1987 cherokee issuse
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Joined: Aug 2011
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From: Prescott, Az
Year: 1990
Model: Cherokee (XJ)
Engine: 4.0
....Ah...Cruiser, now I get it. Wallowing the holes lets you move it DOWN to be closer. Couldn't figure how larger holes would make it closer IN. So the downward pressure there is crucial. THANKS!(again).[/QUOTE]
Correct. The closer it is to the flywheel, the stronger the signal it generates.
I think one of the biggest problems with the aftermarket parts is that the sensor is molded too deeply into the plastic on the CPS and it's too far from the flywheel. Hence, people replace their CPS, don't test the output, ASSume it's good, and chase their tails looking for other causes of their problems when in fact they just installed a POS CPS.
Hmmmm. POSCPS has a ring to it, doesn't it?
Correct. The closer it is to the flywheel, the stronger the signal it generates.
I think one of the biggest problems with the aftermarket parts is that the sensor is molded too deeply into the plastic on the CPS and it's too far from the flywheel. Hence, people replace their CPS, don't test the output, ASSume it's good, and chase their tails looking for other causes of their problems when in fact they just installed a POS CPS.
Hmmmm. POSCPS has a ring to it, doesn't it?
Thread Starter
Junior Member
Joined: Sep 2011
Posts: 36
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Year: 1987
Model: Cherokee
Engine: 4.0
so without even testing the CPS im 99% sure thats what it is. i was talking to a certified jeep tech thats a friend of mine and he said on the older ones like mine if you clean the motor dont plan on driving for a day or two.... he said degreaser water and oil love to **** with the CPS.... thanks guys i appreciate all the help!!!!!!
::CF Moderator::
Joined: Aug 2011
Posts: 43,971
Likes: 1,578
From: Prescott, Az
Year: 1990
Model: Cherokee (XJ)
Engine: 4.0
so without even testing the CPS im 99% sure thats what it is. i was talking to a certified jeep tech thats a friend of mine and he said on the older ones like mine if you clean the motor dont plan on driving for a day or two.... he said degreaser water and oil love to **** with the CPS.... thanks guys i appreciate all the help!!!!!!
We degreased/cleaned engine bays on hundreds of 4.0 Jeeps and had no issues with the CPS.
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Junior Member
Joined: Sep 2011
Posts: 36
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Year: 1987
Model: Cherokee
Engine: 4.0
hmm... if the TPS was ruined my problem wouldnt happen (like it did that one day) and go away.... im thinking its a the CPS.... and what i was trying to say in a hurry earlier is his own word when you pressure wash them they go threw sensors like no other... he also had said just getting them wet can mess with them a little bit.
CF Veteran
Joined: Mar 2010
Posts: 47,923
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From: Broward County Fl.
Year: 1989 xj sport 2dr
Model: Cherokee
Engine: 12 hole bosch Injectors
so without even testing the CPS im 99% sure thats what it is. i was talking to a certified jeep tech thats a friend of mine and he said on the older ones like mine if you clean the motor dont plan on driving for a day or two.... he said degreaser water and oil love to **** with the CPS.... thanks guys i appreciate all the help!!!!!!
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Joined: Aug 2011
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From: Prescott, Az
Year: 1990
Model: Cherokee (XJ)
Engine: 4.0
Test it for AC voltage output, not the ohms resistance test. What COULD have happened is you got the connector for the CPS wet. They're sometimes a source of excessive resistance anyway. That's why when people have a crank-no start condidtion they can unplug that connector and plug it back in and the Jeep fires right up.
CF Veteran
Joined: Aug 2011
Posts: 10,489
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From: Nor-Cal Coast
Year: 90,84
Model: Cherokee
Engine: 4.0,2.5
That happened enough on one that I painted the connector white so my mom could point at it, "my son says to try unplugging that one and putting it back"
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Joined: Jun 2011
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From: Nor-Cal
Year: 1990
Model: Cherokee
Engine: The venerable 4.0
Originally Posted by DFlintstone
That happened enough on one that I painted the connector white so my mom could point at it, "my son says to try unplugging that one and putting it back"
CF Veteran
Joined: Aug 2011
Posts: 10,489
Likes: 24
From: Nor-Cal Coast
Year: 90,84
Model: Cherokee
Engine: 4.0,2.5
Yea, with caution. Blasting grime into the wrong place--not good. And yea, I've seen some of your pics, your stuff is clean enough to clean! I'll take two power washers thank you.
Thread Starter
Junior Member
Joined: Sep 2011
Posts: 36
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Year: 1987
Model: Cherokee
Engine: 4.0
fuel pump took a dump on me so.... im taking a wild guess at this but thats probably why iv had all these problems and figured out the damn pcv valves that i broke on accident is why gay and oil are mixing.... whohoo go me!!!! NOT!!! fuel pump will be here tomarrow...
Are the injectors brand new? I put in some reconditioned ones that worked for a while, then I had similar issues, poor gas mileage, sputtering, staling. Ended up putting originals back in and all was good. I had a bad injector that was dumping too much gas in. It was more pronounced when the engine was warm, hard starting was another symptom.
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Tj Cope
Stock XJ Cherokee Tech. All XJ Non-modified/stock questions go here
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