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2000 xj won't run

tom tom

NAXJA Forum User
Location
Monroe,MI
Ok this is what I did . I replaced the flexplate on the wifes 2000 xj. The new one matched up with the old . Fired it up after I was done and the engine chugs and won't stay running , my first thought was the cps and changed that out but there was no change. It sounds like a timing issue but it has the coil pack. This is a 2000 xj with a 4.0 and auto trans .Anyone have any ideas that would help Thanks
 
After the battery is disconnected, they do run pretty rough for a few minutes. Assuming you are beyond all that, you could try timing the cam position sensor. Have you seen the "toothpick" method?

Why did you have to do the flexplate?
 
had to change the flexplate for it cracked . Just don't understand what changing the flexplate has to do with how it runs. I found the toothpick method last night and tried it this morning everything lined up like it should. The latest is it won't start and sounds like timing but cann't find anything on timing it
 
1. Flexplate/flywheel has "notches" big and small. As they pass the CPS/CKP crank sensor it generates a signal, either "big" or "small" to the ECU/PCM, which counts the signals and then adjusts ITS firing of the ignition based on that and other data from other sensors.

So, if the air gap is too large between the CPS/CKP and the "notches" on the flex/fly, that will screw with how the engine runs. If the CPS/CKP is out of specs, that will screw with how the engine runs--if it runs at all.

Question: where did you source the replacement flexplate? Is it the correct one?
 
I have been helping him with it. Order the flexplate on line. The thing is when it was first put back together with the new flexplate. It ran fine. after a few mins of running it started to mis. Took it for a drive and it stalled on him. He manged to get it back home and now will not start. Sounds like timing. Can smell gas, but just not catching.
 
i don't recall what mounting style cps is on a '00, but on some later 4.0's, the notch-to-cps air gap is VERY important. there's actually a little paper spacer(about .060, i think) that sticks on the end of the sensor and gets pressed up against the flexplate/flywheel. upon starting, the paper gets knocked off the cps. i've seen an out of spec gap either destroy the end of the sensor, and/or cause the engine to run like total crap.
 
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