Looking for some help/advice on E38 Idle

[Allen Vos]

Hello All

I have been messing with the idle settings for a little bit on my 09 LS3 E38 PCM with a stage 2 TSP cam and long tube headers.

For now I am using the narrow bands to dial things in and will be adding a wideband in the spring to do some PE tuning and dial everything else in a bit nicer.

The cam specs are as follows TSP Stage 2 Cam 229/244 .629"/615? 112 LSA, 109 ICL

I have dialed in EOIT and SOIT to match the Cam. EVC = 394^ and SOIT at idle is 389^ with the Injection boundary set to 470^

I have the car starting up cold with some rpm oscillating until 80 degrees Celsius then it smooths out considerably.

I have a few things I feel I can or need to change but want to run it by you guys first for clarification.

I will include the tune and my latest log with a cold start until warm up.


I have changed the following from stock.

1) Spark advance/idle adaptive spark over and under speed tables. > cut them all in half or multiplied by (.5)

2) base spark has been set to 16 degrees throughout the entire table

3) I have used the method in this guide to figure out a base idle air flow of 10 g/s and 16^ base timing and idling at 800rpm for a very smooth idle

https://forum.hptuners.com/showthrea...e-tuning-guide

4) idle/rpm - adaptive idle overspeed error correction table was cut in half or multiplied by (.5)
The one thing I noticed is my 2009 vette idle adaptive over speed correction table values were lower at 20 and 32 degrees were cut in half as compared to the rest of the
values. However I have seen recommendations to use integral and proportional tables from a 2010 CTS, 2014 Camaro SS or a 2013 A6 Vette. all of these vehicles have a
much more even error correction table for the over correction table.



So after extensive reading I think I have a handle on things. There are many guys who just disable Proportional Air flow and just stick to integral air flow with more aggressive cams or just raise the error correction on the Proportional Air table. I would like to do things correctly and properly so I'm guessing sticking to the proportional air flow table is a better way to go, but I am not sure?

I did notice the proportional table does not do a whole lot in my case except for cold start and if I rev the engine up a bit. If it is only idling and warmed up it seems like its using the integral air flow table. I have attached my log and this will show both these tables.

I am planning on dropping the base air flow table to 10 g/s at operating temp to see if that will improve things but I also noticed my start up airflow table is messed up around 10-20 degrees ECT so I really need to clean that up as I believe its affecting the idle on a cold start.

My idle oscillates a fair bit until the engine warms up to 80 degrees then smooths out. I can see the overspeed/under speed correction tables are causing an unstable idle and wondering if I should reduce/relax them a bit more.

One thing I read is with the camshaft to let it idle the way it wants to, as in ,it will hunt up and down slightly and to just let it do that and loosen the error correction a bit.

Just looking for some pointers here, hopefully someone can chyme in.

It would be greatly appreciated.







Attachment 141936

Attachment 141937

[edcmat-l1]

I've tuned several hundred LS3 Corvettes, Camaros, LS7 Vettes, some with huge camshafts. I don't do 1/2 that crap and they idle and return to idle just fine. Even light flywheel road race cars. LS7s that make nearly 600 RWHP on pump gas. You're changing stuff that for the most part doesn't need to be or shouldn't be changed.

[Allen Vos]

I've tuned several hundred LS3 Corvettes, Camaros, LS7 Vettes, some with huge camshafts. I don't do 1/2 that crap and they idle and return to idle just fine. Even light flywheel road race cars. LS7s that make nearly 600 RWHP on pump gas. You're changing stuff that for the most part doesn't need to be or shouldn't be changed.

So are you suggesting that the proportional and integral air flow plus the idle adaptive overspeed and under speed tables never need to be touched when installing a more aggressive camshaft than stock and expecting it to idle perfectly ?

I'm confused as to your response as the majority of these guides/threads all talk about modifying the proportional and integral airflow tables along with the error tables plus loosening the overspeed and under speed spark tables to avoid oscillation's in RPM for a steady idle.

So being as this is a forum where people come to get help and more importantly learn how do to things correctly, why don't you share you methods?

