can't figure out idle problem

[lgardner55]

i've got an 93 accord ex 5spd and the throttle goes up and down when the engine is cold only. when it warms up it idles fine. i've changed the idle air control motor and i've changed the throttle position sensor. the check engine light never came on so i'm starting to think it was'nt electrical to start with. i put in a new thermostat and that did'nt solve the problem. the coolant seems to be flowing through the throttle body. the car was brought from an auction and it looks like there were some new gaskets installed under the fuel injection. i'm wondering was the wrong type of rtv silicone was used to throw off the ecm perhaps? help please!

[mydelsolrocks]

umm, to my knowledge, thats normal for a car to idle higher when cold...my sol did it and my acc does it....in fact....every car ive driven did it....i could be wrong but i think your acc is ok in that matter

[lgardner55]

Originally Posted by mydelsolrocks

umm, to my knowledge, thats normal for a car to idle higher when cold...my sol did it and my acc does it....in fact....every car ive driven did it....i could be wrong but i think your acc is ok in that matter

if you start the car while the engine is cold the idle goes up and down up and down up and down until the car starts to warm up then it levels out and idles fine! thats definitely not normal!!!!!

[MarcDavidoff]

You might have some air in your cooling system that is trapped by the IAC valve that you replaced. This can cause some idling issues

[94accordlx1]

do a full tune up, change o2 sensor the readjust the air screw it should be at 2000 RPM with cold start then normal when warmed up

[jeffcoslacker]

Originally Posted by MarcDavidoff

You might have some air in your cooling system that is trapped by the IAC valve that you replaced. This can cause some idling issues

Yup. That sounds like coolant surge over a temp sensor due to an air pocket, or the intake is sucking air when the motor is cold, and the ECM is hunting for a mixture and idle speed to compensate. You can mist around the motor with a spray bottle of water to check for a vacuum leak. If it sucks the water in, the idle will stabilize momentarily.

RTV can foul an oxygen sensor and cause problems, but the O2 sensor isn't active at cold start up, and shouldn't cause problems then. It has to get pretty warm before the ECM starts to accept it's signal.

I'd bleed the cooling system first to rule it out, then explore the vacuum leak possibility.