Of course he should test it, I was just saying. He's not buying the right parts at the right places.

 

No I hear you, just seems he wants to do all this other stuff but not test it. There are lots of ways to get OE parts without paying dealer prices.

FSM or Chilton's/Haynes should have the procedures for test8ng the MAF

 

I'm not resistant to testing just want to make sure I can do it right.

Good news is I found a video which also happens to be on the same vehicle.


Ran the tests and everything checked out good for the MAF. Power voltage was 12 volts and signal voltage was in specified range at idle and acceleration. Voltage movement was smooth during acceleration and deceleration.

When the pcv valve arrives I will replace it and see if that solves the problem.

 

There is a possibility that this was coincidental. The V6 plastic intakes have a tendency to need new plenum gaskets and isolator bolts. I've had to have that done on mine.

 

Wouldn't that show up as a vacuum leak? I didn't detect any vacuum leaks and the engine is running smoothly.

 

I would put my money on the isolator bolts. My 03 had about the same miles when the lean codes popped up and I was going about a sustained 75 mph, so much for the vac issue only at idle. The lean codes are from sucking extra air, so at high air demand (speed) the stress is on the gaskets and isolator bolts. Chances are it is not the manifold to head gaskets, but the rubber figure 8's between the plenum and manifold. The bolts are single use with the rubber plugs on them. It used to be that the Ford ones were the only way to go and they were very proud of them. I think that the Dorman ones have been improved now, but that's your choice.

2 other things to look at are the hose& pipe going to the PCV and and the hard plastic vac lines.

There are some write ups in the DIY, or search "isolator bolts ".

Good luck.

 

https://sites.google.com/site/fordf1...P0171P0174-Fix



https://www.tascaparts.com/oem-parts...hut-ef2z9j559d

 

This may be my problem. Is there any diagnostic to verify if this is the source of the air ?

 

Well, no luck..... Swapped out the pcv valves, cleared the codes and went for a test drive. CEL came back on, same codes - lean fuel banks 1 and 2. Similar freeze frame data.

So, the MAF is good, the pcv valve is good and a vacuum test on the engine did not indicate any leaks. Engine is running smooth and normal and I have a healthy, brightly lit CEL.

 

Read the link glc posted, that is a very good DIY.

 

That article deserves an award. I just wish there was a way to test that the plenum was indeed the problem. I hate to go thru all that and still have the original problem.

 

Use an unlit propane torch to look for vacuum leaks, when the propane is sucked in the fuel trims should change.

Note - exhaust leaks upstream of the O2 sensors can cause lean codes.

 

I was the same way with mine finally bit the bullet and parked the truck with 356,000 miles and never another lean code. I did the work at about 80,000 miles. It would be hard to detect with propane unless the plenum is cracked, but it's worth a try.

Good luck.

 

As I remember, I had about 120k on mine when the job was done. Mine was not tripping lean codes, it was a stuck IMRC code.

 

Update on my 171/174 codes....Problem solved!

I couldn't get past the coincidence of getting the lean fuel codes right after changing the MAF. So I removed the air intake duct downstream of the MAF and looked for cracks or damage in the ductwork. No damage found but I did see a rigid tube from the driver side valve cover to the air duct was not seated correctly. I also noticed the temperature sensor was not turned to be parallel to the air flow.

I corrected both, reassembled the air duct, cleared the codes and have driven about 50 miles with no CEL reappearing.

I think I have it solved.

Thanks to everyone for the help