Temperature dependent cam sensor issues

ndaddy

Member
Joined
Jul 7, 2020
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45
Location
Maryland
This Jeep has been a disaster!! The just empty everyone’s pockets has epitomized my six months as a TJ owner

my issue now is whenever it is cold out (<55 degrees about) or very hot, the car has to crank for about 12 seconds before it turns on. It throws a p0340 code every time (camshaft position sensor error), and when that happens, it won’t drive over 2400rpm without cutting out. I don’t drive too fast, especially now r/t that issue.
As soon as it is nicer or warmer out, the car starts no problem and the CEL will even clear itself until the weather drops again.

I am on my fourth CAM sensor and they all have the same issue. I read that the after market sensors are trash, but of course my car was bought without the original sensor. And they’re discontinued and unavailable across the US per the Jeep parts department.

what do I do at this point? Spacer? Can it be related to oil pump ?

Sell on a nice day ? Very strange that is weather temperature dependent but I’m at a loss here
 
follow up for anyone down the line who comes across this. allegedly a common issue with aftermarket sensors. so my advice first is to keep your OEM camshaft position sensor!!! it is 100% the camshaft position sensor causing the issue. When the temperature is warm, car works with no issues at all. When it is cold, it cranks for a long time before starting and also will not pass 2400rpm (while engine is cold; but if i reset car after 10 minute drive, it will start no problem and drive past 2400rpm).

To confirm the weather relation to CAM issue, I did a test. I tried starting the car with the cold current sensor (45 degrees outside)- took very long to start; had issue with RPMs as previously mentioned). Turned off car, waited two hours.


Tried to start car again to ensure "long start". At this time, I disconnected the current CAM sensor and installed a previously used sensor that has been sitting in my house room temperature. This previous sensor had identical issues when used in the past. Now that the temperature was warm, the car started with ZERO issues and drove with ZERO issues. I am sure it will resume the CEL and issues once the metal reaches outside temperature.

That being said - any advice? I guess i could theoretically switch back and forth between sensors when i want to drive, but changing the cam does take a few minutes. Anyone find use of a quick release bolt of somehow to allow rapid change of camshaft?
otherwise, any advise short of changing the sensor any time i feel like driving in cold?
 
just thinking out loud, it would be interesting to know if this was related to changing resistance to the sensor internals or changes in sensor clearance due to temperature related expansion and contraction, the latter could possibly be addressed? Almost 50 years ago I worked as a test tech and did a lot of component sorting and classification of resistors based on the changes in resistance in controlled temperature liquid immersion for the aerospace industry with a wide variance of values from one resistor to another. I‘ve got one of the Amazon cheep Chinese knock off ones arriving Thursday and a New Crown sensor from my last OPDA, when I get the Chinese Mopar I’ll pull the factory unit and measure the clearance with a digital caliper hopefully it is sensative enough to the measure any difference between the 3?
 
If the issue is clearance related perhaps positioning the sensor pick up closer to the sending source might work, I notice my old factory sensor shows sign of scuffing on the face of the pick-up possibly from contact with the OPDA as the bushing developed play the aftermarket could have been made with wider tolerances between the pick-up and sender.

if it is temperature related resistance affecting initial startup preheating the sensor much as you’d warm a diesel truck engine might work.
 
If the issue is clearance related perhaps positioning the sensor pick up closer to the sending source might work, I notice my old factory sensor shows sign of scuffing on the face of the pick-up possibly from contact with the OPDA as the bushing developed play the aftermarket could have been made with wider tolerances between the pick-up and sender.

if it is temperature related resistance affecting initial startup preheating the sensor much as you’d warm a diesel truck engine might work.
keep me updated! definitely makes senses as cold "shrinks". i guess you can get it a little closer by grinding it down some?
 
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Looking on Amazon I was thinking if in the extreme case I couldn’t find a working replacement CPS, something fashioned from parts like these and a dash mounted switch would make a workaround? Obviously not a first choice but we’re talking keeping the Jeep on the road and switching it out for a warm one in the house sounds like a hassle.
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Of course that won’t help for the very hot condition.
I agree that it would be an extreme hassle unless you barely drive. not sure how it would work since the CAM in the cold will always shrink a bit though and not work.

I purchased and installed the Echlin CPS from NAPA today referred from @ABQWrangler and a second user who had luck. fingers are crossed.
 
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Hope it works, I’m currently running a Napa MAP since it was first to arrive and no issues so far.