My 98 civic ex has a weird idle. It always drops and then comes up. when it drops its starts to get rough. it drops to like 500 or lower when it drops but it comes up eventually. ANyone know the problem or have expierenced this. I have a cat back, and an intake thats it.

 

bump

 

are you throwing any codes?

check out your IACV (Idle Air Control Valve)

 

Yupp, either clean you IACV, or go get a new one. It will fix the problem.

 

There arent any codes Where is the Iacv located? Is there any test i can do and how much do they normally go for.

 

actually I would say screw in the plastic idle adjust valve inside the FIV and then look to the IACV.