5 second rev hang at low rpm

[J41v33]

So I recently went e85 (stage 2 e85 oft) on my car a few days ago, and I was having issues with my car idling (was happening with 91 as well but wasnt as bad), so I thought maybe the throttle body was dirty, so I took the intake tube off and discovered a bunch of gunk all over the back side and around the rim of the throttle plate. I took some throttle body cleaner and sprayed it down and wiped it up till it was clean. Did a reflash to reset the ecu and that idle issue went away.

But now when I drive off from first and then press my clutch in at around 2500rpm, the rev will hang there for almost 5 seconds before it even starts to go down.

my cars throw out bearing also started to make a supercharger type whine noise the same time this happened. Idk if it is all coincidence or what. Maybe I messed something up on my throttle body? I even noticed on oft after resetting my ecu, my throttle % was reaching 99% where before it was barely hitting 90%.

Things I tweaked on the e85 tune: cold start, tip in enrichment, and radiator fan. Not sure if any of those would have caused this weird rev hang issue. It’s been driving me nuts and idk what to do.
Someone help me!

[MRCA1ST]

How many miles on it? Sounds like you have some blow-by or something along those lines going on to get that level of buildup on the throttle plate. Do you have a catch can?

[steve99]

Originally Posted by J41v33

So I recently went e85 (stage 2 e85 oft) on my car a few days ago, and I was having issues with my car idling (was happening with 91 as well but wasnt as bad), so I thought maybe the throttle body was dirty, so I took the intake tube off and discovered a bunch of gunk all over the back side and around the rim of the throttle plate. I took some throttle body cleaner and sprayed it down and wiped it up till it was clean. Did a reflash to reset the ecu and that idle issue went away.

But now when I drive off from first and then press my clutch in at around 2500rpm, the rev will hang there for almost 5 seconds before it even starts to go down.

my cars throw out bearing also started to make a supercharger type whine noise the same time this happened. Idk if it is all coincidence or what. Maybe I messed something up on my throttle body? I even noticed on oft after resetting my ecu, my throttle % was reaching 99% where before it was barely hitting 90%.

Things I tweaked on the e85 tune: cold start, tip in enrichment, and radiator fan. Not sure if any of those would have caused this weird rev hang issue. It’s been driving me nuts and idk what to do.
Someone help me!

did you reduce both the maf correction after start in gear and in neutral tables. ?


if you don't it will idle rearly high when cold

[J41v33]

Originally Posted by MRCA1ST

How many miles on it? Sounds like you have some blow-by or something along those lines going on to get that level of buildup on the throttle plate. Do you have a catch can?

76k miles atm. The car idles like a dream now though so idk if its just the ecu trying to relearn everything again, but before when I would flash my ecu, it never did that during the relearn process. just ordered a catch can yesterday after the discovery

[J41v33]

good question lemme check that in a bit and ill get back. I'm at work right now.

but the thing is it still happens even when ive driven the car for over 20 minutes at operating temps.

[J41v33]

maf corrections were adjusted to the recommended values

[J41v33]

is it very easy to damage electronic throttle bodies? if its the throttle body that might be causing this maybe ill order a new one and see if that fixes it

[CoolHandMoss]

That same thing happened to me when my TOB went out. Because the TOB is no longer a bearing, it's just a metal sleeve after it fails, it puts drag on the engine. The engine will hold the revs up to prevent from stalling under the extra load. I thought it was just the car at first because the TOB went out as soon as I got it but when I fixed the TOB the revs started dropping straight to idle.

You could test that theory by just holding the revs up in nuetral without the clutch then releasing the gas and you'll notice that it acts exactly like it should.

[J41v33]

Originally Posted by J41v33

76k miles atm. The car idles like a dream now though so idk if its just the ecu trying to relearn everything again, but before when I would flash my ecu, it never did that during the relearn process. just ordered a catch can yesterday after the discovery

Originally Posted by CoolHandMoss

That same thing happened to me when my TOB went out. Because the TOB is no longer a bearing, it's just a metal sleeve after it fails, it puts drag on the engine. The engine will hold the revs up to prevent from stalling under the extra load. I thought it was just the car at first because the TOB went out as soon as I got it but when I fixed the TOB the revs started dropping straight to idle.

You could test that theory by just holding the revs up in nuetral without the clutch then releasing the gas and you'll notice that it acts exactly like it should.

I hope this is whats happening. My throw out bearing and clutch kit is coming in soon so I hope it fixes it. That could also explain my 2nd gear grinding issues.


Can anyone else confirm that this is the case?