My car is misfiring on cold start. It is not throwing any misfire CEL's, and the misfire seems to be very slight, but enough to make the idle a little rough. It runs perfect when driving it cold, and the misfire only lasts for about 2 minutes (if I just let it sit and idle), and after 2 minutes it runs PERFECT.

Then as soon as it reaches operating temp the CEL comes on, I am getting a code for knock sensor and IAT. This may not be related, but I figured I would throw that out there.

Oh, btw, I just swapped this in there last weekend, and the motor/ecu (p30) is from hmotorsonline.

This is a OBD1 B16 in a 98 civic.

Any help appreciated, thanks

 

fix check engine light issues first. if ther is an issue with the iat would def. make for some issues. the knock could be coming from the misfire issue.

 

Thanks. That makes sense. Hopefully a new IAT will solve my cel & idle problem.