Ok guys before you say anything I've already searched this out. Here's whats going on. I put a 2002 accord f23a4 engine in my 99 cl. I'm using the original motor's throttle body, iac, exhaust manifold. when I started the motor the it started reving up and down. I automatically thought fitv under the throttle body, but then saw it didn't have one. I've changed the IACV, EGR, DIZZY, COOLANT TEMP sensor, I've check the tps sensor with my multimeter, tried a different throttle body, checked vaccum lines, checked the coolant level. I noticed I have a vaccum line not connected on the tranny, but can't figure out where it goes. I'm racking my brain with this one, any suggestions would be greatly appreciated. thanks

 

when you put your car into gear does it still idle like that?

 

just checked, yes it still idles crazy.

 

Might be a vacuum leak somewhere. Spray starter fluid around the TB, intake manifold gaskets and vacuum lines and see if you can affect the idle surge.

 

yep, sounds like a vacum leak somewhere, try plugging the line ,does it still do it? look for a port that has nothing on it

 

Stupid question, but did you make sure the wires are correct on the distributor housing?

 

I checked the plug wires- they were straight. I plugged the vacuum line on the tranny and it didn't make a difference.

I tried the starter fluid but really couldn't find a change in idle. I did manage to lose my eyebrows when the starter fluid that was collecting on the intake manifold burst into flames! Thank God the fire went out quick, I inspected everything-no burn damage.

When I put my finger over the hole in the throttle body and regulate how much air it sucks, the idle drops to normal.

 

looks like a tps problem, do you have a cel?

 

no cel.

 

Check PCV valve. If it's stuck wide open or disconnected, it can cause this loping idle.

good luck

 

i've changed pcv and pcv hose. its probably something minor, I can't wait to figure it out.

 

figured it out- it was a stuck iac valve. thanks for posting and trying to help.