after a week, CEL back on a cold day...

[ThePhoenix]

So my CEL went away last week after cleaning the IAC throughly. It was cold when I cleaned it (cold for miami - about 60) and then it returned to high 70's...

today it went back to low 60's and the CEL came on about 1 minute after start up...after I started moving

do you guys think this is bad IAC or upper/lower intake gaskets need changing?

 

[gijoecam]

Instead of guessing, get the codes scanned. Most AutoZone stores will do it free of charge right there in the parking lot. There are literally hundreds of things that can cause the check engine light to come on. Without knowing which code is stored, it's a guessing game at best.

-Joe

 

[ThePhoenix]

its the same code...P0171 and P0174...sorry, I should have mentioned that. I am lean...I wish I was as lean as my engine is. TOO much air somehow

 

[gijoecam]

Aaah, OK... I thought there was more to it...

The service manual calls out a specific procedure for checking for vacuum leaks, but it involved viewing the powertrain PIDs, which is impossible without an NGS or WDS scanner.

The old-school method would be to spray brake cleaner around the upper and lower intake manifolds and vacuum lines listening for a change in the engine. Where you hit the vacuum leak with the brake cleaner, the engine RPMs will change.

Personally, I'd go ahead and swap out the lower intake manifold gaskets. With the proper tools, it shouldn't take a novice mechanic any more than a couple hours to do.

-Joe

 

[ThePhoenix]

but why would cleaning the IAC last week take care of it for a full week? its not like there was totally different weather...