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Chris (aka-Moose)
Chris (aka-Moose), Technician
Category: Jeep
Satisfied Customers: 48357
Experience:  16 years of experience
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Going down the road the engine will quit then run as if you

Customer Question

Going down the road the engine will quit then run as if you turn off the ignition and then back on quickly, like one second. The ignition switch has been replaced due to recall. I'm the third owner and just got this vehicle in June.
JA: Has the car been stalling out?
Customer: Not yet. It has only done this at speeds of 40mph or more.
JA: What is the model/year of your Jeep?
Customer: 2007 Grand Cherokee 5.7L
JA: Are you fixing your Grand Cherokee yourself? What have you tried so far?
Customer: yes. Checked codes, none. checked to see if plug is loose on back of ignition switch.
JA: Anything else you want the mechanic to know before I connect you?
Customer: I have a severe vibration, also intermittent, when I take it out on the interstate and get up to 70 mph it will start a vibration that's exactly like running over the rumble strips on the side of the road. It continues when I coast and put the trans in neutral. I have checked drive shafts and all seem tight. I may go a week or two with no problem then take it out and it will start the vibration after I drive at 70 mph for 3-4 miles.
Submitted: 8 months ago.
Category: Jeep
Expert:  Chris (aka-Moose) replied 8 months ago.

Welcome, I'm Chris (aka Moose), my normal schedule online is around lunch and after dinner till early morning.

We are permitted to help address one concern per question. Which issue do you want to tackle on this question?

Customer: replied 8 months ago.
I found the answer to the vibration problem on another forum. The engine cutting out is disturbing and seems to be related to the ignition switch. Have you seen a common cause? Crankshaft sensor would give a code, right? My '94 Dodge Van did the same thing and it was the crank sensor....also very intermittent.
Expert:  Chris (aka-Moose) replied 8 months ago.

How long is the engine off when this occurs and due you have to restart it?

Expert:  Chris (aka-Moose) replied 8 months ago.

Hello again Chris here,

  1. I have to assume you were not pleased with my help, because you have not replied or rated the post.
  2. What would you like to do regarding your question now?
  3. Do you still need help? Please reply I want you to get equal to or more than what you paid for.
  4. This post is coming up on the 7 day mark where it times out. That can prevent me from being able to post answers to your replies.

Thanks Chris

Customer: replied 8 months ago.
I found out the sparks plugs need changing. When the plugs have 30K miles on them the internal resistance changes. The ECU sends a signal to the coil pack and receives feedback from the coil. If it receives anything different than the pre programmed pulse level, it shuts down the engine with no warning or codes. The spark plugs must be replaced with Champion copper #570 with black tipped electrodes not silver. Any other spark plug will return cause intermittent engine shutdown.
Expert:  Chris (aka-Moose) replied 8 months ago.

Glad it is resolved.