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Brad
Brad, Jeep Dealership Tech
Category: Jeep
Satisfied Customers: 6955
Experience:  19 Yrs Chrysler/Dodge/Jeep. ASE Master (L-1) Certified
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P300 codes 301grand Cherokee

Customer Question

P300 codes 301(###) ###-####grand Cherokee
Submitted: 10 months ago.
Category: Jeep
Expert:  Brad replied 10 months ago.

Good afternoon and welcome to JustAnswer!!

What is the compression for all cylinders? Also what is the fuel psi and when did this start?

Talk soon,

Brad

Customer: replied 10 months ago.
Fuel pressure is 44 psi with key on and 50 psi with car running. While car is running needle shakes a little. Did not check compression
Expert:  Brad replied 10 months ago.

Can you check the compression so we can make sure the base engine is ok.. Also if you erase all the codes and start it do all the codes come back active?

Customer: replied 10 months ago.
150 psi in all cylinders the codes clear and will come back on after 10 miles or sometimes longer been going on for a few months
Expert:  Brad replied 10 months ago.

If the misfires codes clear and it's an intermittent issue then it sounds like carbon on the valves.. Can you decarbon the valves following the PDF I attached to see if it resolves your issues? Because it sounds like your base engine is ok and if it were a spark plug or injector then it would misfire all the time..

I hope this helps,

Brad

Customer: replied 10 months ago.
Don't understand what # ***** is. How can I get carbon of valves
Expert:  Brad replied 10 months ago.

What are you referring to a #39? It basically says to spray decarbon into the breather and allow it to soak 2-3 hrs and then drive it in low to keep the RPM"S up to flush out all the additive and see if your issues are still present..

Expert:  Brad replied 10 months ago.

I see this question is still open.. If you need more assistance feel free to reply, and if not then don't forget to rate so I'm compensated for my time..

Have a greatday,

Brad

Expert:  Brad replied 10 months ago.

If you need more assistance feel free to reply and if your all set I would greatly appreciate a positive rating so I'm compensated for my time..

Have a great weekend,

Brad

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