revs while idling

Hi, All. I have a '94 Accord. When in park and idling, the engine revs up
and down with about once per second. rrrrrRRRRRRrrrrrrRRRRRRrrrrrrrRRRRRRR.
etc. Can't remember the RPMs, but at the peak, it's probably double the
normal idle RPMs.

What could the problem be?

Thanks,
Matt

 

This problem is often due to either low coolant, lack of coolant circulation
through certain valves/sensors, or trapped air in the coolant system.

You might want to read some of the prior threads where this problem has been
discussed before, for example http://tinyurl.com/3ac3w.

Eric

 

Approx 3 weeks after changing the head gasket on my wife's '95 Civic, I also
had this problem and discovered that there is what appears to be vacuum line
attachment assembly (about 2.5 x 4 inches) behind the fuel intake (top of
engine, center, near the fire wall). Two 10mm bolts had backed out and was
causing this. 5 minutes later everything was good again.

hope this helps.
David

 

Approx 3 weeks after changing the head gasket on my wife's '95 Civic I had
this problem develop as well. I discovered that the two 10mm bolts holding
the IAC (Idle Air Control) Valve on had backed out. 5 minutes later all was
good again. Oh yeah, this thing is located top center near the fire wall on
the air/fuel intake assembly. It's about 3 x 4.5 inches...

hope this helps...
David

 

I second that idea about low coolant. My 97 accord did the same after
it lost all the coolant due to a leak in the Radiator.

 

I also have a '94 Accord EX Coupe 2.2vtec. Mine revs for about 10min before
it gets warmed up. And also if I give it gas just after starting it up on a
cold day it revs up then goes down to about 900 and back up to about 1500
really fast. Is that what you mean? Also, I have a question for you......How
warm does your heat get?

 

I'd also check the EGR valve

 

you know icould also be a faulty o2 sensor. it happened to my car. high low
surging so i went to the garage of a friend of mine
tested my sensors and everything my o2 sensor was shot so i replaced it and
i havent had a problem since