Technical help, 2004 Grand Cherokee

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nothingbutdarts

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The daughter called last night and said her 2004 Grand Cherokee 4.0l will only start and keep running at around 2,000 RPM. If she lets off the throttle it just dies. It will do this everytime you go to start it, it just doesn't want to idle. I'm going tonight after work to look at it, just looking for some ideas as to where to start. I don't have a scanner. I was thinking something like the throttle position sensor or the air idle solenoid???

Thank You in advance for any ideas!!!
 
turn the ign. key on and off 3 times quickly, with the 3rd time leaving it in the run position. See if the odometer comes up with a code, or codes, and write it down. when its finished it will say "done" I know this works on an 01 gran cherokee, and I think later ones as well. Once you have the code you can go online and find troubleshooting websites that will tell what is wrong. I'v done this several times on my wifes jeep, for the stupid fan relay that likes to go bad. Actually I have all the codes if you cant find them online.
 
AIS Motor. Very likely clogged with carbon. The carbon forces the AIS motor into an open position. Until the car warms, it will stall. Unless the check engine light is on, there will be no code to check.
I would also look for a vacuum leak. But the AIS being filthy is the usual suspect. Some brake cleaner and a toothbrush and your all set. While you're there scrub out the throttle body.
 

Not enough info to even begin to diagnose. Anybody throwing anything out is just guessing. I would need to see some data, like fuel trim, O2 sensor voltage, crank and cam signals, probably fuel pressure. Start with codes - there should be some hard codes if it runs that poorly. They are the compass that points you in the right direction. I believe the key on, key off works for a 2004 but am no longer sure where to cross the two digit codes. I'm sure a little google searching will find them. All I remember for sure is 55 means it is done.
 
Thanks all for the input!!! Did the key on/off and there are no codes. I believe the battery is toast and voltage is so low it is messing up the computer when it's starts.

I'll let you all know.
 
nothingbutdarts said:
Thanks all for the input!!! Did the key on/off and there are no codes. I believe the battery is toast and voltage is so low it is messing up the computer when it's starts.

I'll let you all know.
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When my grandma's did this, the tow truck came out and jumped it and ran it over 2000 for a couple of minutes. The computer got reset and you have to run it "manually" by foot for a couple of minutes and then it worked fine. You have to run it for a few minutes to reprogram the computer is what the tow truck driver said.
 
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