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AZTechBrian, ASE Certified Technician
Category: Jeep
Satisfied Customers: 669
Experience:  Owner
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2003 jeep grand cherokee --- engine runs fine sitting still,

Customer Question

2003 jeep grand cherokee --- engine runs fine sitting still, boots down when trying to accelerate when moving, has dtc po108, and shows that all cylinders are misfiring . Runs fine sitting still, checked for vacuum leaks, replaced plugs, air cleaner, coolant temp sensor
Submitted: 7 months ago.
Category: Jeep
Expert:  AZTechBrian replied 7 months ago.

Hello. Is P0108 the only DTC?

Customer: replied 7 months ago.
The scanner shows misfire codes for all cyclinders
Expert:  AZTechBrian replied 7 months ago.

The P0108 is a MAP sensor code. The map malfunction is likely the cause of the random multiple misfire condition. Have you done anything with the map sensor?

Customer: replied 7 months ago.
Nothing done with the map sensor
Expert:  AZTechBrian replied 7 months ago.

OK. Please take a look at the map sensor. Make sure there are no obvious problems with it. If you would like, I can email you the step by step diagnostic procedure for the map code in a PDF for 5.00. Usually it will be the result of a failed sensor.

Expert:  AZTechBrian replied 7 months ago.

Would you like a copy of the diagnostic instructions for the map code?

Customer: replied 7 months ago.
replaced sensor, no change. scanned vehicle again, now have a new code of po353. vehicle acts like catalytic converter is clogged, owner had cat replaced. like I said it runs fine sitting still , but when attempting to accelerate when taking off, it seriously boggs down and sometimes makes a popping sound. it will eventually pick up speed if you ease off the accelerator . working on vehicle between other jobs.
Expert:  AZTechBrian replied 7 months ago.

Ok, so you replaced the map and that code is gone but now there is a new code? The P0353 is a cylinder 3 misfire indicating a problem with the primary circuit. That could be from a damaged wire to the coil, A bad coil itself, etc Look over the coil and the wiring. Look for any signs of loose connections, damaged or melting wiring.

Expert:  AZTechBrian replied 7 months ago.

How did it all look?

Customer: replied 7 months ago.
Everything looked fine at the coil, could that coil cause it to feel like a total loss of ability to accelerate. It acts like vehicle in the old days would react if the were out of time. Tried moving the camshaft sensor, helped some. Put everything back to where I found it. Have a coil in the shop, will.try that
Expert:  AZTechBrian replied 7 months ago.

Ok. Try swapping the coil with the other one you have and also check for possible damaged wiring else where in the engine compartment, like near the rear of the cylinder head, etc.