Basics: 2000 XJ, 4.0, AW4, NP231, No significant engine modifications.
It all started about 4 weeks ago when I threw a Check Engine Light (CEL). I started a thread here about oxygen sensors:
http://www.naxja.org/forum/showthread.php?t=85229
I had figured that was the end of my electronical trouble for the time being. At the same time I had been stalling at idle, so I replaced my Idle Air Control (IAC) with a trail spare that I keep. Worked well as the stalling stopped. I also replace the MAP, and Throttle Posistion Sensor (TPS) while I had the throttle body off for cleaning. I threw on a spare TB and it had been running fine. Last week the CEL came on once again, and the same problem as in the thread above refering to oxygen sensor problems. So I took my 3 week old OS2 sensor back and exchanged it for a new one. Then I drove it up to the San Jose Basin just outside of Fresno for some mild wheeling (turned out to be pretty hard in places. One place in particular I had come down into what looked like a small mud puddle but turned out to be 3' deep. This might me part of the problem, but I doubt it because it ran fine for the next 2 days). Anyway back to the problem at hand. After the trip up to the mountains, I drove 180 miles to the coast to go to work. This morning I start it up and get about 2 miles off the ranch, and it starts to stumble and then dies, and throws a CEL. I start it back up and figure it is my Crank Posistion Sensor (CPS) or my TPS. I limp it home 10' at a time, every time I touched the gas pedal it sputtered, droped RPM's, then died. Once I get back to the shop, I changed out the TPS, IAC, and the MAP sensors one at a time to try to isolate the problem. No solution and now it wont start at all. So I order a new CPS and it will get here tomorrow. A good friend and a 30 year mechanic was out here working on one of the vinyard trucks offered some assistance. We hooked up the scanner and it returned these codes:
P1391: Intermittent Loss of CMP or CKP(Crank Shaft Sensor)
PO700: EATX Controller DTC Present
PO353: Ignition Coil #3 Primary Circuit
PO352: Ignition Coil #2 Primary Circuit
PO351: Ignition Coil #1 Primary Circuit
PO123: Accelerator Posistion Sensor (APPS) Signal Voltage too Low
At this point I am freaking out (what the *&%)!
We Start with the TPS and find that the computer is reading it at Wide Open Throttle (WOT). We check the wires that lead from the TPS to the PCM are fine and have no fluxuation when seperated from the PCM. We then come to the conclusion that the computer is shorted or fried. I take the PCM apart and it looked fine. All of the pins were clean and in shape. Then its Corona time to think. Then I want to check the TPS voltage (which should read at 5 volts, but had been reading at 5.94 volts) with the CPS disconnected. And low and behold it was reading dead on 5.0 volts. When I plugged the CPS back in the Shut down relay started to click over along with the electric fan. Then I quit messing with it until tomorrow. I guess my question is can a CPS cause all of this or is the motherboard toast? Anybody want to buy or trade for a well built 2000XJ as is? J/K. Any help on this would is greatly needed as this is a little much for a simple shade tree mechanic.
It all started about 4 weeks ago when I threw a Check Engine Light (CEL). I started a thread here about oxygen sensors:
http://www.naxja.org/forum/showthread.php?t=85229
I had figured that was the end of my electronical trouble for the time being. At the same time I had been stalling at idle, so I replaced my Idle Air Control (IAC) with a trail spare that I keep. Worked well as the stalling stopped. I also replace the MAP, and Throttle Posistion Sensor (TPS) while I had the throttle body off for cleaning. I threw on a spare TB and it had been running fine. Last week the CEL came on once again, and the same problem as in the thread above refering to oxygen sensor problems. So I took my 3 week old OS2 sensor back and exchanged it for a new one. Then I drove it up to the San Jose Basin just outside of Fresno for some mild wheeling (turned out to be pretty hard in places. One place in particular I had come down into what looked like a small mud puddle but turned out to be 3' deep. This might me part of the problem, but I doubt it because it ran fine for the next 2 days). Anyway back to the problem at hand. After the trip up to the mountains, I drove 180 miles to the coast to go to work. This morning I start it up and get about 2 miles off the ranch, and it starts to stumble and then dies, and throws a CEL. I start it back up and figure it is my Crank Posistion Sensor (CPS) or my TPS. I limp it home 10' at a time, every time I touched the gas pedal it sputtered, droped RPM's, then died. Once I get back to the shop, I changed out the TPS, IAC, and the MAP sensors one at a time to try to isolate the problem. No solution and now it wont start at all. So I order a new CPS and it will get here tomorrow. A good friend and a 30 year mechanic was out here working on one of the vinyard trucks offered some assistance. We hooked up the scanner and it returned these codes:
P1391: Intermittent Loss of CMP or CKP(Crank Shaft Sensor)
PO700: EATX Controller DTC Present
PO353: Ignition Coil #3 Primary Circuit
PO352: Ignition Coil #2 Primary Circuit
PO351: Ignition Coil #1 Primary Circuit
PO123: Accelerator Posistion Sensor (APPS) Signal Voltage too Low
At this point I am freaking out (what the *&%)!
We Start with the TPS and find that the computer is reading it at Wide Open Throttle (WOT). We check the wires that lead from the TPS to the PCM are fine and have no fluxuation when seperated from the PCM. We then come to the conclusion that the computer is shorted or fried. I take the PCM apart and it looked fine. All of the pins were clean and in shape. Then its Corona time to think. Then I want to check the TPS voltage (which should read at 5 volts, but had been reading at 5.94 volts) with the CPS disconnected. And low and behold it was reading dead on 5.0 volts. When I plugged the CPS back in the Shut down relay started to click over along with the electric fan. Then I quit messing with it until tomorrow. I guess my question is can a CPS cause all of this or is the motherboard toast? Anybody want to buy or trade for a well built 2000XJ as is? J/K. Any help on this would is greatly needed as this is a little much for a simple shade tree mechanic.
