I just bought my 1998 jeep cherokee 4.0 automatic about 2 weeks ago, was running fine for the first week and now its running like garbage, the CEL came on and I got it checked out. The code was PO171. The truck has 240k on the body and the previous owner said the motor was replaced and now this current one supposevely has around 80k on it. 2 days ago I did a full mopar tuneup, cap rotar plugs wires air filter and I reset the ECU. The truck was running great for about 15 hours and then on day 2 it was back to how it used to be. Running really rough. At idle my truck clanks around like it wants to stall but the RPMs are normal. The truck has a very strong fuel smell like it is running very rich and also the MPG are wayyy down. Any help on what I should do? This is my only veichle. Thankyouu
Is the engine light on again? If so is it the same code? Are you up to testing a couple of things? Did you replace the fuel filter too? You replaced plugs and wires correct? You will need a digital multi meter to run some test ok.
January, 29, 2013 AT 5:55 PM
Yes check engine light is back on, it is the same code, I cleaned my throttle body today nd blew out all the plugs attached. Still runs the same. I did not replace the fuel filter, no idea how to even check it. And yes I did put in a new cap plugs and wires during the tune up, my dad is an electrician and works on cars sometimes so I am sure he has a multi meter.
January, 30, 2013 AT 3:59 PM
I think I would start with the fuel filter it just infront of the gas tank. P0171 is lean condition bank 1 and this can be a lack of fuel by having a plugged fuel filter so thats why I say start there and you have never replaced it so it won't hurt to do it anyway and eliminate that as the cause ok. Once that is done see how it runs and let me know and we will go from there.
January, 30, 2013 AT 4:59 PM
1997-2001 cherokees have the fulter inside the tank, its part of the pump assembly. Cant afford to replace the pump or dump out 16 gallons of fuel with no where to put it all. Also the truck runs like garbage till I reset the ecu, once I reset it and start the truck back up it seem to run good for a few hours and then the next day its back to square one. That makes me feel like its an o2 sensor, I also checked all of my grounds and all the fuses to make shure the fuel pump fuse wasnt blown and its still basically new
February, 8, 2013 AT 3:58 PM
You have a standard cherokee or grand? On the grand cherokee it is just infront of the tank as I have 99 grand cherokee, on the standard cherokee it don't have an inline filter. With that yes it could be an o2 sensor. You don't have any vacuum leaks do you? If not then I will walk you though on testing the o2 if you want.