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Old May 25th, 2013, 08:04 AM   #1
Catnip 0_o
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Default Crank position sensor not setting properly

02 auto TJ 4.0

Long story short, my CPS failed me last July and I bought an aftermarket one. Since then I will get misfire and lag at random times, usually at 2800+rpms or hill inclines. I did some research and found that aftermarket CPS can cause this so I went to the dealer and got a MOPAR one. Well when I went to pull the old one out I noticed the little paper spacer was still on it, you know the ones that's supposed to get sheared off after first startup...

Anyways, I installed the new one and first start this morning I took a lot of cranks to start, I'm wondering if it isn't set properly, anyone else have this problem? How do I go about adjusting it, not much room to work with..

Thanks

Last edited by Catnip 0_o; May 25th, 2013 at 08:33 AM.
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Old May 25th, 2013, 08:15 AM   #2
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How many miles ? From what your saying I am leaning toward a fuel pressure. Like a fuel filter, or Fuel pump not keeping up.
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Old May 25th, 2013, 08:32 AM   #3
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How many miles ? From what your saying I am leaning toward a fuel pressure. Like a fuel filter, or Fuel pump not keeping up.
Already replaced the TPS, cleaned throttle, IAC, Cam Sensor, Fuel Pump w Regulator (spectra premium), plugs, Ignotion coil, I am certain it is the CPS. Before I replaced it with the mopar unit yesterday it would start right up but when the motor got hot would randomly misfire. Your CPS can undergo thermal failure. Now with the new and better CPS installed, it has longer crank time. Should I just pull the spacer off and install it?

Oh and 145k miles
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Old May 25th, 2013, 11:25 AM   #4
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Anyone??
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Old May 26th, 2013, 05:55 AM   #5
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I was told by a jeep dealer tech to replace the cam & cps sensors as a pair so they relearn properly.
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Old May 26th, 2013, 05:57 PM   #6
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pull the cps, look at the cam gear. the cps units that fail, often take out the cam gear.
turn the engine over to top dead center. and set to zero at the timing marks.
take the top cover off the cps unit, it should have an alignment pin hole in it.
find a nail or punch that fits it tightly. drop it in at the point. it will tolerate up to 7 or 8 degrees off.
it will run better the closer it to zero is. the dealer can sync it if you cant get it right.
if you can get it within a couple degrees of zero it will run fine.

your jeep is a 2002, mine is an 05, they have different cps units.
im assuming your install procedure is similar.

Last edited by joe_jeep; May 26th, 2013 at 06:02 PM.
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Old May 28th, 2013, 09:50 PM   #7
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Quote:
Originally Posted by joe_jeep View Post
pull the cps, look at the cam gear. the cps units that fail, often take out the cam gear.
turn the engine over to top dead center. and set to zero at the timing marks.
take the top cover off the cps unit, it should have an alignment pin hole in it.
find a nail or punch that fits it tightly. drop it in at the point. it will tolerate up to 7 or 8 degrees off.
it will run better the closer it to zero is. the dealer can sync it if you cant get it right.
if you can get it within a couple degrees of zero it will run fine.

your jeep is a 2002, mine is an 05, they have different cps units.
im assuming your install procedure is similar.
I'm afraid I'm really confused about everything you just said :p
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Old May 29th, 2013, 12:52 AM   #8
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i was assuming you meant cam position sensor, cause they commonly fail, sorry.

when you are gonna start it. turn the key forward to the run position for 5 seconds, then start it.
jeeps do have issues with the drain back valve in the fuel system. takes a few seconds to prime the system again.
all the fuel leaves the fuel rail and drains back to the tank. if thats the issue it will start very quickly after the rail is pressurized again.
my old tj did that. give that a try.

Last edited by joe_jeep; May 29th, 2013 at 01:01 AM.
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Old May 30th, 2013, 06:42 PM   #9
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Quote:
Originally Posted by joe_jeep View Post
i was assuming you meant cam position sensor, cause they commonly fail, sorry.

when you are gonna start it. turn the key forward to the run position for 5 seconds, then start it.
jeeps do have issues with the drain back valve in the fuel system. takes a few seconds to prime the system again.
all the fuel leaves the fuel rail and drains back to the tank. if thats the issue it will start very quickly after the rail is pressurized again.
my old tj did that. give that a try.
haha yes a misunderstanding xD

for the first few days after replacing the crank sensor with the MOPAR one it would have the longer crank and occasionally sputter after start for a few seconds but i noticed last night and today it is starting to fix itself. Only cranks about 2 times before it starts and the sputter is going away :) hopefully my misfire on highway speeds is completely gone!
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Old May 30th, 2013, 06:49 PM   #10
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cool!
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