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Christine.Bachtell 06-15-2013 07:33 PM

Transmission problems
Hi my name is christine and I recently purchase a jeep grand Cherokee limited 2005 and I've had nothing but problems with it since I bought it. I've had it at 3 different shops and no one knows what's wrong, it constantly is shifting in and out of gears roughly and revving while idling and sometimes shuts off while idling or while I'm driving ! I have 2 codes that I got out of it finally but no one knows what they mean.
U0401 - implausible data received from engine control module / power control module
P0068 - manifold absolute pressure / mass air flow throttle position correlation
These are the codes I was given but I don't want to be throwing money into it without knowing exactly what it is.
I can't even merge onto the highway without having to smash the gas pedal because I literally have no power ! Help !

Frango100 06-15-2013 08:33 PM

Re: Transmission problems
2005JGC probably can answer this better, but let me give it a try. Just as a start, which engine/transmission?
The p0068 means that the correlation between the MAP sensor signal and the TPS is not within the normal limits. This can be caused by a vacuum leak at the intake duct/manifold. Don't think though that this would cause the shifting problems. The TPS however for sure will cause shifting problems when its getting bad.

Christine.Bachtell 06-15-2013 08:57 PM

Re: Transmission problems
Yea idk I had it at a transmission shop for almost 3 says and they couldn't figure it out but it doesn't do it all the time so my bf thinks its a sensor going bad. I'm just sick of having no power and it shifting weird

Frango100 06-16-2013 09:01 AM

Re: Transmission problems
So did they check the TPS sensor and wiring? The erratic idle, shifting problems and power problems all point towards the TPS.

YJ John 06-16-2013 09:21 AM

Re: Transmission problems
I had the same two codes on my 2006 Hemi, changed the MAP sensor and all is good. I did find the new MAP sensor, I got from the dealer, had changed shape from the old, the intake manafold had a tab I had to cut off to get the new sensor in place.

jeepgcoman 06-30-2013 02:19 PM

Re: Transmission problems
Christine, have you fixed your problem(s) yet? If so, or if not, I agree with the above...change the MAP Sensor, if for no other reason than to take it "off the table" as a possible problem. They only cost ~$25-30. If yours is a Hemi, like YJ John said above, the one you buy will be different from the one that is in there now, as they are now all the "late model" style. You will have to cut tab(s) off the sensor and maybe the plastic gusset on the intake manifold to get the new one to install correctly. Also, as asked above, which engine do you have in it, and how many miles are on the vehicle?

No matter which setup you have, since you just purchased it, you should do (or have done) a complete service, so you know where you stand, service and maintenance wise. This doesn't have to be done all at once, but should be done, servicing the important/most critical stuff first, depending on vehicle mileage. Since you're having shift issues, I would start with a complete transmission service....both filters and new ATF+4 fluid.

Either DIY, or find a reputable independent transmission shop to do the work....not AAMCO, the stealer, or the like. Try to be there and see the pan when it comes off, so you can verify what it looks like when emptied. There should be nothing on the magnet, no debris in the pan, maybe just a slight dark colored film that will wipe off with your finger or a rag.

For this one, you'll either have to go to the stealer or invest in one of the Diablosport Tuners. Have the PCM/TCM updated to the latest CALID flash files for your particular model. Chances are good that it has never been updated since built. Here's where you can find the (almost) current list of files for your vehicle: Updating these files should help eliminate some of the "known" issues with your model. The stealer will usually hit you ~$100+ to have this done, and a Diablosport Tuner will run you ~$300-500 new, or you may be able to find an "unmarried" used one for somewhat less. The tuner offers many other tuning/performance/mileage capabilites that may be of interest to you.

If you're having idle issues, and perhaps low speed surging, poor performance and/or economy, you may want to change the EGR Valve (~$30-50), as this is a fairly common problem on vehicles with ~60K> on them.

Other issues (if you have the Hemi) are proper weight oil (must use 5W-20, preferably a good synthetic), proper spark plugs (must use a quality copper core plug), and the "wasted spark" system on the 05's where the spark plug wires cross over the top of the engine. The proper weight oil is needed to insure proper operation of the Multi-Displacement System (MDS), irridium or platinum plugs many times cause misfire issues, and the spark plug wires deteriorate with age, also causing misfire issues. Many of us with 05 Hemi's have removed the wires over the top of the engine and gone with Taylor Shorty wires: Taylor 82041 Taylor ThunderVolt 8.2mm Custom-Fit Spark Plug Wires= There are a number of places you can purchase them, but this is an OK source. You may want to do a Google Search for pricing (and maybe wire color) purposes.

There are a host of other things that should be looked at on a "new to you" vehicle (diff./xsfer case, coolant, air filter, etc), but the above are fairly important, and probably should be addressed sooner rather than later.

Good luck with your new vehicle and keep us posted on your progress. Like most vehicles today, you take good care of them and they'll take good care of you but, unfortunately, it's never going to be cheap.

Contrabassoon86 06-30-2013 08:42 PM

Re: Transmission problems
Thanks for the great write-up!

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