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  #1  
Old August 9th, 2018, 20:59
deproson deproson is offline
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Loss of cam or crank sensors

So to start I have a 2001 Xj 4.0 auto 4WD.

I have been chasing multiple issues for months now and still I am not any closer to solving the issue.

I have a loss of cam or crank sensor code along with ignition coil circuit A B C performance.

My xj will run for about 30 seconds and then stall. When I say it runs I mean it runs at an idle fand fluctuates from about 300 rpm to about 850 rpm and dies after about 30 seconds. I have replaced the cam and crank sensor with Oem parts. That did not resolve the issue. I replaced the coil assembley, that did not fix it. I have continuity tested the whole engine harness and have found no issues with it.

I found a good deal for a engine harness and a known good ecm and I bought those and swapped them out and still no change.

I have also changed the timing chain set due to the higher mileage of my xj (260,000) miles.

I am a diesel mechanic by trade I know that the timing set was done correctly.

I know that the cam and crank are in sync. (Verified with snap on Zeus)

I did however make an observation while I had it connected to the snap on scanner, it would show while KOEO a status window that would say ďsync okĒ then switch to ďnot in syncĒ. Iím not that familiar with Jeeps and how they do things but to me that does not seem correct.

Iím running out of ideas and where to look. I feel like Iím chasing my tail. Any help with this would be greatly appriciated. I love my Jeep but after almost nine months of chasing this issue Iím about to give up and find a different Jeep.
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  #2  
Old August 10th, 2018, 00:37
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sidewaysstarion sidewaysstarion is offline
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Re: Loss of cam or crank sensors

Can your snap-on scanner see the crank and cam counters? Also have you tried a new coil rail?

Also you think I'm crazy, but try starting it without the accessory belt and see if it will run.
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  #3  
Old August 10th, 2018, 07:26
deproson deproson is offline
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Re: Loss of cam or crank sensors

Quote:
Originally Posted by sidewaysstarion View Post
Can your snap-on scanner see the crank and cam counters? Also have you tried a new coil rail?

Also you think I'm crazy, but try starting it without the accessory belt and see if it will run.
Yeah it seeís the counts. They appear to be what they should be. Crank goes to 160 and the cam hits 80 then the count starts over.

Iíll have to try the belt when I get a new crank sensor from the dealer. The dealer warrantied out the other oem crank sensor that I bought nine months ago. Considering that the Jeep never ran right since I swapped the oem sensors in I have a weird feeling that maybe I got a bad sensor out of the box straight from Jeep.
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Old August 10th, 2018, 07:30
deproson deproson is offline
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Re: Loss of cam or crank sensors

Quote:
Originally Posted by sidewaysstarion View Post
Can your snap-on scanner see the crank and cam counters? Also have you tried a new coil rail?

Also you think I'm crazy, but try starting it without the accessory belt and see if it will run.
Yes I have a brand new coil rail on it. Also oem.
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  #5  
Old September 14th, 2018, 17:03
deproson deproson is offline
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Loss of cam or crank sensors

Update:

My jeep is finally running after going through multiple OEM crank sensors. Keeps runs great now but I now have a different issue.

The issue that I have now is that after I did a hard reset on the ECM I can drive 80 miles with no problem. Then after I go 80.1 miles I get a check engine light then a flashing check engine light.

Checked DTCs

Cylinder 1 misfire
Cylinder 2 misfire
Multiple cylinder misfire

I have a spare good working ECM. Plug it in and can go another 80 miles problem free.

So is there anyone out there that can make any sense of this? I have never ran across anything like it.

Any help would be appreciated.


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  #6  
Old September 14th, 2018, 17:39
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Tim_MN Tim_MN is offline
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Re: Loss of cam or crank sensors

The hard re-set deletes the PCM adaptive memory and the PCM runs on pre-programmed baseline data. 80.1 miles is probably when the PCM has gathered enough data to use the adaptive memory. I doubt that you have fully fixed the root cause of the symptoms.

What were the original CEL trouble codes ?

Have you seen this ( http://jeep.blackonyx.net/pdfs/jcss.pdf ) and does your SnapOn display the cam and crank signals in the same manner ?




P1391 - Intermittent Loss of CMP or CKP Signal. Loss of the Cam Position Sensor or Crank Position sensor signal has occurred.
P1391 – Possible symptoms:
(1) random misfire/stumble/bucking/stalling, often over bumps or right hand turns or when going into reverse.
(2) shorted out the Fuel pump/ECU power wire.

Possible causes
- Faulty Camshaft Position (CMP) Sensor
- Camshaft Position (CMP) Sensor harness is open or shorted
- Camshaft Position (CMP) Sensor circuit poor electrical connection.
- CMP SENSOR OUT OF SYNC
- DAMAGED TONE WHEEL/FLEX PLATE (CRANKSHAFT)
- DAMAGED TONE WHEEL/PULSE RING (CAMSHAFT)
- IRREGULAR LAB SCOPE PATTERN OF CMP SIGNAL
- INTERMITTENT CKP SIGNAL LOSS WHEN WIRING IS WIGGLED
- IRREGULAR LAB SCOPE PATTERN OF CKP SIGNAL
-WIRING HARNESS INTERMITTENT
- INTERMITTENT CMP SIGNAL LOSS WHEN WIRING IS WIGGLED
- CRANKSHAFT POSITION SENSOR CONNECTOR/WIRING
- FAULTY CRANKSHAFT POSITION SENSOR

Potential Fixes:
Fix #1:
Inspect your wire harnesses for damaged wires, chafed insulation, or failed wire splices. Use a volts/ohms multi-meter to check the resistance of the ground wire circuits from each sensor. Replace corroded ground wires/connectors and clean ground wire connection points.
Fix #2:
Timing may off. Re-index the distributor/cam sensor per the FSM instructions, or replace faulty distributor/cam sensor pickup module.

Read this >>> http://www.jeepforum.com/forum/f19/j...e-fix-3487474/

A mis-indexed distributor/cam sensor may exhibit surging, light bucking or intermittent engine misfiring. This will most likely occur when the vehicle is at operating temperature and under a light load at approximately 2,000 rpm. The proper indexing procedure must be used as outlined in the service manual.
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  #7  
Old September 14th, 2018, 17:45
deproson deproson is offline
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Loss of cam or crank sensors

Iíll check some of this stuff out over the weekend. Thanks for the info.


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