99 PCM replace/update
#76
CF Veteran
I mean, you could have this, too:
https://www.jeepforum.com/forum/f13/...ptoms-1405626/
The center could spin in worse case scenario.
https://www.jeepforum.com/forum/f13/...ptoms-1405626/
The center could spin in worse case scenario.
#79
CF Veteran
Pull the inspection plate on the bell housing and check the condition of the flexplate. Has the P1391 been there since you had everything apart?
#80
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From: CO
Year: 99
Model: Cherokee (XJ)
Engine: 4.0
It started before and exists still. I just had the flex plate off to recheck torque converter bolts, I'll pop it off again anyway and see what can be seen.
#81
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#83
CF Veteran
Allright. I see this is about xj, not zj. ZJ did not have the tcm, as the zj and xj have completely different transmissions. My bad.
#84
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From: CO
Year: 99
Model: Cherokee (XJ)
Engine: 4.0
No sweat,
pulled the pan, front had oil seeping, ugh I detest rework. How much play in a chain is normal, it has some, but nothing crazy I don't think. Bought rosin flux for making the test leads as AWG suggested. Do you think a t pin will except solder?
Didn't get around to pulling the distributor cap and checking the chain degree, it was late and I'm beat tired.
Last edited by 4x4jeepmanthing; 06-22-2019 at 07:23 PM.
#85
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#86
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Year: 96
Model: Cherokee (XJ)
Engine: 4.0
use small safety pins about 1"long
I would really want to eliminate excessive chain slack..that is what the warning code is saying..or an intermitent loss of signal
hopefully ur close
#88
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From: CO
Year: 99
Model: Cherokee (XJ)
Engine: 4.0
Lol,
I tried the donor pcm, that didn't work so I called the shop back that did the diagnostic, they are going to give me my money back. Really nice folks, but he didn't even know where to point me because of how well everything looked. They use a Snap on scope. He was happy to take another look, but he also said he believed he wouldn't find anything new if they did. He would like to know if I figure it out.
Anyhow, 7 degree on the chain. I did this twice to be sure. I need to verify that tolerance.
I tried the donor pcm, that didn't work so I called the shop back that did the diagnostic, they are going to give me my money back. Really nice folks, but he didn't even know where to point me because of how well everything looked. They use a Snap on scope. He was happy to take another look, but he also said he believed he wouldn't find anything new if they did. He would like to know if I figure it out.
Anyhow, 7 degree on the chain. I did this twice to be sure. I need to verify that tolerance.
#89
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Joined: Mar 2016
Posts: 3,551
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Year: 96
Model: Cherokee (XJ)
Engine: 4.0
I tried the donor pcm, that didn't work so I called the shop back that did the diagnostic, they are going to give me my money back. Really nice folks, but he didn't even know where to point me because of how well everything looked. They use a Snap on scope. He was happy to take another look, but he also said he believed he wouldn't find anything new if they did. He would like to know if I figure it out.
Anyhow, 7 degree on the chain. I did this twice to be sure. I need to verify that tolerance.
Anyhow, 7 degree on the chain. I did this twice to be sure. I need to verify that tolerance.
7 degrees, did you say earlier that was right on the max ?...is that 7* of slack ?
I dont have much experience with chains wearing & stretching, but it does happen on engines with high mileage, set a code on models with electronics
there should be be other people that know all about Jeep timing chains, the XJ has a pretty robust looking arrangement..the GM Alloytec not so much
#90
CF Veteran
So from what I can gather, the P1391 has occurred on 2 entirely different engines (except for the flexplate)? You put new sensors on the old engine, but reused them on the new engine? What year is the replacement engine?