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Jester86 03-01-2010 02:38 PM

'04 Jeep WJ | Engine/Trany Issues
Hey guys, recently my Jeep as become moody. She's a Freedom Edition, i6 4.0L, Quad Track 4x4.. etc. She just rolled 70k and has been acting strange. Gas milage seems to have worsened noticibly, RPM drops below 500 ultimately leading to a stall, seems to start missing when reved to ~4k rpm, Shifts down at random while traveling at highway speed.. only stays down for a couple seconds then usually jumps right back up. I've done the normal quick tune up stuff, plugs, plug boots, Air/Oil Filters.. all FRAM tough/ext. guard. I got a check engine light to come on on the way to school today so I'm going to take it to AutoZone tonight and see what she's reading but I was wondering if anyone had any ideas or if anyone had a similar issue in the past. Please feel free to give me any and all input. I've done some reading that suggests in some of the 04 WJs the Crankshaft Position Sensor failed and was recalled but not per my VIN :(

robpp 03-01-2010 03:03 PM

Re: '04 Jeep WJ | Engine/Trany Issues
o2 sensors gone bad will send the gas mileage way down

Jester86 03-01-2010 03:06 PM

Re: '04 Jeep WJ | Engine/Trany Issues
You think it'd explain the other issues as well?

brooke 03-01-2010 03:09 PM

Re: '04 Jeep WJ | Engine/Trany Issues
I'm just going to say get that engine code read... I certainly hope you don't have the problem I had (cylinder misfire)... that led to a whole ton of $$ and trouble!

Jester86 03-01-2010 05:31 PM

Re: '04 Jeep WJ | Engine/Trany Issues
Alright well guys/girls, here's the skinny.. computer was flagging on two error codes (P0122 & P0123).
P0122: Throttle/Pedal Position Sens A Ckt Low Input
P0123: Throttle/Pedal Position Sens A Ckt High Input
My Jeep also failed to communicate during an 02 test which would lude to the senor being fowled however it did not flag on it nor did it show any other O2 related issues aside from failing to run the test. In addition I had some other tests return "LOW", tests: $53, $51, $31, $11.
I don't really know what those last ones point to however I am going to start by trying to clean the throttle body out w/ some CC and run some injector cleaner through it for a few tanks of gas. As always, any input is welcome. Thanks guys/gals.

brooke 03-01-2010 05:37 PM

Re: '04 Jeep WJ | Engine/Trany Issues
Sounds like TPS replacement... it's like $40 (Autozone, etc)...

P0122 - Set Condition: Throttle Position Sensor voltage at the PCM is lower than 0.1 of a volt for 1.3 seconds.


All the info I found said to clean it first. If it happens again, replacement of the TPS may be necessary.

3 = TPS
4 = IAC

TPS Removal 4.0L
The TPS is mounted to the throttle body.
(1) Remove air cleaner tube at throttle body.
(2) Disconnect TPS electrical connector.
(3) Remove TPS mounting screws
(4) Remove TPS.

TPS Install 4.0L
The throttle shaft end of the throttle body slides into a socket in the TPS (Fig. 34). The TPS must be installed so that it can be rotated a few degrees. (If the sensor will not rotate, install the sensor with the throttle shaft on the other side of the socket tangs). The TPS will be under slight tension when rotated.
(1) Install TPS and retaining screws.
(2) Tighten screws to 7 Nm (60 in. lbs.) torque.
(3) Connect TPS electrical connector to TPS.
(4) Manually operate throttle (by hand) to check for any TPS binding before starting engine.
(5) Install air cleaner tube to throttle body.

Scottina06 03-01-2010 05:58 PM

Re: '04 Jeep WJ | Engine/Trany Issues
good job Brooke! +rep for you Jeep sis!

Chuck 03-01-2010 06:00 PM

Re: '04 Jeep WJ | Engine/Trany Issues
Yeah I know P0122 means you have to most likely change the throttle positioning sensor aka TPS (I have the same code and I have to change mine one of these days) Not sure about your other problems.

Big Perm 03-01-2010 09:30 PM

Re: '04 Jeep WJ | Engine/Trany Issues
Let us know! Mine just rolled 70k too!!! No problems yet though! (knocks on wood). And good luck!!!

Motteler621 03-01-2010 10:31 PM

Re: '04 Jeep WJ | Engine/Trany Issues

Originally Posted by brooke (Post 161109)
I'm just going to say get that engine code read... I certainly hope you don't have the problem I had (cylinder misfire)... that led to a whole ton of $$ and trouble!

yea I had a cylinder 2 misfire for awhile on my honda. Took a week for them to figure out what the problem. I cant remember what they replaced but it was some part and then the lines were packed with carbon. It took them a week to figure out that it was packed with carbon because it kept misfiring after replacing a part. But it was only like 250-300 to fix altogether.

FlyinRyan 03-01-2010 10:52 PM

Re: '04 Jeep WJ | Engine/Trany Issues
replace TPS, clean IAC at minimum, go from there. you will likely have an O2 sensor to replace as well.

Jester86 03-02-2010 11:50 AM

Re: '04 Jeep WJ | Engine/Trany Issues
Thanks for the input guys. I'm planning to clean the TB and IAC, and test the TPS w/ a multi meter tho I'm tempted just to go ahead and replace it since it seems to be an in and out issue it may not appear defective when I test it... unless I can tract a fault within the wiring itself. Aside from all that, do you think a combination of the TB, TPS, IAC and O2 could be causing all of my issues? Seems like it could be the low RPM issue but the high RPM misfiring at 4k rpm seems almost like a timing issue though I'm sure a slue of problems could have a hand. What really has me wonder is it shifting down while on flat highway traveling a constant speed. It only holds down for a second and then jumps back up a gear. Its extremely hit and miss, happens maybe once/twice a month. I'm planning to get the trans flushed sometime in the next couple weeks so that may help a little.. I'm planning to go on a roadtrip in mid/late March and would like to have all this taken care of by then... Oh yeah.. and my check engine light turned itself off again this morning.. Do you think it may just be a wiring/connection issue w/ the TPS. I would almost think if the TPS itself is flawed it'd be more of a constant issue.

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