jeffreylane
NAXJA Forum User
- Location
- Memphis, TN
Forst off, thanks for taking time to read this. I have read around the forum for quite some time now, but like most forums I read, I don't really post much. Warning, this is a long post, but I don't want to waste anyones time being redundant an things that I habe already tried.. I have a problem that has been whipping me pretty good lately. We have a 99 XJ 4.0 (auto) that had been running fine. Now it is barely running. The problem started about a month ago. We live inside the city, so this vehicle was rarely seeing over 45mph for quite a while. There was a roar in the rear (bearing or driveshaft), so I took it out on the interstate and took it up to about 75mph for a few miles, a few times (speeding up, then lettinh off to 55) to try and diagnose the roar. After exiting, I noticed that it was stumbleing at yhe stops. It seemes to get worse in the few mile trip through town to the house. After getting home, it idled terrible, but would smoth out ok while dribing until letting off the gas. I checked compression. All cylinders look good and pretty close. Clockspring had recently went bad, so after research, I unplugged it. No change. When I say no change, there was no change at any point I changed a part. It has however gotten progrssively worse along the way. I checked the TPS and it was out of range (guessing shorted from the bad clockspring). Only run "slightly" better after relacement, but now it test within range. Swapped the map sensor, cam sensor, crank sensor, no change. Went throgh fuel injector wiring, replaced the wires, as some were meltrd together, but I think just the insulation. Did noid test, everything fine but #3. About a year ago #3 driver had an internal short to ground I guess, and stayed grounded i stead of pulsing. I simply jumpered the #3 ground over to #5 and it ran fine. Been running fine over a year now. All other injecttors are getting a pulse and a steady 12v. I am getting codes for tps over and over voltage, and 1,3 and 6 injector. It is running extremely rich, as the new (1 week)spark plugs are dark sooty black just drom being cranked diagnosing in the driveway. new fuel pressure regulator, although a cheap one, but no change at all. Fuel pressure guage is very erratic, with needle fluctuatung very quickly between about 45 and 50, and then motor hesitages more (already running rough) and it quickly fluctuates between about 41 and 51ish. No loss in coolant. Oil smells and looks fine. Exhaust is very strong with white smoke, but no smell of coolant. Maybe Fuel pump assembly? Can valves make pressure fluctuate and have good compression? This one is stumping me, and any help would be greatly appreciated.
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