Maybe you can offer some advice on how I should be setting my tune up to idle perfectly, which in turn would help others out who have similar issues down the road?

[edcmat-l1]

So are you suggesting that the proportional and integral air flow plus the idle adaptive overspeed and under speed tables never need to be touched when installing a more aggressive camshaft than stock and expecting it to idle perfectly ?

I'm confused as to your response as the majority of these guides/threads all talk about modifying the proportional and integral airflow tables along with the error tables plus loosening the overspeed and under speed spark tables to avoid oscillation's in RPM for a steady idle.

So being as this is a forum where people come to get help and more importantly learn how do to things correctly, why don't you share you methods?

Maybe you can offer some advice on how I should be setting my tune up to idle perfectly, which in turn would help others out who have similar issues down the road?

When you loosen the over/under spark tables, you increase oscillation, not decrease. When you modify you prop and integral tables, you're changing the blade response time which in most cases increases oscillation, not decreases.

Some vehicles need the over/under tables loosened up some, they're too aggressive. But you get to a point where if you don't have enough spark control it tries to use the blade and then it really gets out of hand. The more you reduce the spark control the more it wants or needs to use the blade to control idle. You don't want that. You want the blade to move as little as possible to maintain idle.

Modifying your prop and integral tables is not needed in most all cases. What ends up happening is you end up making the blade over responsive and that exacerbates the problem.

Setting up your BRAF, your start up airflow and your spark over/under tables is typically as much as you need to do. GM's settings for prop and integral work just fine with pretty much any throttle body. I recommend leaving them alone you end up doing more harm than good.

[smokeshow]

That's interesting.. I always tend to do almost the exact opposite. GM cal procedures actually mandate that the engine meet idle requirements with immediate/spark path disabled - it's really meant to be used as a last resort for disturbance rejection using idle reserve. It makes sense that the goal should be to make idle corrections without dipping into the torque reserve, ie spark correction. Bigger cams make this an impossibility, but idle airflow feedback cal is still very useful.

[edcmat-l1]

That makes no sense to me. You can't control idle speed and stability near as accurately using the throttle blade. You just can't. It can't react fast enough and in small enough increments.

[smokeshow]

No, not with an aftermarket camshaft. Active misfires change things a bit lol. But those airflow tables are still useful for the same reasons they are on stock applications. Idle is always smoother after they've been addressed.

[edcmat-l1]

I disagree. I want the blade to do less of the work for idle control, not more. I want enough spark control to keep the blade from over correcting, but low enough spark control to keep the "rump rump rump" idle to a minimum.

[Allen Vos]

When you loosen the over/under spark tables, you increase oscillation, not decrease. When you modify you prop and integral tables, you're changing the blade response time which in most cases increases oscillation, not decreases.

Some vehicles need the over/under tables loosened up some, they're too aggressive. But you get to a point where if you don't have enough spark control it tries to use the blade and then it really gets out of hand. The more you reduce the spark control the more it wants or needs to use the blade to control idle. You don't want that. You want the blade to move as little as possible to maintain idle.

Modifying your prop and integral tables is not needed in most all cases. What ends up happening is you end up making the blade over responsive and that exacerbates the problem.

Setting up your BRAF, your start up airflow and your spark over/under tables is typically as much as you need to do. GM's settings for prop and integral work just fine with pretty much any throttle body. I recommend leaving them alone you end up doing more harm than good.

Sorry I should have clarified that loosening up the spark tables in my eyes meant smaller numbers on the over and under speed spark correction tables so it does not oscillate or swing too much. I do understand a lumpy cam so to speak is going to idle up and down on its own naturally so the settings need to be relaxed to allow the cam to idle the way it needs too.

It would appear you have a different opinion on the proportional and integral tables and I do understand there are different ways to do the same thing, however the masses seem to be using integral, proportional and over and under speed all together to tune for a stable idle.

Here is the thing. I'm smart enough to figure things out as I play with them but I don't know enough yet to go off the beaten path and figure things out my own way yet so its hard for me to follow someone that does things a bit differently than others.

