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Cary York
Cary York,
Category: Jeep
Satisfied Customers: 207
Experience:  Auto Tech at Certified Auto Repair
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MIL on. swapped plugs, ran one tank with STP treatment,

Customer Question

MIL on. swapped plugs, ran one tank with STP treatment, still on and will run rough when accelerating unless doing so very gradually. computer says #6 cylinder
JA: Do you have the trouble code? Do you have a code reader or scan tool?
Customer: yes computer says #^ cylinder
JA: Great. If you share the code with me, I'll pass it along to the Jeep Mechanic. He'll be able to diagnose your issue much faster with a code. What is the model/year of your Jeep?
Customer: 2100 Grand Cherokee Ltd 5.7 L hemi I think the code was P300
JA: What year is your Grand Cherokee?
Customer: 2011
JA: Are you fixing your Grand Cherokee yourself? What have you tried so far?
Customer: tried replacing the spark plugs, ran STP gas conditioner through it. Did that much on our own. Don't want to get taken at the repairshop.
JA: Anything else you want the mechanic to know before I connect you?
Customer: Other than that the only thing wrong is the back up camera which quit 300 miles after the warranty ran out. The jeep currently has 112,000 miles on it and I have been good about maintenance, oil changes etc..
Submitted: 9 months ago.
Category: Jeep
Expert:  Cary York replied 9 months ago.

Hi, I’m Cary and I’ll be helping you today.
Please understand that I can't smell, hear, or touch the vehicle, so patience is appreciated. Before leaving the site make sure and leave me a rating. You can still reply to me as many times as needed, even after the rating..

90% of the time it is the coil. The code is P0306? #6 cyl.? If so with the engine running unplug the #6 coil elec connector. See if it changes the way the engine runs. If not then swap the #6 coil to another cyl. If the problem follows the coil it is the coil.

Expert:  Cary York replied 9 months ago.

When you swap the coils from cyl to cyl. Try unplugging the #6 cyl coil elec connector with a different coil on it. If it makes a difference in the way the engine runs #6 cyl is ok.

Expert:  Cary York replied 9 months ago.

Remember if you rate me we can still continue the discussion.

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