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Mr Matt 03-18-2013 04:01 PM

A bad new CPS

I hope someone here can help with this, no mechanic has yet done so. Story is, a while ago, my 6 cylinder, 1996 grand jeep cherokee( Laredo) started bucking slightly, perodically. It eventually got worse to the point it stalled. The crankshaft position sensor was determined to be bad, it threw the code out for this.

Mechanic replaced it using an aftermarket item. Car ran ok, and soon a very slight noticeable shudder would occur as the engine was about warmed up. This tremor is now a strong shudder that usually comes on right before the engine is completely warmed up, lasts about 15 seconds, then all is fine.

You can pretty much drive it around the rest of the day ,even leaving the car off for a few hours but will not do it again, unless completely cooled down.

The only codes it throws now are cylinders misfiring- which is a secondary issue - something is giving the engine wrong information.

I am thinking the new aftermarket sensor, about 3 months old is partly bad or something, but is not giving off codes...

Have taken the jeep to 3 mechanics, one of them the jeep dealer, thinking they have seen everything, but so far this has them stumped.

Not sure if anyone else had this issue, again... hope you can help!



Jeeper79 03-18-2013 06:06 PM

Re: A bad new CPS
Only possibility I can think of is an ignition coil. Have seen quite a few coils start to make the engine buck after it is warmed up. Usually runs great until the engine heats up and the coil actually heats up and opens internally.
Just an option

Mr Matt 03-19-2013 04:41 PM

Re: A bad new CPS
Thanks for taking the time to respond, I greatly appreciate it.

At one point I did think it was the coil, I removed it and measure the resistance of the windings... they were within spec.s so I thought that was not it... but maybe it sitll could be? Do you think it is possible?. By the way, at the time I bought a new coil just in case from NAPA, and the windings of the new coil were out of spec to what was in my jeep manual.....

I also replaced the TPS and that did not help....:mad:



Frango100 03-19-2013 10:23 PM

Re: A bad new CPS
Aftermarket crank and cam sensors can give sometimes strange behaviour. Best is to stay with original sensors, to prevent surprises lateron. These sensors not always give a code when they donīt work properly.

Mr Matt 03-20-2013 06:39 PM

Re: A bad new CPS
Thanks, that is beginning to be my conclusion..........

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