Zetec Problem - Focus ZX3

[Andy W.]

My wife's Focus is having problems. On a cold start, the engine starts right put and runs ok. Once it warms up the idle studders just above 750RPMs. During the summer the idle was rough but the car always started fine engine warm or cold. Now that it is starting to get cold again, it still starts up fine cold but after warming the car will turn over but won't hold idle. You have to hold the gas down to keep it running. If you leave it off for a hour it will start back up and run fine with the bad idle. The cold weather problem started in early spring, so I had it tuned up. Fluids, wires, plugs, belts, and clean the throttle body. The idle still sucked after the tune up. It has 100K+ miles but does not have any codes. I checked them last night and cleaned the IACV. I swapped the TPS and it still acted up. When I pull plug wires individually it gets worse, indicating that I do not have a misfire. My next option is to change the MAF, but I'm tired of wasting money on sensor's that aren't broken.

Any ideas?

Thanks,
-Andy

 

[Tony2005]

Not sure if the Intake Air Temperature (IAT) sensor is a separate sensor, but that should be checked.

Edit. What year, tranny, engine? If you have some PIDs (or real time live data), post it.
And when was the last time the PCV valve was changed?

 

[Andy W.]

Yes I'm digging up and old post.

The IAT is a sperate sensor.

01, 2.0 Zetec, Manual.

I've never changed or checked the PCV.

I can pull real data, what number would you like to see.

Thanks,
-Andy

 

[Tony2005]

...I can pull real data, what number would you like to see.
..

The works. . Actually, ECT, IAT, O2 sensor, MAF, ....Basically, numbers that I can check to see if something is amiss. And do post data after it is "warmed up" when it is just about to studder or during "studder" event. I'll look through it tonight.

 

[Andy W.]

I'll try and pull the data tonight, cold and when the idle falters.
Thanks,
-Andy