patient with me. I was used to tuning on an older system called Mega Squirt which was a very very simple setup on speed density.

I am a slow learner when it comes to this stuff as I try to be very through and try to understand why things get changed the way they do.

But I do understand things completely once they sink in. lol



Thank you kindly for your help, I will try this out later next week when I get back to the car and report back.

[ns158sl]

I wish there was more of a half ass explanation on how to tackle Prop vs Integral for idle swings. I know people say stock are fine. Well there are quite a difference between say a 5.3 and an ls7 lol. So far softening Prop as little bit seemed to help, but then I added integral to quicken up the idle oscillation. Seems better overall but it still has a surging. I will be curious what the OP will post once his VE is dialed in.

[edcmat-l1]

I wish there was more of a half ass explanation on how to tackle Prop vs Integral for idle swings. I know people say stock are fine. Well there are quite a difference between say a 5.3 and an ls7 lol. So far softening Prop as little bit seemed to help, but then I added integral to quicken up the idle oscillation. Seems better overall but it still has a surging. I will be curious what the OP will post once his VE is dialed in.

It all depends on when it surges as to what needs changed to eliminate or lessen it. Like I've said here ad nauseum I very rarely touch the PIDs. I want the least amount of over/under correction in the blade. I definitely don't want to increase the movement.

[Cringer]

I wish there was more of a half ass explanation on how to tackle Prop vs Integral for idle swings. I know people say stock are fine. Well there are quite a difference between say a 5.3 and an ls7 lol. So far softening Prop as little bit seemed to help, but then I added integral to quicken up the idle oscillation. Seems better overall but it still has a surging. I will be curious what the OP will post once his VE is dialed in.

Jerry Seinfeld had a joke about people going into those big box stores and buying loads of toilet paper (this was well before COVID was a thing) and observed that these people are tackling the problem from the wrong end. This is the same thing in regards to attempting to fix idle issues using the idle air PIDs.

I assert that about 90% of throttle control SHOULD BE done with proper min final airflow and base idle advance.
And about 9% of idle control should be the over/under spark correction.
The remaining 1% will be done with the idle air PID controls, and this should be the lightest touch.

<< I am making these percentages up, they are not scientific, but just trying to demonstrate the relative importance >>

This means that if you are attempting to fix idle issues with the idle air PIDs, you are tackling idle from the wrong end. You in fact never want the ECM to have to resort to using the idle air PIDs if at all possible. They are a last ditch effort to control idle RPM.

[edcmat-l1]

You in fact never want the ECM to have to resort to using the idle air PIDs if at all possible. They are a last ditch effort to control idle RPM since air.

This right here.

[Alvin]

I wish there was more of a half ass explanation on how to tackle Prop vs Integral for idle swings. I know people say stock are fine. Well there are quite a difference between say a 5.3 and an ls7 lol. So far softening Prop as little bit seemed to help, but then I added integral to quicken up the idle oscillation. Seems better overall but it still has a surging. I will be curious what the OP will post once his VE is dialed in.

Even in that situation the stock stuff is fine.

Before getting too deep into any idle tuning the fueling needs to be as close as possible. If its got a decent cam in it, it should be done in SD first. It's not that SD is easier. I'd argue it's harder. It's that a MAF sensor reads cam reversion so it sorta double dips reading airflow.

I agree with whoever said something along the lines.. "best to go back to mostly stock and only fix the most basic tables first" Everything else will likely fall right in line just by doing that.

[ns158sl]

Virtual torque also affects idle. Obviously without an engine dyno a guy is pretty much adjusting it blindly. I still think a chassis dyno with an arbitrary multiplier for parasitic loads and drivetrain loss would be better than leaving the VTT stock.

[smokeshow]

Guess it'll just remain a mystery why idle airflow control exists at all

[ns158sl]

Guess it'll just remain a mystery why idle airflow control exists at all

You wouldn't understand, just crack the throttle blade open further, duh. Lmao.

I am guilty, along with others, of what Alvin keeps iterating of getting fueling spot on before going about turning all the knobs.

[GHuggins]

Guess I go against the grain on this. Yes airflow and fueling need to be dialed in. There's no discussion there, but I also believe in adjusting the other players as well. Manuals for example have a lot of "clutching" gains in the proportional table. Even very light throttle driving can be affected by it. The integral table is actually what controls idle spark corrections, so I don't understand how you can say you want as little correction as possible while relying on spark? They actually both control spark whereas proportional primarily controls throttle or your immediate "big" corrections.

Don't know, I just prefer to optimize all that I have. I agree at a "rest with no loads much" I like to have very little plate movement, but there's still other aspects to idle than just "at rest with no loads".

[smokeshow]

I agree at a "rest with no loads much" I like to have very little plate movement, but there's still other aspects to idle than just "at rest with no loads".

[edcmat-l1]

The gist of the thread seemed to be at rest idle stability. That's what all of my comments have been based on. Further, if we're talking about anything other than at rest idle, we're not really talking about idle stability are we? We're talking about off-idle, return to idle, etc. If we're expanding our conversation into these other off topic, off idle subjects, I still very rarely use PIDs. There are other tables for those situations.

[smokeshow]

The idea I was trying to get across was compensation for external loads. They're what we call 'idle cramping' scenarios in Detroit. From an otherwise steady idle, load up the engine with garage shifts, AC, cranking the wheel, loading down the alternator with power windows rolling up, etc. Enough load and you'll run out of spark to make a correction...that's one place where the idle airflow control really comes in handy.

[edcmat-l1]

All of those scenarios have individual tables to help in each individual situation, without having to touch the PIDs. Trans shit transition tables, AC load torque tables, etc. I feel it's more accurate to address each scenario with the corresponding table rather than affecting the overall over/under actuation of the blade.