revs hanging
 

I'm having a issue where when i rev my car mainly at idle sometimes the revs will hang. So say i rev to 3k then let off my rpms stay where they are. I checked to see if anything is obstructing the thrttotle body but it works just fine. This also happens during driving. Say around 4k rpms when i let the gas off it will ghost cruise for like 2 mins then rpms fall off after i push in the clutch. Any ideas on this one? And not to mention but even the idle seems off at times revving to 2k rpms when i come to a stop then after 2 mins or so dropping to normal.

try pushing in the clutch and letting it out again when this happens.

it hangs there because the car thinks your going to shift.

There are a couple of functions at work here. When stopped: It always seemed like the car "blipped" the throttle on rev down from the 2-step on the 15 rom right before it got to idle to make sure the car didn't die. On the 20 rom it seems to hold the RPM 2-3 times on the way down.

When cruising... if you have just been on the throttle at all you will get some hang because the car delays when it initiates fuel cut.

MIVEC changes might help, and if a fance disassembler figures out the decel fuel cut routines adjusting those can help. In the CT9A world it was the ISCV, but I don't think thats the case any longer.

There are a few threads on this topic here. Maybe some of them can give you more information but thats about it.

There is a TSB for this. Basically they Reprogram the Engine ECU. The whole point of the idle hanging is to cool down the cat. converter after driving with a more than "feather" foot. TSB-08-13-005REV

When did the TSB come out? Can the dealer flash this to my ECU even though i have a tune?

you will lose your tune, because it reprograms the EECU. It came out sometime in late 2008 I believe

Do you know the ROMID by chance?

Hmm, actually I think it's the other way around.

The overrun continues to run an air/fuel mix through the exhaust stream to keep the cat "lit" (i.e. hot enough to maintain its job of post-combustion) when you get back on the throttle.

is this tsb for canada only? the last time i went to a dealer about the rev hang, they said its normal and didn't mention any tsb or anything.

The TSb is for north america i believe. See my post in lancer general about accessing TSB's

This TSB was released Sept of 2008 and supersedes TSB 08-13-005 of April 2008

Stoked - I am not aware of what a "ROMID" is. And I may be wrong what the reasoning for this idle hang is, but in the TSB it states-

"The condition is due to parameters within the ECM that control engine speed to protect the catalytic convertor when it is very hot"

So I am assuming this is to keep exhaust flow to cool it down.

Example:

I work on heavy duty trucks, and new emission laws require having a filter, to filter out soot from the diesel exhaust. Now the truck does a self cleaning of the filter. This requires very high exhaust temperatures (1100 degrees F) When it is done doing a "regeneration" You are advised to let the truck run to cool down the exhaust components. This is done more quickly if you are at 1500 RPM rather than 650 (idle) BTW a trucks max RPM is 2200 approx.

So i believe the same principle is done with a cat in a car...if its hot, let the engine pass more cooler exhaust through it rather than the hot exhaust created by heavy load from an engine. If i missed something or am confusing..let me know ;)

Hope this explains...any more questions don't hesitate

Your friendly mechanic,

Camshaft ;)

Looks like Ill be taking a trip to the dealer then back to RRE to have them reflash my tune. The hanging revs, pisses me off.

I had my ECU updated at the dealer and it did not cure this issue... it is very annoying

But was it the programming for this TSB? There are many different software configurations for every engine ECU.

My buddies car had the same problem, his tuner thought at first that it was the intake he had on the car, that the fan in the front was blowing air back in the intake when he was at a stop causing it to rev high (about 2k) and would drop after a few minutes. This was NOT the problem. Mike at road race engineer thought that he might of been boosting too much, he was tuned at 26lbs, so after he turned his boost down a little about 2lbs his car was back to normal..

Do you have a manuel boost controller??