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Old 03-21-2012, 03:33 AM   #1
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Idle and RPM unstable

Hi guys, have a 05 wrangler 4.0 auto. Some time after driving for a while my rpm would jump up and down constantly and when that happen if I put it in park it jump even higher. After I shut the engine off and turn it back on the problem go away for that day. Any ideas? I did clean the IAC and the throttle body already. But doesn't seems to fix the problem. Please help.

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Old 03-21-2012, 03:36 AM   #2
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Sounds like Throttle Position Sensor..common. Any engine codes? Notice decrease in MPG yet?

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Old 03-21-2012, 03:37 AM   #3
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Try unplugging your upstream o2 sensors, your computer will revert back to its default fuel map.. (ignore the check engine lights) drive it like that for a day and see if the problem persists. If it does, i'd also look at testing your throttle position sensor, or check for vacuum leaks.
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Old 03-21-2012, 04:22 AM   #4
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No engine code yet. It does eat a lot of gas when that happening. Cuz I notice the fuel gauge drop when I drive in that situation. How can I check for vacuum leak? Also how to test throttle position sensor? Sorry I'm a rookie.
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Old 03-21-2012, 08:30 AM   #5
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X2 but 4.0L 5spd. But the rpm drops from 800-850 to 200-250 and I get very harsh prestall shakes and rattles. Inbetween shifts it sky rockets to just under 3k rpm but when breaking drops to the 200's. I have the engine light on but it reads tps high voltage. Tps low voltage.... Opinions?? Sorry for hijacking post. Seemed relevant
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Old 03-21-2012, 01:38 PM   #6
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Replace the throttle position sensor
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Old 03-21-2012, 01:46 PM   #7
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I just went through a similar thing with my 05 Rubi. It was solved by a thorough cleaning of the throttle body using a can of CRC throttle body cleaner.
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Old 03-21-2012, 02:54 PM   #8
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5 bucks says it's the TPS as mentioned. Happened on my TJ and my Dad's 04 CG limited. Also after doing the cleaning it took a bit of running for the stumbles to work their way out. Just my experience.
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Old 03-21-2012, 03:01 PM   #9
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The TPS isn't something that can be cleaned.. It works like a volume knob on a stereo.. Essentially it just sends the resistance to the ecu.. Which knows where the throttle is based on that resistance.. If there are dead spots it will act funny.. Nothing cleaning will fix.
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Old 03-21-2012, 06:04 PM   #10
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Quote:
Originally Posted by darkproximity View Post
The TPS isn't something that can be cleaned.. It works like a volume knob on a stereo.. Essentially it just sends the resistance to the ecu.. Which knows where the throttle is based on that resistance.. If there are dead spots it will act funny.. Nothing cleaning will fix.

Indeed.
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Old 03-21-2012, 11:00 PM   #11
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Found it. It is the tps. I'm kind of surprise to see a tps gone bad on a 20k mileage jeep. What could have possibly cause this? I'm just trying to get the knowledge so I can avoid it in the future.
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Old 03-22-2012, 09:39 AM   #12
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Tba k you ill try it out soon
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Old 03-22-2012, 10:58 AM   #13
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Originally Posted by blackhawk_TJ View Post
Tba k you ill try it out soon
Let me know if it works.
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Old 03-22-2012, 03:58 PM   #14
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After reading my post I can see how it was misunderstood. I meant that I bet his problem is his TPS. On a completely different note, after doing a thorough throttle body cleaning it is normal to get some stumbles and have a little weird jump here and there until all the cleaner is burned out.
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Old 03-22-2012, 04:41 PM   #15
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Quote:
Originally Posted by BeerMan
After reading my post I can see how it was misunderstood. I meant that I bet his problem is his TPS. On a completely different note, after doing a thorough throttle body cleaning it is normal to get some stumbles and have a little weird jump here and there until all the cleaner is burned out.
I've been doing this everytime o get stummbles

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