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Old March 2nd, 2017, 08:32
58HalfCab 58HalfCab is offline
NAXJA Forum User
Join Date: Aug 2014
Location: Columbia
Posts: 4
P1391 Running Great

I recently finished a 96 XJ build. Stroker build with a 4.2 crank. Not sure what year the block is. At the time of the motor build I also swapped in an AX-15 transmission. I purchased a new 96 flexplate. Timing chain is new. I have built many motors. Took my time, checked all the measurements. Feel good about the build.

The jeep is running great. I put about 400 miles on it, changed the oil, and then drove it from my home in St. Louis to KOH, Moab, and back without any issues. The motor has tons of power and sounds great.

I need to pass an emissions test but have a check engine light on. P1391. Mismatch between the crank position sensor and the cam position sensor. If I erase the code it will stay off until the shortly after the 2nd start regardless if the first start is 1 minute or 1 tank of fuel.

First I replaced the Cam Position Sensor in the distributor with an auto parts store sensor. Didn't fix it. Replaced the Crank Position Sensor with an Auto Parts sensor. Didn't fix it. Got a Crank Position Sensor from the dealership. Didn't fix it.

Next I plan to get the cam sensor from the dealership. Any other ideas? I've got to be missing something here. The timing chain is not stretched. It's running too well for the timing chain to be off. There is no adjustment in the distributor without moving a tooth, which again it's running great.

Thanks for all the help!

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