So I will just ask you. If you take a look at my tune and logs knowing I would like to stabilize the idle, what specifically would you do if you were me?

I have set min air flow and have it very close and need to clean up the startup air flow a little bit.

I have also cut the overspeed and under speed spark tables in half and noticed a huge difference in the idle. It does not oscillate near as much as it first did when I fired it up for the first time. So I know I am going in the right direction.

[Allen Vos]

That makes no sense to me. You can't control idle speed and stability near as accurately using the throttle blade. You just can't. It can't react fast enough and in small enough increments.

Correct me if I'm wrong here, but yes spark advance and retard is the better way to control your idle but in the end its not enough and that's why the integral and proportional air flow tables exist. They will take over if the spark is unable to make corrections? In saying this I believe both spark over and under speed tables are equally as important as the air flow tables and in the end all the tables need to work together to achieve a stable idle?

I've seen guys that completely delete the proportional air flow tables and or set the error count very high so it wont use proportional and relies entirely on integral.

I just don't know if this is the right way to do things?

[edcmat-l1]

I don't want the throttle blade to have to control idle speed. It cannot make small enough changes. I want the blade to remain still (or as still as possible) and I want the spark to control the idle because it is much faster and can maintain a much more stable idle. Once you start moving the blade around trying to chase the idle speed, that's where you get into instability.

There's a lot of stuff written about "how-to" tune that I don't agree with. Open loop tuning for one. Changing things like throttle blade PIDs is another.

That being said, your idle instability is not due to the prop or integral needing adjusting. It is due to the shape of your VVE. That's where the root cause of your idle instability lies.

2009 Z06 VVE.jpg

[edcmat-l1]

I'll also add, when your base airflow tables are correct, and your injector data is correct, you'll have much less other stuff that you need to change to have a vehicle run as close to normal or "stock" as possible.

[Cringer]

I will throw in my 2 cents and I feel like I am in alignment with edcmat. In my view there are really three different idle tuning scenarios.

The first one is regular idle (which is driver not touching the throttle). This is fairly straight forward.

• Use OEM GM air PIDs and OEM over/under spark values (a 2014 Camaro SS works great).
• Use a middle of the road idle timing (12-15*)
• Get the correct min final airflow

The second scenario happens when you blip the throttle (in neutral or in gear) or coasting down as you drive. These are usually the difficult scenarios to iron out.

The third one is open loop cold idle surging.

[edcmat-l1]

I will throw in my 2 cents and I feel like I am in alignment with edcmat. In my view there are really three different idle tuning scenarios.

The first one is regular idle (which is driver not touching the throttle). This is fairly straight forward.

• Use OEM GM air PIDs and OEM over/under spark values (a 2014 Camaro SS works great).
• Use a middle of the road idle timing (12-15*)
• Get the correct min final airflow

The second scenario happens when you blip the throttle (in neutral or in gear) or coasting down as you drive. These are usually the difficult scenarios to iron out.

The third one is open loop cold idle surging.

And I believe all of those scenarios SHOULD be addressed without touching the PIDs. The PIDs control blade behavior, period. I don't ever want to encourage extra movement, period. If I want some "dashpot" on decel, there's other tables for that. If I need additional idle airflow for cold start/open loop idle, there's other tables for that. Leave the PIDs alone.

[smokeshow]

The throttle is part of idle whether you want it or not. Integral control can have a very light touch...just depends on how you tune it.

[edcmat-l1]

If you look through his data log you can see where it starts to vary the idle speed. At that point the trims are chopping at the fuel, the timing is oscillating and so is the throttle blade. The throttle blade is exacerbating the problem, not helping it. In this exact scenario it is more productive to slow down the blade or even hold it still and ONLY use the spark control to keep the idle speed as stable as possible. The blade cannot control the idle speed as accurately as the timing I don't care what you do with the prop tables.

I'd put most all of that stuff back to stock, fail the maf, put it in SD, dial in the VVE and make sure it runs perfectly in SD, then turn the MAF back on. Most of the time these C6 Zs run better in SD with a lopey cam. I'd probably leave it in SD.

