Can't figure it out...

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12-11-2018, 10:26 AM

#16

Friar Mountain XJ

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Join Date: Dec 2018

Location: Virginia

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Year: 1998

Model: Cherokee (XJ)

Engine: 4.0

Quote:

Originally Posted by dave1123

I would suggest nothing works without a CPS signal. The PCM won't turn on the ASD relay without a signal from the crank sensor. The ASD relay controls both the ignition and the injector circuits. It won't turn on the fuel pump as well without that signal except for that initial fuel rail charge when you first turn on the key. It's true the cam sensor tells the PCM which injector to activate, but the crank sensor tells it WHEN to activate the injectors and fire the plugs.

The last two times I've driven it I could drive it 13 miles. It's runs perfect then it shuts off and won't fire up until cold. I know it has nothing to do with 13 miles but that's how it happened. I left the house to get my new KO2's mounted up and pulled into the gas station beside the tire shop and it shut off. It cooled and I drove home. It shut off as I stopped. Replaced the coil and went back to get the tires mounted. It did it again as soon as I got to the tire shop. Had to let three people go ahead of me while it cooled. With tires mounted I drove home and it shut off as I came to a stop. I guess that makes 4X13 miles.😀

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12-11-2018, 12:41 PM

#17

dave1123

Old fart with a wrench

Join Date: Nov 2010

Location: Manlius, east of Syracuse, NY

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Year: 2000 XJ Sport & WJ Laredo

Model: Grand Cherokee (WJ)

Engine: 4.0L

All I can say for sure is when the CPS starts to fail, it can shut down the engine just like you turned off the key, whenever it decides to. Mine would die, then sometimes start right back up when I tried it. Sometimes it had to cool for awhile. A couple of times it started itself back up because the crank was still turning! Really screwy.

Last edited by dave1123; 12-11-2018 at 12:43 PM.

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12-13-2018, 12:35 PM

#18

97grand4.0

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Location: syracuse ny

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Year: 1997

Model: Grand Cherokee (ZJ)

Engine: 4.0, new lifters valve job with new springs and exhaust valves, preload set with shims

Usually the crank sensor will throw a code but that cam sensor is a dilly it can be bad for weeks before sending a code. worse yet is installing anything but a Mopar because it will work for 4 days then start up again.