Idle drops low after rev and comes back up?
 

So ill be driving down the road and whenever I push in the clutch to coast or shift gears the idle drops down low and jumps back up to normal everytime, it starts to do it when the car is starting to get warmed up and gets warmed up and doesnt do it when its cold. Or if the cars in neutral and I rev it up, when it starts to come down from reving up it drops low and comes back up to normal. When it does it I can feel the motor vibrating as if it almost stalls but it doesnt, the idle just goes low and comes back up... whats the cause? please help! just started today......

**Ive messed with the idle adjustment screw all different ways and still no change....**

Re: Idle drops low after rev and comes back up?
 

bump... ive tried every other forum and no one can help!

Re: Idle drops low after rev and comes back up?
 

well, i'd probably start with the basics. check ignition timing and engine vacuum. that's what i'd do.
how is the idle otherwise? does it fluctuate at all? what is it set at?
what car/engine is this?

Re: Idle drops low after rev and comes back up?
 

My car does this too and so does my sisters stock 2005 EM2. Drops to 500 rpm and goes back up to 7-900 rpm. This too happens when coasting when putting the clutch in and foot off the gas. This does not happen when our engines are cold either.

Re: Idle drops low after rev and comes back up?
 

Sounds normal to me. My ef and my dc do it....... no issues. Now I could see an issue if the car stalled out every time it did it...

Re: Idle drops low after rev and comes back up?
 

this is almost considered "normal" when it comes to hondas....my DC2 does it...

if its excessive check the butterfly diaphram (if equipped with stock intake) if that hose isnt connected that could cause it

Re: Idle drops low after rev and comes back up?
 

mine does it also but check your IACV may be the issue because I need a new one so take it off and clean it with break cleaner. but it can also be a vacuum like the other guy said.

Re: Idle drops low after rev and comes back up?
 

No biggy

Re: Idle drops low after rev and comes back up?
 

Hi d0wnShiFt! Were you able to figure out what's causing the rpm to drop after revving?

Re: Idle drops low after rev and comes back up?
 

Re: Idle drops low after rev and comes back up?
 

another possible solution is to clean the Idle Air control valve(IACV) using a mass air flow cleaner to remove carbon build up and sticky dirt.

Re: Idle drops low after rev and comes back up?
 

Old tread. 94

Re: Idle drops low after rev and comes back up?
 

IACV needs repair

Re: Idle drops low after rev and comes back up?
 

Try your brake booster. I have a 90 integra da and it also has rough low idle. It only acts up when decreasing speed or at a stop when pressing on brake