Contour Enthusiasts Group Archives Forums General Troubleshooting P0171, P0174

The PCM will detect a leak about 1/20 of an inch, on 2000 and newer it is 1/40 of an inch. So the leak your looking for could be that small.

Secondly I had PO171 on a Zetec though and it was my injector O rings, finally found out they were leaking replaced them, problem was fixed.
The O rings would leak air on the intake stroke, creating a vacuum leak, causing the CEL.

So you have sprayed all around the gaskets, and the RPMs didnt change anytime at all, if they did change at all there is your leak.

Thanks, again, Hitman.
There was no significant decrease in rpm. I have been looking for the engine to stumble a bit. The rpm decrease would be very obvious if cleaner was sucked into a leak, right?
Is it reasonable to expect injector o-ring failure at 75K miles?
Jeez, I hope I don't have to remove the manifolds.
LLL

Does anyone know a mechanic (other than at a dealer) in the Los Angeles area that is familiar with these cars?

Did you reset the computer after hooking up the hose you missed?

If not, pull fuses 4 & 11 for a minute or so then reinsert. It's possible that the CEL is still on but you don't really have a lean condition any more??

I reset the codes at Autozone but they came back. Should I still re-set the computer? I assume you pull those fuses while the engine is off, yes?
Thanks,
LLL

Yes, pull the fuses with the engine off. These are the ones in the fuse box next to the battery btw.

Did that. Engine ran funky for a while, losing power at about 4K+. CEL came back after three cycles.
Back to troubleshooting.
Thanks for the suggestion, though.
LLL

OK. Was back to looking for a vacumn leak using the Haynes-suggested method of using a length of tubing as a stethoscope. Heard a faint hiss at the IAC, around the little nubby bit that points to the rear of the car. Then I blipped the throttle pretty hard and the damn thing moosed like crazy. Did that everytime rpms got high enough to open the secondaries. It even died once after the moose.
Could a leaking IAC valve be causing these codes? I assume that cleaning it won't fix a leak so it must be replaced. Before I run down to Star Ford and lay down $95 can anyone verify my conclusion?
Thanks, LLL

Is there such a thing as a leaking IAC valve?

Installed new IAC valve, re-set computer and so far so good. Engine seems to run stronger, even. Hope this improves fuel economuy some. Thanks to everyone for the help.
LLL