Hey everyone.. Its been a few years. I'm back in the Ranger game.
I'm posting this from FRF, I posted there first because I thought the 4.0 section looked to be more active, but haven't gotten a response yet.
I just bought a 2006 FX4 Level 2 with 83k miles. I got it cheap, because it is running rough and is down on power.
I cleaned the mass air sensor with CRC MAF cleaner.
I have had a few codes come out of it, P0171 and P0174. I've done plenty of research and reading, in order to check out the common issues. I've read this thread.
If you have an 01+ 4.0 with lean codes (PO171 and/or PO174) look here! - Ford Ranger Forum
The PCV hose and elbows are all good. I did replace the PCV which did make a big difference, but it still running lean.
I have AutoEnginuity and the Ford package, so I scanned the Ranger, looking at the LongFT1/2 fuel trim PID's, as mentioned here.
Adaptive Fuel DTCs Diagnostic Techniques (P0171/P0174) - Ford Ranger Forum
(Really great write up)
Here is a screenshot of the values
So next up, I checked fuel pressure. Fuel pressure is excellent.. it idles at 65PSI, and when I turned the truck off, fuel pressure had only dropped to 60PSI after 20 seconds. The fuel filter has been changed.
So next up, I monitored those same fuel trim PIDs, and drove the truck down the road. With any amount of throttle, the fuel trims go down, closer to 0.
I'm not sure how well this chart will show up, otherwise I can post up the excel sheet.
The truck had an intake on it off of an older Ranger or explorer, with the different style MAF sensor, and likely leaked around the MAF. I replaced that with a Volant intake, to eliminate any vacuum leak due to the MAF not being sealed in the intake. Truck runs a little better but is still nowhere near as peppy or powerful as my old 01 4.0 was. I also picked up a new Motorcraft MAF sensor for $20 off ebay, and installed it. No difference.
Does anyone have any ideas? I guess I'm going to go around it with a can of ether and see if I can locate a vacuum leak, but that's my only idea besides throwing all new top end gaskets at it.