2010 E38 LS3 Reduce below Idle Push in a Manual Trans Car

Hi, trying to find where that I can lower the amount of push that I get when lugging, like just below idle in 1st gear, examples would be entering the garage, or slow traffic, etc. Those times when you just don't want to push the clutch in. I don't like the steadily increasing push, but then I dont like the high rev for the split second after pushing in the clutch while doing this. It really starts pushing, harder, harder until it feels like it's adding 100-200lb/ft or torque, then you push the clutch in and it revs way up for a sec then comes back down.

With all of my other cars that had real idle control valves, they limited how much extra torque was applied so you could do this normally without all of the extra torque. A little is good, alot is annoying. Seems like there's no limit on these as stock.

I've 0'd these tables, nothing changed with the below idle push.. some made a slightly different idle quality but not much different:
Idle Proportional Airflow positive values, then 0'd the entire table, no change.
Then 0'd the Adaptive Idle Underspeed and Oversped RPM Error, no change
Then reduced Airflow/Throttle Follower Torque to 7, below 800rpm. Did nothing.
Integral/Airflow: 0'd this table. No Change except it idled a bit higher.



Thanks!!!

Have you tried reducing the in-gear airflow final minimum?

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Originally Posted by RobZL1

Have you tried reducing the in-gear airflow final minimum?

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This was going to be my suggestion also. You could start off by just subtracting 2 g/s of air from the whole table and see how much it effects it.

One way to figure out if this is your problem / solution is to watch you commanded throttle % while this is happening. If your commanded % is increasing and your not giving it throttle and your not below your idle RPM table settings then you know its just trying to meet the final minimum airflow settings.

My throttle does increase quite a bit when this is happening, while not touching the pedal so I know that's where it's coming from, just dont know how to reduce it, it's ridiculous.

This is only happening while below my idle setting, that's my point. I want to reduce the amount it increases, it seems to keep increasing like there's no limit until it crosses above idle setpoint.

I would think the airflow reading would be way up when this is happening since the throttle is opening and it's generating tons of power to fight me.

Because of this I start applying brakes in the driveway by the time I'm at the garage it's almost spinning tires on it's own, the alternative is pull into the garage at 5mph, or whatever 700rpm in 1st gear is, or slip the clutch non-stop which I never like doing.

And once below 700rpm idle setpoint it has to get above it to relax.. 675rpm isnt good enough it just keeps increasing until it sees a moment above 700rpm. So annoying.

Is there some kind of final idle airflow maximum? That seems like what I would need. Limit the amount of additional air allowed for idle correction.

What about ECM 12199 - Idle Integral Airflow Limits? They show Normal and Coastdown, with Low Limit -8 g/s and High Limit 7g/s for Normal.

My normal idle airflow is around 7 g/s.

if it said Idle Correction Airflow Limits then I'd be sure this is what I am looking for.

https://vcmstore.com.au/blogs/news/g...7-idle-control

Check out this page. Some good info that might help you make the adjustments you need.

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Originally Posted by WAK

https://vcmstore.com.au/blogs/news/g...7-idle-control

Check out this page. Some good info that might help you make the adjustments you need.

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thanks, I had Spark basically disabled long ago. I started looking at that idle torque table, and ended up 0'ing every table related to idle airflow on multiple pages. Nothing helped at idle, it still pushed, however one of these changes did make this push stop if I had the accel pedal pushed just a little bit, example if I wasnt touching the pedal then idle was 700rpm and lugging it in gear would make it push, but if I pressed the pedal just a bit, just enough to register change, then RPM would drop off of "idle", and sit around 500-600rpm, and no extra push was created from lugging. Normally this slight accell pedal change would make it rev up just a bit, but with these changes it basically kicked it out of controlled idle, and it was base idling somehow. But I cant get this to happen with the accel pedal at rest. Seems like if I could figure that out, it would be what I wanted to fix.

So I dont know. I feel like there's a table missing, or I'm missing a critical table somewhere, but I doubt it since I 0'd everything. There's also other things I've never been able to fix, like the ghost high idle for the first 60-90 seconds or whatever it is after start.

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Originally Posted by 10_SS

thanks, I had Spark basically disabled long ago. I started looking at that idle torque table, and ended up 0'ing every table related to idle airflow on multiple pages. Nothing helped at idle, it still pushed, however one of these changes did make this push stop if I had the accel pedal pushed just a little bit, example if I wasnt touching the pedal then idle was 700rpm and lugging it in gear would make it push, but if I pressed the pedal just a bit, just enough to register change, then RPM would drop off of "idle", and sit around 500-600rpm, and no extra push was created from lugging. Normally this slight accell pedal change would make it rev up just a bit, but with these changes it basically kicked it out of controlled idle, and it was base idling somehow. But I cant get this to happen with the accel pedal at rest. Seems like if I could figure that out, it would be what I wanted to fix.

So I dont know. I feel like there's a table missing, or I'm missing a critical table somewhere, but I doubt it since I 0'd everything. There's also other things I've never been able to fix, like the ghost high idle for the first 60-90 seconds or whatever it is after start.

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Your over looking a few things. The high idle after start up is an easy fix. There is "start up" air flow, you can adjust it based on time and engine temp.
You also need to look at the Electronic throttle data. ETC scalar is a big one, that tells the ECM the size of the throttle body and makes a big difference on how smooth it controls the air flow and idle.
Also go back and look at my reply about Airflow final minimum.... If you reduce that by a couple grams it will give you more "cushion" around your 700rpm idle.
The idle setting its self, you can fine tune that to temp and vehicle speed, have you looked at those?

It would help if you post a tune and log file when your having this issue.

Quote:

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Originally Posted by WAK

Your over looking a few things. The high idle after start up is an easy fix. There is "start up" air flow, you can adjust it based on time and engine temp.
You also need to look at the Electronic throttle data. ETC scalar is a big one, that tells the ECM the size of the throttle body and makes a big difference on how smooth it controls the air flow and idle.
Also go back and look at my reply about Airflow final minimum.... If you reduce that by a couple grams it will give you more "cushion" around your 700rpm idle.
The idle setting its self, you can fine tune that to temp and vehicle speed, have you looked at those?

It would help if you post a tune and log file when your having this issue.

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"Your over looking a few things. The high idle after start up is an easy fix. There is "start up" air flow, you can adjust it based on time and engine temp". I forgot I fixed this awhile ago.. ended up being that table was in C and not labeled with a unit, but other coolant tables like the one right next to it (Base Setpoint) are in F and they are labeled F. Seems like HPT could fix that pretty easy.

"Also go back and look at my reply about Airflow final minimum.... If you reduce that by a couple grams it will give you more "cushion" around your 700rpm idle. " I 0'd these tables. No difference. It did make a temp lower idle that it had to correct for though.

"The idle setting its self, you can fine tune that to temp and vehicle speed, have you looked at those?" Yes, it doesnt matter where idle is, once your below idle it starts pushing hard. There has to be a limit somewhere.

Attached a log and tune with it's annoyance. This is with most of idle stuff 0'd out. I have since moved the Min Idle Ref from 550 to 700, no difference. Also cold or warm coolant, doesn't matter.

0'ing some of the overspeed tables just made it float higher rpm for awhile... didnt work for under rpm though.

My point is, I want idle correction for a normal idle, since most of the time lets say it uses 2% of avail torque to do it. I just don't want it increasing to 20% torque. Some of the tables that seem like they would control this, don't do anything noticeable in reality.

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