M/T Supra Rev hang

[Sivleton]

Hi everyone,


I’ve been driving my M/T Supra for three years now and I absolutely love it, but there’s one thing that’s been bothering me: the rev hang. Specifically, how slowly the RPMs drop when the clutch is depressed during upshifts.


Some people claim the issue lies with the Dual Mass Flywheel, while others say it’s down to the throttle mapping when the clutch is in. Can anyone weigh in on this? Has anyone here already switched to a single-mass flywheel, and if so, did it help? Is there any other way to get rid of this?


I’ve already done the CDV delete, but it didn't make a difference.

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[swrdply400mrelay]

Turning off rev matching seems to help slightly.

 

[lucky phil]

Hi everyone,


I’ve been driving my M/T Supra for three years now and I absolutely love it, but there’s one thing that’s been bothering me: the rev hang. Specifically, how slowly the RPMs drop when the clutch is depressed during upshifts.


Some people claim the issue lies with the Dual Mass Flywheel, while others say it’s down to the throttle mapping when the clutch is in. Can anyone weigh in on this? Has anyone here already switched to a single-mass flywheel, and if so, did it help? Is there any other way to get rid of this?


I’ve already done the CDV delete, but it didn't make a difference.

Rev hang is about the mapping, nothing else. It's an emission reduction strategy. Same on many manual cars.
Phil

 

[Sivleton]

Rev hang is about the mapping, nothing else. It's an emission reduction strategy. Same on many manual cars.
Phil

If so can it be tuned out? Like changing throttle mapping when in neutral (clutch in)?

 

[Sivleton]

Turning off rev matching seems to help slightly.

With rev hang ? I think it is not changing anything for upshifts.

 

[Hasan]

Theoretically, a lighter flywheel should help.

 

[lucky phil]

Theoretically, a lighter flywheel should help.

Not if the mapping doesn't shut the throttle plate in fast response to the throttle pedal movement. Thats why his single mass flywheel hasn't worked.
Phil

 

[lucky phil]

If so can it be tuned out? Like changing throttle mapping when in neutral (clutch in)?

Yes. It's about the rate the throttle is allowed to close when you lift off to reduce hydrocarbon emissions. It's not a Supra specific issue as many modern manual cars suffer from it and have for years. The precise control via the clutch switch I don't know about and most of the expertise here is on the auto cars but there are people here with the ability to solve the issue via tuning if those people put their resources to the task for the manual cars. Strangely my car doesn't suffer from the issue so it may be something specific in the tune for different regions.
Phil

 

[Sivleton]

Yes. It's about the rate the throttle is allowed to close when you lift off to reduce hydrocarbon emissions. It's not a Supra specific issue as many modern manual cars suffer from it and have for years. The precise control via the clutch switch I don't know about and most of the expertise here is on the auto cars but there are people here with the ability to solve the issue via tuning if those people put their resources to the task for the manual cars. Strangely my car doesn't suffer from the issue so it may be something specific in the tune for different regions.
Phil

It certainly is region specific. I have EU version so i guess it is much more eco oem tune. By the way i read that throttle body in B58 is 90% open all the time couse its vavletronic that do all the intake work and throttle body is there only for cold start and as a valvetronic failsafe.

 

[Lorre]

I find that it is not as bad as some of the other modern manual cars I've driven and owned. I find that I only really think about it during the 1st to 2nd shift. The rest are ok for me.

GR Yaris is quite a lot worse in comparison.



A single mass lightweight flywheel does seem to help but it brings about other considerations such as clutch chatter and moving off etc etc.

 

[lucky phil]

It certainly is region specific. I have EU version so i guess it is much more eco oem tune. By the way i read that throttle body in B58 is 90% open all the time couse its vavletronic that do all the intake work and throttle body is there only for cold start and as a valvetronic failsafe.

Yes I was reading that yesterday as well, surprising. I need to do more research. Maybe the guys that are heavily into the tuning and logging can shed some light.
Phil

 

[Hasan]

Not if the mapping doesn't shut the throttle plate in fast response to the throttle pedal movement. Thats why his single mass flywheel hasn't worked.
Phil

He hasn't tried the single mass flywheel.

Apart from the ECU calibration there is also the big drop in gearing between the first and second gear.

 

[lucky phil]

He hasn't tried the single mass flywheel.

Apart from the ECU calibration there is also the big drop in gearing between the first and second gear.

Yes true I misread his post and thought he had already fitted the light flywheel. You are also right about the large jump between first and second but thats not going to affect the rev hang which most define as the engine not immediately losing rpm once you get off the throttle during the shift. It's does affect the shift action though. The wider the ration jump the harder the syncros need to work.

 

[Hasan]

Yea. Whatever the cause, 1-2-3 shifts are horrible.

 

[lucky phil]

Yea. Whatever the cause, 1-2-3 shifts are horrible.

Mine shifts absolutely fine and it's 100% stock.
Phil

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