Rev Hang revisisted

[Leegamer]

Hey Everyone, I have done lots of searching on rev hang, including on this forum and have yet to find an easy fix. I've emailed the guy from Qrevs who will build a unit that can fix this, but it is a bit cost-prohibitive at 290$.

From the posts I've read people have tried throttle controllers but I haven't seen any convincing evidence that this resolves rev-hang. I've also seen people switching to cable throttle bodies, but having to use standalone ecu. At that point why not use the standalone ecu to control the dbw?

One thing I have not seen posted is that when the AC is turned on in my 2008 yaris the rev hang seems to completely disappear. Does anyone know if turning on the AC changes anything with the ecu or is it just the additional load that is causing the revs to drop faster?

If there is a change being made to the ECU I'm wondering if there would be a way to send that same signal to the ECU without actually turning on the AC. If this is possible you could essentially turn off rev-hang without applying the load of the AC that would reduce power/fuel economy.

If there are any threads on that specific theory please let me know, I couldn't find anything.

[SirDigby]

have you performed the throttle learn procedure? have you tried taking your foot off the accelerator before pushing the clutch pedal? i've only had this happen a few times when i first purchased my car, but i found these things really solved the issue and it has not happened in years. in the case of the a/c, it's probably the extra resistance on the belt bogging the belt enough that the rpm drop is assisted...

[Leegamer]

have you performed the throttle learn procedure? have you tried taking your foot off the accelerator before pushing the clutch pedal? i've only had this happen a few times when i first purchased my car, but i found these things really solved the issue and it has not happened in years. in the case of the a/c, it's probably the extra resistance on the belt bogging the belt enough that the rpm drop is assisted...

I am used to it now and release the throttle and then wait a split second before disengaging the clutch, but I still don't like it even after owning the car for more than 10 years.

What throttle learning procedure do you mean? I've had the battery unplugged dozens of times and have experienced the ecu learning process.

[Tinkerman]

To reduce Rev hang, I haven't done this on Yaris but did it in BMW.
Find the intake hose that feeds the ICV then reduce the size to it and you will drop rev like a rock.

[dogsridewith]

I know the shop manual has a list of abbreviations, but what and where is this ICV?

[Leegamer]

I know the shop manual has a list of abbreviations, but what and where is this ICV?

Idle Control Valve


To reduce Rev hang, I haven't done this on Yaris but did it in BMW.
Find the intake hose that feeds the ICV then reduce the size to it and you will drop rev like a rock.

Hey, it's worth a shot! Will try it next time I change my oil