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magradze 04-07-2010 08:05 AM

Jumping RPM in 2003 WJ
I got problem with RPM in my WJ Laredo 2003, 4L i6.
When I drive 50-60 mph with approx 2000 rpm, rpm starts to "wobble", feels like it rapidly switches between high and lower gears.
When I turn overdrive off or accelerate to up to 3000 rpm problem is gone.
No check engine light is on. I checked transmission oil level/quality and it's ok.
Is problem in tranny or engine? What to do?

B T C 04-07-2010 11:28 AM

Re: Jumping RPM in 2003 WJ
Does it also do this when cruise control is engaged? If it were a 4.7L, I would say the throttle position sensor is bad. I guess that could also be the case on the 4.0.

magradze 04-07-2010 11:32 AM

Re: Jumping RPM in 2003 WJ
I rarely use cruise control. I'll try it. What if it does?
Should the Check Engine light indicate this defect?

B T C 04-07-2010 11:40 AM

Re: Jumping RPM in 2003 WJ
The check engine light never came on when my TPS was bad. In my case, it seemed much more noticeable when cruise control was engaged, but the symptoms were pretty much identical to what you're describing. I'm not real familiar with the 4.0. The TPS for the 4.7's is fairly cheap, and supposedly pretty simple to install. If the sensor for the 4.0 is cheap, you could always buy one, install it and see what happens. The worst case scenario would be that you have a new TPS that you don't really need.

magradze 07-03-2010 04:25 PM

Re: Jumping RPM in 2003 WJ
It was TPC.
problem is gone... so far.

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