Could also be a bad Vapor Management Valve, or fuel in the Evap lines....

 

PO172 is the only code its ever had. I had a known good O2 sensor so I put that in to see what if anything happens. Going on a short trip on tuesday so i'LL drive it then.

 

The Ford Tech who worked on it the first time says he checked everything 2 times. The 02 sensor didnt help, so now I have had a PCM (used) laying here for 10 mo so i'm going to try it .

 

VMV test ok didnt see any fuel in the line, canister has no fuel in it. We have no idea what to do. CANT afford to spend any more $$. Didnt not clean the mass flow sensor, but didnt have it out and looked at when this problem 1st started.Fuel reg is in specs also. May take it to the auction this week, but the bank wont be happy on what it brings

 

For the fuel pressure regulator, remove the vacuum hose from it and watch for fuel to leak out of the regulator. The diaphram breaks and leaks fuel into the vacuum line.

If you have access to a scan tool, you can check the MAF sensor by watching your BARO pid. It should be around 154-155 Hz. Anything less(say 152 or less) is low.

Try test driving it, while watching some Pids. Monitor Short Term Fuel Trim 1 and 2, as well as Oxygen sensors Bank 1 and 2(the Upstream sensors). Monitor your Oxygen sensors, and watch for them to stick over .7 volts for longer then normal. When this happens watch STFT for that bank(I would stick to bank 1 since thats the problem bank). Does the O2 sensor stick rich, then the STFT goes negative? If so, you could have an intermittant failing O2 sensor. I've had GM products that exhibited random misfires on one bank or the other after warm-up. Come to find out the upstream o2 sensor was failing then causing a lean condition/misfire on that bank.

It's hard to tell you exactly how to diag it, without being there. There are different engine Pids you can monitor while driving or working on the hoist and certain readings you should expect to see. Try the above and get back to me. Any certain conditions it acts up more?

 

Its looks like it could be a bad VMV though it was "good" when checked before. Going to take one off another truck and try it.

 

You can close both the vent and vapor management valves with a scan tool, and monitor the FTP pid. If tank pressure starts to fall, or it pulls a vacuum, then the VMV is leaking and allowing engine vacuum to pull fumes into the intake.

 

It was the VMV drove it on a trip no light no codes. Thanks for the help

 

ITS baaaaaaaaaaaaaaaaaaaaack Code 172 was off for 2 weeks but only driven 100 miles or so, Salvage yard may be next stop

 

Another dealer tells me " WE HAVE NO IDEA ON WHAT TO DO TO FIX YOUR TRUCK EVERYTHING WE HAVE DONE AND WHAT FORD HAS TOLD US DIDNT HELP..............HERES THE $500 BILL HAVE A NICE DAY"

 

Cant even find a dealer that would give me much on trade. The all say FIX THE SERVICE ENGINE LIGHT. I would get forget it and drive it but it would be my luck that something would go wrong and cost me a fortune to fix it and I have little or no funds to spend on it anymore.

 

Let's think about RICH. Sure everyone will tell you too much fuel and they would right. Then everyone says your lean if you have a vacuum leak(too much air) and they're right again. But you can be RICH another way. What if the fuel is right, but you're not getting enough air for that amount of fuel. Your RICH. No one has told you that so far. What if air flow is restricted? Start at the air filter and follow the plenum all the way to the throttlebody. Your ex wife probably put a dead cat in there.

 

That's funny!

 

A air flow restriction of any kind would affect both banks the same . I would try swapping injectors from side to side to see if the problem follows . This would a no cost repair, or at the most the cost of injector o rings and a half hour of your time .