99 Jeep xj wtf is wrong with it

meatheadwes

meatheadwes

Well-Known Member
Joined
Nov 8, 2009
Location
kings mountain
99 xj 4.0 runs like absolute sh*t. Was throwing crank and cam Correlation codes and now is throwing a p0351 coil a primary/secondary circuit code. I have changed both crank and cam sensor’s. Coil pack. Wire’s cap and rotor button. Swapped the ecm. And still having the same issue of misfires and want take fuel. Fuel pressure is fine. I’m at my wits end with this thing. Engine has 25k miles and was a daily driver weekend trail rig until a year ago when it stalled out on the way to go huntin. Got it runnin again and ran great. Then went to runnin bad Intermittently a few days later. Got irritated and let it sit for a year. Now it idles rough and can’t seem to get it figured out. Any insight would be appreciated.
 

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Has a p1391 intermittent loss of cmp or ckp and a p0138 02 circuit high voltage b1s2 pending codes
 
Have you checked the wiring going to each sensor?

I found the signal wire from my cps to be bad causing my 2000 cherokee to have weird issues. Another thing to check is make sure your injectors are working properly.
 
Keith1138 said:
Have you checked the wiring going to each sensor?

I found the signal wire from my cps to be bad causing my 2000 cherokee to have weird issues. Another thing to check is make sure your injectors are working properly.
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Did you test it out or find a break in it?
 
Jody Treadway said:
Inspect VERY CLOSELY where the engine harness wraps around behind the driver's rear head bolt(stud). It is prone to rubbing through and causing intermittent issues just like you're describing.
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I’ve looked at it. But I’m gonna go over it again to be sure
 
Check your distributor to make sure that there is not any play in it and that the bearing is not worn out. Also check the connections where the wires plug into the computer/ecm they could be corroded. :beer:good luck!
 
spraypaintman said:
Check your distributor to make sure that there is not any play in it and that the bearing is not worn out. Also check the connections where the wires plug into the computer/ecm they could be corroded. :beer:good luck!
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Everything checked out there. Made sure it hadn’t jumped time also
 
Have you used Google? 124,000 hits just on the PO351.
You changed crank and cam sensors. So .....

I did a couple minutes of reading and I'm gonna bet a nickle is sensor synch.
 
Others or Google can give you more info, but I assume the crank and cam sensors work together so they need to be timed a certain way.
 
As long as the distributor hasn't moved since it was running properly, the sync (cam/crank sensor sync) wouldn't be changed.
Try unplugging both O2 sensors and see what happens. I have seen failed downstream O2s cause similar fueling issues.
 
You said you changed the CPS, with what? I have burnt through numerous “new” CPS until I spent the few extra for a good oem and solved all my stalling, low power, bucking on acceleration, rough idle issues.
 
I attached the factory service manual for your 99 xj. If I were in your position, I would first clean all the engine grounds and pin out the harness back to the ECU. Also, the NTK O2 sensor are what these jeeps like. The 02 sensor up stream controls fueling, down stream only tells you if your cat is bad. If your Tach is bouncing around suspect would be CPS.
 

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Jody Treadway said:
As long as the distributor hasn't moved since it was running properly, the sync (cam/crank sensor sync) wouldn't be changed.
Try unplugging both O2 sensors and see what happens. I have seen failed downstream O2s cause similar fueling issues.
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I did have some o2 sensor codes back when it first started acting up
 
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