Hi Chuck here, HELP!!! (NUB)
1996 Grand Cherokee, 4.0L in-line six, Automatic 4WD
Anyway, jeep popping and powers down if throttle is pushed too hard. Got fault code P0171 (system too lean), also there is a fault in the message center (diagram of jeep center console) that says "coolant sensor bad" I got into things, here's what I did, changed 3 sensors (temp sensor front top of engine, air temp sensor on intake manifold, coolant level sensor in coolant reservoir) message center still says bad sensor??? Also changed, ignition wires, plugs, distributor cap and rotor, upstream and downstream o2 sensors, throttle position sensor, checked for vacuum leaks (none found, (looked hard)), discovered crack on exhaust manifold removed it and welded it. jeep runs a little better still pops once in a while. message center still says bad sensor. at my witts end don't know what else to do. Thanks in advance.

 

Sounds like, if the popping is at manifold, then it's still running lean. I'd say investigate the tank and the pump/filter assembly. There may be some crud in there. Idk..

 

I'm with VT, check your fuel pressure.

 

X3, check the fuel pressure.

 

Thanks, I will check the fuel pressure as soon as I find a gauge to borrow. I understand that it should have 49.5 psi or better. I plan on driving the jeep while checking the pressure and what it is when the engine pops and loses power. Going nuts with this. Will update after I get a gauge. Thanks again all, Chuck