Still running bad

Car still won’t idle. Replaced IAC and it ran ok for a few days. Had a readout done. Here’s the results.

2002 Ford Escort ZX2

Definition : Fuel trim bank one condition

Explanation : The powertrain control module uses the oxygen sensor to calculate the Air/Fuel ratio of the engine. The computer has recognized a rich or lean condition on one engine bank only.

Probable cause : If bank one and two codes set together suspect fuel pressure or MAF (Mass Air Flow) sensor.

Oxygen sensor defective.

Ignition misfire-repair.

Fuel injector problem.

While driving, the engine will die when coming to a stop. Have to put the car in neutral and rev the engine to keep running.

Please help. Thank you.

A faulty MAF sensor can cause this problem. But before you replace this expensive component, you need to use a scanner that can give real-time monitoring data. So for example, at 100% throttle position if the MAF sensor only shows 80% air flow, there’s a problem with the MAF sensor. Otherwise, you’re just throwing parts at it.


Sorry about the IAC advice. Like Tester says, it would be better to do proper diagnostics at this point than to keep throwing parts at it.

Clean that MAF sensor (follow directions on can). See if your car is one that codes will clear with a 1 min. battery disconnect. This worked for my F-150 when I had a “too lean” code on one bank and has stayed away for several months now. One difference in my situation is that my truk exhibited no symptons.

Someone can correct me if I am wrong, but seeing that your car is a I4 you only have one Bank! Unless you have two upstream O2 sensors.

Does this result in you advising not to clean the MAF sensor?

No, It means you can’t rule out diagnostics of either or. If the OP pulls the plug on the O2 sensor, and the car runs normal without it plugged in (except the check engine light on), then that could be a indication of a bad o2 sensor, but not a certainty. Obviously only do this for a very short time for diagnostic purpose only because of possible catalytic converter damage if left unplugged.