brianm_96gt

It only stalls when pushing the peddle to the floor. Gradual acceleration it isn't as prevalent. It trips codes 171 & 174. It doesn't happen all of the time either. I changed the fuel filter and that didn't help. When the ford dealership looked at it he said he didn't think it was an O2 because it looked fine on some sort of short term reading but the long term was showing them leaning out. Couldn't suggest anything but to start changing parts. I would at least like to be able to have some idea if the problem is bad before changing. Any help on what to check would be a great help.

Thanks,

Brian

 

BARTMAN6

Check for leaking air hoses, especially the PCV. A common problem is a crack in a 90 degree bend in the pcv hose at the rear top of the engine. Hard to see until you stick your hands back there and start moving things around. My problem was the pcv valve popped out of the valve cover.

From what I have read, sometimes a bad Mass airflow sensor can cause these codes. It is about $130 part to replace yourself and easy to do. There are ways of checking it first with a voltmeter, but I do not know the procedure.

Lanceairauto

This may be posted a bit late, but it's better to have some info rather than no info. I recently worked on a 2002 Merc Sable V6 which exhibited DTC codes 171 & 174. After some basic system and component checking I found the crankcase vent tube 90 degree elbow deteriorated and broken in half. This elbow was the one located on the back side valve cover...hard to see. A situation like that can certainly cause a lean condition by sucking large amounts of unmetered air into the cylinders.