Idle Air Control (valve)Unit, or the Mass Air Flow Sensor??

Question

I have a 2001 Ford Escape V6 3.0L. When it is cold started, it wants to stall but when it is warmed up for a while it is fine. I already changed the EGR valve and the DPFE sensor and no luck. Changed the spark plugs and the oil the other day and now the engine light came on with 3 codes, P0171, P0174 and P0304. I was wondering which I should change next, the Idle Air Control (valve)Unit, or the Mass Air Flow Sensor??

Answer 1

Ford has had a problem with the 3.0 liter engines when they are cold. The Intake gaskets actually leak air causing a lean run condition and stalling when cold.
Once the engine warms up, the metal expands and the vacuum leak goes away.
Retorque the upper plenium or replace the intake gaskets and your problem will go away. Also, be sure to wipe the carbon build up away from the throttle body Plate.

Answer 2

Codes indicate lean condition and misfire on #4 cylinder. Not sure that either the IAC or MAF would cure problem. MAF could be contaminated and lead to lean condition but, probably not because it only happens cold. Reccomend looking for vacuum leak probably near #4 cylinder.

Answer 3

Probably a bad iac, The electric motor mounts go bad and short the iacs out. I usually change the iac and pcm and re-program the pcm and unplu the motor mounts. To test the maf you need a scope, and even then testing is usually inconclusive. Ive never seen a tps go bad on a maxima.

Answer 4

you have a lean condition on banks 1 and 2 with a #4 cylinder misfire. i would check to make sure that the #4 plug wire is attached and seated properly, and maybe have it taken in to see if the air/fuel ratio is off

Answer 5

Actually, I used to struggle with these "emissions" parts issues util I went to the local auto parts and bought a scanner. What a huge help these are.