MEP

Hello folks, my daughters expo (she inherited it from me) with 200k miles just started pulling p0171 and p0174 codes. Clean the heck out of the MAF with new air cleaner, still pulling the codes. Tried the carb cleaner trick to find a vacuum leak and the engine did start running a bit faster when squirting the cleaner on the IAC.

Being FAR from a true mechanic I am not sure the IAC is creating the leak, any other ideas in this area before I start tearing into it?

RLXXI

Check the rubber elbows on the plastic lines going from the valve covers to the intake manifold, you may not see it but they usually suck a hole in the pit of the bend.

P.S. Welcome to the forum.

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white08gt

what exactly is the truck doing and what year? if it is idling low and rough the iac needs to come off and be cleaned. do not know if the problem you are having, on my 5.4 was a bitch to get to.

MEP

2001 Exp. We drive it infrequently now, mostly when my daughter is back from school. I did drive it once a couple of moths ago and it ran very rough for a minute or so then cleared up. She is running a little rough now, not terrible and something a lot of people would not notice. Need to pass emissions with the truck as well.

white08gt

iac will cause your idle to be real low, less than 500 rpms. will run find once you get going, pulling to a stop will have to put in in neutral to keep your foot on the gas to keep it running. if this is what is happening, just unplug electric connection and remove 2 bolts. clean it real good with brake cleaner, dry and install. a new one cost around $50 if the old is stuck. it is located on the back of intake manifold next to the firewall.

MEP

I just completed a smoke test on this and have smoke coming up from a hose next to the fire wall but also is being emitted from the IAC. Is this normal?