protege revs while idling

[backmann]

I have a 2000 protege 1.6L, auto. When at idle the motor revs from 800 to 1100 then back to 800 then back to 1100..etc.. It also does it when I take my foot off the gas at 30 mph.
It doesn't do it when I accelerate and drives fine at high speeds on the highway. The timing belt was changed 2 months ago and we recently cleaned the ERG valve. Any ideas on the problem ?
Thanx !

 

[Kooldino]

Maf?

 

[chubbs]

vac leak, maybe that was my problem on my se-r. cant you spray like carb cleaner and if it ingests it running it revs.

 

[Kooldino]

Do you have a stock intake or no?

 

[KZL_99ES]

you have a lot of questions to answer...lol, sorry but it helps up figure out what could be wrong!

when exactly did this start to happen? right after your timing belt was changed?

 

[cougar10agREDUX]

Hook up a vac gauge. Idle vac should be around 18-22inHg. If its lower you have a vac leak. You said the egr was cleaned it may not have been properly installed or its faulty and all that gunk was keeping the valve sealed.

 

[backmann]

No stock intake .

It started to run rough after the timing belt was changed but the mechanic said the check engine light went on at the same time saying there was an EGR problem.

I'll get the mechanic to run a vacuum test as i don't have the equipment.
Thanx for all the help.

 

[cougar10agREDUX]

have him double check the timing belt. If its off it'll cause it to run rough

 

[justanothermp5]

def sounds like a vacuum leak but have them check the timing too just to be safe

 

[KZL_99ES]

yeah, your more than likely just one tooth off...sorry bud

 

[CulRidr]

Is it a constant pulsing or more random. I have the same issue (pulsing) and I'm almost positive it's the IAC valve. I put in a newer (old style) completely cleaned EGR, and there's no way the EGR would cause what my car does. Can't be bothered to clean it up in this cold weather, but I'll have that fixed in the spring.

 

[racecarjohnny]

its the mixture