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Mark, 22 Year Factory trained technician
Category: Jeep
Satisfied Customers: 11332
Experience:  Jeep factory training........25 years in the industry.
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1998 jeep grand cherokee: DEAD battery..Drove it for a bit..restarted

Resolved Question:

My 1998 jeep grand cherokee 4.0 had a DEAD battery and sat for several days. After jump starting, the engine will NOT idle below 2000 rpms. Drove it for a bit, restarted, nothing works. Any suggestions?
Submitted: 8 years ago.
Category: Jeep
Expert:  Mark replied 8 years ago.

-Could you explain your situation a little more?


Drove it for a bit and nothing works??

Customer: replied 8 years ago.
I apologize for the vagueness, by nothing works, I mean that the idle speed won't reduce to a reasonable level.
Expert:  Mark replied 8 years ago.

Generally speaking, if the idle control motor cannot control the idle speed, then there is some excess air entering the a vacuum leak.


Maybe have a look and make sure that there aren't any vacuum hoses that got knocked off.


If you don't see a vacuum leak, then your idle motor maybe be caked up in carbon and crud, preventing it from moving freely.


In this case I would suggest a thorough cleaning of the throttle body and idle motor.........which is attached to the side......using an old toothbrush and a can of carb cleaner.


Worse case scenario, you may need to replace the idle motor.


Just a few thoughts for you.....

Mark and 5 other Jeep Specialists are ready to help you
Customer: replied 8 years ago.
Nothing related to the loss of battery that can be affecting the idle?
Expert:  Mark replied 8 years ago.

Normally, a dead battery has the opposite effect........the engine doesn't want to idle unless you keep your foot on the pedal until the PCM relearns how to idle the engine.


Any chance you jumped this backwards....or anything like that?

Customer: replied 8 years ago.

Everything went well on the jump start, fairly certain I connected correctly. What would I see had I not?

Expert:  Mark replied 8 years ago.

You would have had sparks..........I was just wondering if there was a chance of engine computer damage from jumping backwards.


So, if that is ok, I would go back to my previous suggestion.