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-   -   My dads '99 WJ laredo. HELP!!!!!! (http://www.jeepgarage.org/f203/my-dads-99-wj-laredo-help-70409.html)

Tuzmaster 01-14-2014 10:32 PM

My dads '99 WJ laredo. HELP!!!!!!
 
Hey all

We are a Jeep Grand Cherokee family. The problem is with my dads 1999 Jeep Grand Cherokee Laredo. Has a 4.7 V8 with ~222k miles. A few problems.

First, the main, is what I think with a transmission. When she is cold, she starts up and drives fine. It seems like at a certain temperature, when she is at either 3rd or 4th gear, all of a sudden the RPM drop to near idle (does not die) and starts shaking a bit. No matter how far you put in the accelerator, the RPM does not go up. If you park on the side of the road for a bit, then you can drive again for a bit and same thing happens. There are no codes given by the computer.

Second, the transfer case is acting weird. If the rear wheels spin, the front almost never kick in. However the 4LO works fine and all wheels are spinning. I know there is no traction control of any form so I do not know what is going on there. No codes are there either.


Please help guys

kennzz05 01-15-2014 03:04 AM

Re: My dads '99 WJ laredo. HELP!!!!!!
 
are you saying that you are getting stuck in snow unless you put it in manually to 4 wd if not than the system may be working as intended

Frango100 01-15-2014 04:53 AM

Re: My dads '99 WJ laredo. HELP!!!!!!
 
The first problem seems to me engine related and not transmission. Could be a low fuel pressure due to bad fuel pump or TPS, however the last should have set a fault code.
For the second problem, is the jeep quadra drive or quadra trac II, then it has the NV 247 T case. This T case has a progressive coupler which should transfer the torque to the front wheels when there is a speed difference between front and rear. This coupler is probably shot. In 4lo front and rear are mechanically coupled and the coupler is bypassed.

Tuzmaster 01-15-2014 11:30 AM

Re: My dads '99 WJ laredo. HELP!!!!!!
 
We checked the fuel pressure and it was at 45 psi, changed the filter that did nothing. Could it be something else? To me it kinda feels like its trying to engage low gears all of a sudden, but because you are driving too fast, then it won't let it.

He has Qudra drive. So how do we get to that coupler? I am assuming we have to take the T-case off?

Tuzmaster 01-15-2014 11:31 AM

Re: My dads '99 WJ laredo. HELP!!!!!!
 
Quote:

Originally Posted by kennzz05 (Post 960062)
are you saying that you are getting stuck in snow unless you put it in manually to 4 wd if not than the system may be working as intended


And yes. Unless you are in 4LO, then on slippery roads you are not going anywhere. Rear wheels spin but front aren't

Frango100 01-15-2014 04:30 PM

Re: My dads '99 WJ laredo. HELP!!!!!!
 
The coupler is very expensive, you better look for a used T case with warranty.
If you have a scanner which shows live data, you could check the TPS position and see if it shows different values when the problem is there.

Tuzmaster 01-15-2014 04:49 PM

Re: My dads '99 WJ laredo. HELP!!!!!!
 
I am not good with acronyms. Whats TPS? Assuming throttle position sensor. My friend said that when they tested it, it was fine. engine and fuel are fine from what I got.

Frango100 01-16-2014 02:57 AM

Re: My dads '99 WJ laredo. HELP!!!!!!
 
Yes, TPS is throttle position sensor.
The tests where all done at the moment the problem was there?

Tuzmaster 01-16-2014 10:03 AM

Re: My dads '99 WJ laredo. HELP!!!!!!
 
Yes they were...

2005JGC 01-19-2014 01:04 AM

Re: My dads '99 WJ laredo. HELP!!!!!!
 
I just want to clarify, you tested the fuel pressure when it was acting up?

I agree with Frank, it sounds like a motor issue, if the throttle opens engines WANT to run, if you give it air, the computer will add fuel and you get more rpms, if opening the throttle does nothing, there is something engine/sensor wise going on there, but again, as frank mentioned, likely something unmonitored, like exhaust back pressure or fuel pressure to mention a couple.

Tuzmaster 01-20-2014 10:44 AM

Re: My dads '99 WJ laredo. HELP!!!!!!
 
The engine was rulled out.. the pressure readings were taken at the time of problem and was always constant 45 psi.

2005JGC 01-20-2014 02:29 PM

Re: My dads '99 WJ laredo. HELP!!!!!!
 
How was the engine or an engine sensor, or control (pcm) ruled out? A transmission has no say in engine rpm.


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