OFT - Revs not dropping to idle after WOT and letting off gas

[justinco]

I have an odd situation that seemed to start after I got the car tuned on an OFT stg2 UEL 91oct map (car was dyno tuned by a tuner using that as the base).

This issue always happens when autocrossing, I have not reproduced on the street yet.

The scenario is this; I am charging into the finish box at WOT in 2nd gear. I cross the line and hit the brakes hard, depress the clutch pedal, and lift off the gas. As I am stopping quickly, the engine revs stay up, or float around 5-6k, while my foot is off the gas. The revs do not come down as they should, until after a couple seconds of being off the gas. When they do start to come down the revs drop slower than I would expect. So my car is nearly at a stop in the finish box, yet still revving pretty high, with no foot on the gas.

Any idea what might cause this? I will try to get a datalog once the weather clears up, but seems like it should be a simple problem to fix. I also vaguely notice this issue when turning the car off. As I turn the key off, the idle slowly drops down to 0, as opposed to going to 0 almost right away.

[FRSBRZGT86FAN]

Originally Posted by justinco

I have an odd situation that seemed to start after I got the car tuned on an OFT stg2 UEL 91oct map (car was dyno tuned by a tuner using that as the base).

This issue always happens when autocrossing, I have not reproduced on the street yet.

The scenario is this; I am charging into the finish box at WOT in 2nd gear. I cross the line and hit the brakes hard, depress the clutch pedal, and lift off the gas. As I am stopping quickly, the engine revs stay up, or float around 5-6k, while my foot is off the gas. The revs do not come down as they should, until after a couple seconds of being off the gas. When they do start to come down the revs drop slower than I would expect. So my car is nearly at a stop in the finish box, yet still revving pretty high, with no foot on the gas.

Any idea what might cause this? I will try to get a datalog once the weather clears up, but seems like it should be a simple problem to fix. I also vaguely notice this issue when turning the car off. As I turn the key off, the idle slowly drops down to 0, as opposed to going to 0 almost right away.

Why don't you go back to that tuner? It's an edited OFT tune meaning it was done in romraider, he/she should know what the issue is. Datalog anyway and post the logs here.

[steve99]

Flash the standard oft tune into the car
if it fixes the problem its a problem with the other tuners work

of its still a problem then it likey a hardware issue with the throttle sensor or throttle body or possibly maf sensor

it wont be related to oft, its jut a device to flash a tune

with oft you can log throttle (sensor input) and also throttle plate (throttle body) from memory

they should correlate fairly well.

[drift86]

Are you 100% sure you are not stepping on both the brake and the throttle with your right foot?

If you cover both the brake and throttle pedal with your right foot, then this won't happen under light braking, only under heavy braking when the brake pedal depresses below the accelerator.

[churchx]

Can that be something like flat foot shifting feature in this custom tune?

[perry753]

Originally Posted by churchx

Can that be something like flat foot shifting feature in this custom tune?

This sounds like the problem.

[justinco]

Originally Posted by drift86

Are you 100% sure you are not stepping on both the brake and the throttle with your right foot?

If you cover both the brake and throttle pedal with your right foot, then this won't happen under light braking, only under heavy braking when the brake pedal depresses below the accelerator.

I thought about that, but I wear narrow Puma's when driving and the pedals are not remotely close enough for me to hit both pedals at once.

I have had that problem happen on my BMW though, the pedals are much closer and makes heal/toe'ing simple.

Originally Posted by churchx

Can that be something like flat foot shifting feature in this custom tune?

Good thought, but unless flat foot shifting is in the base OFT Stg2 tune, then it probably is not activated. I do not know how or where you even activate that and we definitely didn't do it when the car was dyno tuned.

Hopefully I'll have more time to troubleshoot soon. I'll be out of town again for a week.

[DocWalt]

It's probably the built in protection feature that holds the throttle open so the cats don't get flooded with unburnt fuel when you free-rev. Stop pushing the clutch in after the finish line, there's no reason to take it out of gear or mash the clutch unless your club makes you literally stop and even then, just push the clutch in last second as if you were pulling up to a traffic light.

[Dru670]

It's probably the same issue Mustangs have hehe

[justinco]

Originally Posted by DocWalt

It's probably the built in protection feature that holds the throttle open so the cats don't get flooded with unburnt fuel when you free-rev. Stop pushing the clutch in after the finish line, there's no reason to take it out of gear or mash the clutch unless your club makes you literally stop and even then, just push the clutch in last second as if you were pulling up to a traffic light.

Weird, never heard of any built-in feature like that before.

We do literally have to stand on the brakes in the finish box and stop as quickly as possible. I will try to leave the clutch engaged longer, I feel like I did try that but don't remember exactly.

[DocWalt]

Originally Posted by justinco

Weird, never heard of any built-in feature like that before.

We do literally have to stand on the brakes in the finish box and stop as quickly as possible. I will try to leave the clutch engaged longer, I feel like I did try that but don't remember exactly.

Yeah, I've watched your videos, it looks like you've got plenty of space to slow down and off of the clutch.

FWIW, I've had the same behavior VERY rarely. It's certainly possible it's something weird in the tune or FFS got enabled somehow. Maybe your tuner has definition files missing those special OFT features and it may have been set inadvertently without either of your knowledge (which is awfully scary)?

[justinco]

Originally Posted by DocWalt

Yeah, I've watched your videos, it looks like you've got plenty of space to slow down and off of the clutch.

The finish box varies by event. And...I just realized I haven't uploaded my most recent event to my Youtube channel, doh. That event is what made me create this post because this issue happened a lot.

In that video footage, you can actually see the revs stay up as I'm stopping in the finish box. This particular event the safety workers were actually standing next to the stop box to make sure people stopped as quick as possible (it was kind of short). I'll try to edit and upload it tonight or tomorrow.

Originally Posted by DocWalt

FWIW, I've had the same behavior VERY rarely. It's certainly possible it's something weird in the tune or FFS got enabled somehow. Maybe your tuner has definition files missing those special OFT features and it may have been set inadvertently without either of your knowledge (which is awfully scary)?

Yea, could be. As far as I know, the tuner just adjusted fuel/timing off of the base OFT map.

I really need to find time to do some tests, datalog the current issue, flash the base map back and test, etc. Maybe this weekend...

[EastBayCanuck]

I've had something similar to this with my AT after getting OFH and uploading the stage 2 tune (base not new one). When using sports mode I'll get revs high when on hills and take foot off the gas and it seems to stick at 5k or even jump up for a bit and not come down for what seems like 20 seconds (probably a lot less actually but just seems longer when it's happening).

[invaliduser]

I'm getting this on my 2017. Both on stock tune and OFT beta. Never happened on my 2013 FRS.