Engine not returning to Idle when rolling in neutral?

wmayhue

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Has anyone else experienced a problem where the vehicle does not return to a normal idle while rolling out of gear?
Just in the last few days, when I push in the clutch (Like slowing to a stop) and/or take the car out of gear, instead of returning to the normal ~700rpm, the engine stays at 1100-1200, and slowly increases rpm to about 1900, then drops back down to 1100 and repeats? Its almost like 'breathing' is the best way to describe it.

The odd part is, when the vehicle is not rolling, it returns to a perfect 700rpm idle.

Some information that may be relevant: I did allow the vehicle to warm up before driving, so the idle was around 700 before starting to drive. Ambient temperatures have been upper 30's and extremely wet and rainy these past few days.

I'm K-tuned on the base map, with the PRL Race MAF scaling option for the Cobra with Race MAF. Otherwise the car is bone stock, and I made no changes to the tune itself.

Haven't had a chance to drive around with my laptop and get some datalogging yet, as I have the Ktuner V1.2, but using the android app I checked my fuel trims, which are perfectly normal, and my knock control doesn't stray from .49 as I'm running 93 octane.

Any suggestions on where to start troubleshooting, or a specific parameter in the datalogging that would give away a mechanical or a tuning issue? Any advice is appreciated.
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Anjuna

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My best guess is that your MAF is off. When you're rolling, air is still pushing its way into the combustion chamber, which will push you're revs up and down. That's the only thing that I can think to explain the rolling revs vs the idle revs.

Otherwise I'd say maybe something is off with the clutch.
 

Tpancakes20

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Sounds like a similar issue to me I noticed it only happens if I touch the gas and try to move the revs surge like crazy between 800 to about 1500 then settles after a few times. also when I am moving the throttle seems way to sensitive unnaturally sensitive like when It touch it in gear it jerks the car hard not smooth at all.
 
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wmayhue

wmayhue

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Sounds like a similar issue to me I noticed it only happens if I touch the gas and try to move the revs surge like crazy between 800 to about 1500 then settles after a few times. also when I am moving the throttle seems way to sensitive unnaturally sensitive like when It touch it in gear it jerks the car hard not smooth at all.
Have you had any battery issues with your vehicle? Mine was plagued with a weak battery. I believe the engine is actually attempting to hold itself at higher RPMs to charge the battery. Built into the programming, similarly to how you have a high idle to warm the engine on a cold start.
Replaced my battery under warranty, immediately the issue was gone.
 

Tpancakes20

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Have you had any battery issues with your vehicle? Mine was plagued with a weak battery. I believe the engine is actually attempting to hold itself at higher RPMs to charge the battery. Built into the programming, similarly to how you have a high idle to warm the engine on a cold start.
Replaced my battery under warranty, immediately the issue was gone.
Maybe I crossed the terminals once by accident and blew a fuse but that being the only case. It runs fine on the +6psi tune but +9psi it gets funny.
 
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wmayhue

wmayhue

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Maybe I crossed the terminals once by accident and blew a fuse but that being the only case. It runs fine on the +6psi tune but +9psi it gets funny.
What modifications are you running? If they're all different then I would assume it could happen to a stock vehicle as well..
 

Tpancakes20

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What modifications are you running? If they're all different then I would assume it could happen to a stock vehicle as well..
27won cai and map catback is it I'm going to get some mass airflow cleaner and try that. I was cataloguing this morning and noticed off throttle and when ever revs drop the afr rockets to 26 to 29:1 and thats why the engine surges I think its trying to compensate.
 
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wmayhue

wmayhue

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27won cai and map catback is it I'm going to get some mass airflow cleaner and try that. I was cataloguing this morning and noticed off throttle and when ever revs drop the afr rockets to 26 to 29:1 and thats why the engine surges I think its trying to compensate.
That's interesting I'm only running the PRL race MAF housing with a Ktuner. I did some datalogging and didn't notice any changes in my AFR during the surges. After my issue went away I wrote it off as a battery issue considering all my logs looked normal
 

Tpancakes20

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That's interesting I'm only running the PRL race MAF housing with a Ktuner. I did some datalogging and didn't notice any changes in my AFR during the surges. After my issue went away I wrote it off as a battery issue considering all my logs looked normal
Thinking its a vacuum leak as I watch my boost gauge it doesnt want to drop back down to -10 when I take it out of gear and even in gear off throttle its reading -5,-6,-7. Which isn't normal I believe
 

SperrySi19

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Has anyone else experienced a problem where the vehicle does not return to a normal idle while rolling out of gear?
Just in the last few days, when I push in the clutch (Like slowing to a stop) and/or take the car out of gear, instead of returning to the normal ~700rpm, the engine stays at 1100-1200, and slowly increases rpm to about 1900, then drops back down to 1100 and repeats? Its almost like 'breathing' is the best way to describe it.

The odd part is, when the vehicle is not rolling, it returns to a perfect 700rpm idle.

Some information that may be relevant: I did allow the vehicle to warm up before driving, so the idle was around 700 before starting to drive. Ambient temperatures have been upper 30's and extremely wet and rainy these past few days.

I'm K-tuned on the base map, with the PRL Race MAF scaling option for the Cobra with Race MAF. Otherwise the car is bone stock, and I made no changes to the tune itself.

Haven't had a chance to drive around with my laptop and get some datalogging yet, as I have the Ktuner V1.2, but using the android app I checked my fuel trims, which are perfectly normal, and my knock control doesn't stray from .49 as I'm running 93 octane.

Any suggestions on where to start troubleshooting, or a specific parameter in the datalogging that would give away a mechanical or a tuning issue? Any advice is appreciated.
I had this exact same issue when I first used the Hondata flash pro. What was causing it was the throttle sensitivity. I tinkered with it in stage 1 and 2 and it did this exact phenomenon you’re talking about. When I set it back to default it stopped. To check I set it back to stage 1 and it did it again. So I left it on default. Check your throttle sensitivity settings.
 

USNengineman

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27won cai and map catback is it I'm going to get some mass airflow cleaner and try that. I was cataloguing this morning and noticed off throttle and when ever revs drop the afr rockets to 26 to 29:1 and thats why the engine surges I think its trying to compensate.
off throttle AFR goes to 29.1 if youre in gear. if you put it in neutral and coast your AFR should start at around 12.x and after a few seconds go up to targeted 14.7 and bounce closely around that.
so off throttle dont be scared of the 29.1
 
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