Throttle "hanging" open during autocross/track days

[Brake_L8]

I'm putting this in the track/auto-x section because I've only noticed it during those types of events. I've had my E82 at VIR, and this weekend, a BMW CCA autocross. Both times, I've noticed that the throttle will feel as though it's sticking open for about half a second after I lift from the pedal.

This is with the car in gear and at higher RPMs. I'll want to be lifting throttle and applying brakes, and you can feel the car still pulling forward as you apply the brakes.

DTC is fully disabled (holding button for 5 seconds, full Tim Yoyo mode).

I don't track/autocross this car hardly at all, but it's a bit unnerving to feel this. Would a tune make the throttle response sharper and more accurate?

[Kgolf31]

Originally Posted by Brake_L8

I'm putting this in the track/auto-x section because I've only noticed it during those types of events. I've had my E82 at VIR, and this weekend, a BMW CCA autocross. Both times, I've noticed that the throttle will feel as though it's sticking open for about half a second after I lift from the pedal.

This is with the car in gear and at higher RPMs. I'll want to be lifting throttle and applying brakes, and you can feel the car still pulling forward as you apply the brakes.

DTC is fully disabled (holding button for 5 seconds, full Tim Yoyo mode).

I don't track/autocross this car hardly at all, but it's a bit unnerving to feel this. Would a tune make the throttle response sharper and more accurate?

I have data to support this.

Watch the THR% at the top, that is my throttle position.

When I get off the throttle, you'll see that it goes to around 10% and slowly decreases after that. Especially after the finish, you can see it slowly decrease to 0%

I do have an AA Tune, and I can say for a fact it has helped the issue great. However it still isn't resolved. AA believes that this issue is due to trying to get good fuel economy and emissions related.


Sorry I can't help more, but I've noticed it and I can prove that it is indeed apparent

[Brake_L8]

Huh, interesting. Well, I've thought about a tune (at some point... my M3 is far more needy right now) so at least I know it will help substantially, if not eliminate it completely. Thanks for the data!

[Kgolf31]

Originally Posted by Brake_L8

Huh, interesting. Well, I've thought about a tune (at some point... my M3 is far more needy right now) so at least I know it will help substantially, if not eliminate it completely. Thanks for the data!

I need to still go back to AA and show them the data. They made some changes without seeing this, so I'd say they understand where I'm coming from and there is progress.

I'll continue to update you if I get some changes on my car

[Ginger_Extract]

Rev hang is an emissions control devil. Modern Naturally Aspirated cars tend to showcase this more than boosted cars due to the differences in engine vacuum. You will notice the same thing when you clutch in, and the revs will linger before dropping. If you want a very clear example of it, do a quick google search on 06+ Civic Si rev-hang issues.

[chris82]

I posted a thread about this before after an HPDE I went to. I'll lift off the throttle and it's not quite reacting how it should. Do you have the N51 or N52 engine? Both me and @KGolf31 have the N51 and Active Autowerke tune. He got his fixed, and
now I'm thinking I need to get mine fixed as well. But You say you don't have a tune? I can't believe this is an issue on a stock motor.

God damn this makes me mad if it's due to emissions.

[Kgolf31]

Originally Posted by Chrisar82

I posted a thread about this before after an HPDE I went to. I'll lift off the throttle and it's not quite reacting how it should. Do you have the N51 or N52 engine? Both me and @KGolf31 have the N51 and Active Autowerke tune. He got his fixed, and
now I'm thinking I need to get mine fixed as well. But You say you don't have a tune? I can't believe this is an issue on a stock motor.

God damn this makes me mad if it's due to emissions.

I have a N51 w/a tune and even though the issue is reduced...it is still there (as you can see with the data).

Talked with AA and they said they are limited with how much they can do to fix a throttle issue.

[MightyMouseTech]

Originally Posted by Ginger_Extract

Rev hang is an emissions control devil. Modern Naturally Aspirated cars tend to showcase this more than boosted cars due to the differences in engine vacuum. You will notice the same thing when you clutch in, and the revs will linger before dropping. If you want a very clear example of it, do a quick google search on 06+ Civic Si rev-hang issues.

Exactly. I had an 06 Civic Si. Drove me nuts in stop and go traffic. Adding a KFlash Pro helped immensely.

Unfortunately, there will always be some to prevent a carbon spike in the exhaust emissions.

[chris82]

Originally Posted by Kgolf31

I have a N51 w/a tune and even though the issue is reduced...it is still there (as you can see with the data).

Talked with AA and they said they are limited with how much they can do to fix a throttle issue.

Ohh, I didn't know you had the problem without the tune. I thought it was when you got your original AA tune that it started happening?

[Brake_L8]

Originally Posted by Chrisar82

Ohh, I didn't know you had the problem without the tune. I thought it was when you got your original AA tune that it started happening?

Mine is a stock-tune N51 as well.

[Kgolf31]

Originally Posted by Chrisar82

Ohh, I didn't know you had the problem without the tune. I thought it was when you got your original AA tune that it started happening?

No, it was worse before the tune...much worse.

[chris82]

Originally Posted by Brake_L8

Mine is a stock-tune N51 as well.

Originally Posted by Kgolf31

No, it was worse before the tune...much worse.

Ugh, I'm starting to come to the conclusion that it's just the N51! Oh well, just got to get used to it I guess. Eventually I'll get Active to fix my tune.

[Brake_L8]

Originally Posted by Chrisar82

Ugh, I'm starting to come to the conclusion that it's just the N51! Oh well, just got to get used to it I guess. Eventually I'll get Active to fix my tune.

Yeah, seems that way. I don't really care given that I don't track the car, but I'll definitely try to have some of the lag/delay tuned out if I get an AA/Evolve tune on the car later on.

[pj.rodriguez]

I hate throttle hang. Girlfriend's VW MKV Rabbit does this. When shifting and putting the clutch in when you usually do, the revs climb like a mofo as if you pressed the clutch and your foot was on the gas still. I've learned to let off the gas almost a second before clutch because of this. When driving hard, it's annoying lol.

I had no clue it had to do with reducing carbon. How does that work exactly?

[chris82]

Originally Posted by pj.rodriguez

I hate throttle hang.
. . . .
I had no clue it had to do with reducing carbon. How does that work exactly?

+1 I'd like to know as well