Scotty, I need your help. I have a 2005 Wrangler TJ X 4.0. My fuel trim at idle is -1.3 - 1.0 and at WOT the computer is indicating +34. The engine will not rev past 4K RPM’s. I have a very strong raw gas smell. I have replaced everything from the iac, TPS, air filter down to a full exhaust. The Jeep has 256k miles but the engine has been replaced. It has been to many shops and apparently no one can figure it out. I do have active fault codes for every 02 sensor. (Out of the blue). Replaced and will not clear. Could the PCM be failing?? I’m bored line putting this on a truck and sending it to you! Will not exceed 55mph
Intake gasket leaks are likely, as is a restricted catalytic converter.
Here's the thing: It seems like you've had mechanics who haven't done adequate diagnosis. Too many mechanics load up and fire "the parts cannon." Apart from very cheap interventions (such as gas and radiator caps, etc.), it's an incredibly expensive and frustrating way to go.
Find someone who will do a general inspection and NOT GUESS at what is wrong. If you get an accurate diagnosis, then the mechanic will have to GUARANTEE the results. Anything less, you're more likely dealing with incompetents or hacks.
BTW, at this point, it would probably behoove you to get a general inspection of the entire vehicle, before you put another dime into it. You may have reached the point of NEFR (Not Economically Feasible to Repair). See here: http://www.agcoauto.com/content/General_Inspection
Ok, seems like a dumb question but I have to ask. Did anyone replace the PCV valve and check its hose to the intake manifold to see if it's clogged or collapsed??
If it's stuck closed it will cause the computer to throw O2 sensor codes and P0171 & P0174 (lean codes).
It will result in pressure buildup in the crankcase and decreased engine performance.
The engine won't mind, maybe not even notice, at idle but as rpms/load increases, the engine won't like it.
No matter how healthy the engine is there will be crankcase gasses generated by the combustion (blow-by gasses) in the cylinders .
As load increases the PCV valve opens (the computer knows when this should happen and compensates) and those gasses are sucked into the intake manifold and into the combustion chambers and re-burned.
If the PCV valve is stuck closed it can't do that. Crankcase pressure builds and those smelly combustion gasses (oil too) start oozing out of any place they can.
OK, I'm almost done with the PCV valve but first let's look at the PCV valve positions and blow by gasses during different RPMs/loads.
My PCV valve rant concluded, and assuming it isn't the culprit it sounds like you have a fuel starvation issue going on.
At idle, fuel trims are fine ( about negative 1%). But as your demand for more fuel increases, it isn't being met.
(The computer is "maxed out" on its attempt to add more fuel (+34 fuel trim))
So is a sensor lying to the computer about how much airflow is entering the intake, or are your fuel pressure demands not being met during high rpms/load by the fuel pump or a restriction?
I'm pretty sure those jeeps don't have a MAF sensor, they just use a MAP sensor. So if the MAP sensor was faulty it could be the culprit.
The thing to do would be to observe the Fuel Pressure, MAP (Manifold Absolute Pressure), IAT (Intake Air Temp), ECT (Engine Coolant Temp), values and what the upstream O2 sensors' voltages are (is it "pegged down around 0.1 volts constantly reporting a lean condition) at higher rpms/load?
Put a scanner on that Jeep and tell us what you find.
Check for intake gasket leaks