[Allen Vos]

I don't want the throttle blade to have to control idle speed. It cannot make small enough changes. I want the blade to remain still (or as still as possible) and I want the spark to control the idle because it is much faster and can maintain a much more stable idle. Once you start moving the blade around trying to chase the idle speed, that's where you get into instability.

There's a lot of stuff written about "how-to" tune that I don't agree with. Open loop tuning for one. Changing things like throttle blade PIDs is another.

That being said, your idle instability is not due to the prop or integral needing adjusting. It is due to the shape of your VVE. That's where the root cause of your idle instability lies.

2009 Z06 VVE.jpg

I do understand that you want spark to control idle if at all possible but sometimes the throttle blade does need to be adjusted to compensate and keep a steady idle.

So relaxing the proportional and integral airflow tables as everyone suggests makes a lot of sense so it does not make the RPM oscillate.

I also understand that its important to let the cam "RUMP RUMP RUMP " so to speak and loosen things up a bit to allow it to do that as an aftermarket camshaft will never idle as stable as the original cam..

I'm totally aware I need to bring minimum air flow in line a bit better, but more importantly the startup airflow is off. When I can get to the car next week I will definilty be doing that, but with regards to my VE table. I only tuned it on the idle to at least get the VVE numbers to be somewhat close to the MAF and Dynamic airflow just to keep it running decently.

I will definelty get into more changing of the VVE table once I get a wideband, but I wanted to ask you, what exactly would you do to my VVE table to make it idle more stable for the time being?

I only want to get the idle part stabilized and then get into some proper logging and tuning with a wideband in the spring.

The things is my idle is extremely stable once the car is warmed up with very little oscillations.

I feel like the warm up settings need to be changed which is why I was looking at the overspeed ECT corrections.

I've also got the option to use a bit newer proportional and integral tables from 2013-2014 cars which would be a bit better tables than my 09 vette. Just don't know which is the best one to choose?

[edcmat-l1]

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.

[Allen Vos]

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.

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.

I do appreciate the feedback. This is how we all learn.

I have 2 Questions for you

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

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?

VVE was reading roughly 40% higher than MAF or Dynamic AF

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.

TBH I haven't looked into setting the VVE table much other than the basic tuning and I'm still learning on the VVE table.

[Allen Vos]

I will throw in my 2 cents and I feel like I am in alignment with edcmat. In my view there are really three different idle tuning scenarios.

The first one is regular idle (which is driver not touching the throttle). This is fairly straight forward.

• Use OEM GM air PIDs and OEM over/under spark values (a 2014 Camaro SS works great).
• Use a middle of the road idle timing (12-15*)
• Get the correct min final airflow

The second scenario happens when you blip the throttle (in neutral or in gear) or coasting down as you drive. These are usually the difficult scenarios to iron out.

The third one is open loop cold idle surging.

Hello Mr. Cringer. Thanks for chyming in.

Just to recap I have base idle ignition timing set at 16^
I have followed Big Mikes idle guide and found min air flow to be at 10 G/s which makes sense as you can see in the logs MAF is drawing 9.5G/s when the engine is hot.
My startup air flow was way to high in the cold startup areas and TBH was a bit of a mess lol. I did straighten it out but I am on vacation and wont be able to get to the car until end of next week.

Edcmat has indicated my VVE table is a bit wonky. I had used your method of STFT plus LTFT to trim the idle only which resulted in the peaks and valleys on the VVE map which sounds like what is causing my surging while the engine is warming up.

Note that the idle is very stable at operating temperature.

This is why I thought the issue may be in the Overspeed ECT correction table.

How would you recommend fixing the VVE table so it at least idles smooth without any oscillation's while its warming up?

I did read your write up recommending a 2014 Camaro SS airflow pids as well as overspeed and under speed tables.

I did try them but had better luck with the 2010 Cadillac CTSV tables.

I also seen it was recommended to use a 2013 Automatic Vette tables also

Keep in mind my car is a standard and I have noticed all your videos and guides are based on an automatic so I'm not 100% sure which one is right for me?