'99 p0171&p0174

[CheapThrills]

These codes are going to be the death of me. My truck started running rough before Christmas, so for my present I got new O2 sensors. Cleared the codes, stopped stalling, but then they came back. Replaced the fuel filter, cleared it. A day went by, then it came back again. I finally got my automotive teacher to diagnose it, and it was reading that the downstream O2 sensor (I only have one) was not reading on the PCM. So, I returned it, replaced it, and it still was not reading. I checked the PCV hose, it fit snug. I really don't have the money to spend on getting a new PCM, so is there any other things? Thanks.

 

[Sasquatch_Ryda]

What do you mean it was not reading? Where you monitoring the voltages or what?

Lean bank 1 and lean bank 2 codes on the 4.0L are 9 times out of 10 related to the intake gaskets. It is usually never related to the actual HEGO (o2) sensors.

Get a can or carb or brake cleaner and spray all along the upper/lower intake.

 

[pcollins]

Get MAF cleaner and clean your MAF sensor per instructions on the can. I had those two codes. CLeaned the MAF real good, cleared the codes, and they haven't come back yet.

 

[CheapThrills]

On the diagnostic computer, where it has live data, it was pulling up an N/A. And I've cleaned the MAF 3 times, loaded down with MAF cleaner. But right now, these codes are the least of my problems, alternator decided to not want to work.

 

[pcollins]

I hate to break it to ya, but it sounds exactly like you need a new PCM. or at least a different working one out of a JY. Other than that just check all your wires for shorts.

 

[CheapThrills]

I'm thinkin' about going to the junkyard, and getting that "tool box" item, to test it out. They don't have a lot of rangers my year/make/model, but it's worth a try.