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'04 Jeep WJ | Engine/Trany Issues

11K views 26 replies 10 participants last post by  Jester86 
#1 ·
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 :(
 
#4 ·
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!
 
#10 ·
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.
 
#5 ·
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.
 
#6 ·
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.

POSSIBLE CAUSES
TP SENSOR SWEEP
INTERMITTENT CONDITION
(K7) 5-VOLT SUPPLY CIRCUIT OPEN
(K7) 5-VOLT SUPPLY CIRCUIT SHORTED TO GROUND
TP SENSOR
(K22) TP SENSOR NO.1 SIGNAL CIRCUIT SHORTED TO GROUND
(K22) TP SENSOR NO.1 SIGNAL CIRCUIT SHORTED TO (K4) SENSOR GROUND CIRCUIT
TCM INTERNALLY SHORTED THROTTLE POSITION SIGNAL CIRCUIT
PCM

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 N·m (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.

 
#8 ·
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.
 
#9 ·
Let us know! Mine just rolled 70k too!!! No problems yet though! (knocks on wood). And good luck!!!
 
#12 ·
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.
 
#13 ·
Well after talking to some friends I've decided to change the TPS, AdvancedAuto has a BWD for $34.99 and AutoZone has a Duralast for $45.99. Most of what I've read seems like neither brand is great but seems like Duralast is the least favorite.. what do you guys think?
 
#15 ·
Kinda off topic but for future reference you can get your error codes yourself in your wj. Cycle the key to the on position from the off position 3 times and it'll give you the codes where your odometer is on the third try.

A lot of people can get by just by cleaning their TPS, I had a really effed up idle (bouncing from 550 - 750) and I did that and all is well.
 
#17 ·
There is nothing to clean on the TPS. The IAC is really the only sensor that can be "serviced".

I say again- REPLACE THE TPS! The TPS , when faulty, will cause erratic converter lockup, which will feel like shifting.
 
#16 ·
Thanks for the info guys. Thats a good trick.. going to try that next time she comes on. As far as cleaning everything goes, I'm going to do it this weekend.. busy week of classes :( Love how the old Jeep i6 just keeps running despite the issues tho ;).. I'm still a little unsure about the highway speed issue I've seen in the past though. I put some transmission fluid "stabilizer?" from Lucas in it last week and I haven't had it happen since though it was an extremely hit and miss issue to begin with..
 
#18 · (Edited)
Well guys I just got the TPS changed out and also had to do a little plastic work. It seems as tho someone has had the manifold off in the past and resorted to a less methodical manor of removing it. They managed to crack the collar that slips into the gasket boot/ring that acts as a threshold between the manifold and the throttle body. A little epoxy fixed it right up tho ;) .. I also cleaned the throttle body and IAC. I started it up real quick and I'm still getting the check engine light. Does it take some time to clear out the old error or does this mean the error is still currently being flagged? I've considered replacing the IAC sensor.. Any and all thoughts welcome.. Error codes are still P0122 and P0123
 
#24 ·
Good news gang, the WJ is back up and running like brand new. Ultimately the TPS seems to have been the cause of all my issues though I also did change the spark plugs/boots & fuel filter and cleaned the throttle body & IAC port/sensor. Only down side is I managed to snap one of the throttle body bolts off in the block :-\ ... guess thats why you shouldn't work on a car at 4am.. aside from that all seems well though. Thanks for all of your input!
 
#26 ·
Hey sorry for the delay Sleepy.. I'll prob hold off for now simply b/c I'm a little strapped for cash after paying for all that other stuff and I'm about to go on a trip. Once I get some money back in savings I may see if you still have it tho. Part of me is considering selling the WJ and getting a JK tho.. I just like the way a jacked wrangler looks over a WJ..
 
#27 ·
So update on the WJ.. It still appears as though the TPS was the issue b/c she's running great now! Thanks a lot guys! One thing I've noticed since changing the fuel filter though is that I seem to be hearing a lot of fuel noise. It only happens for a short while after starting after its sat for an extended amount of time. I don't know if the noise is due to fuel passing through the filter or if for whatever reason my pump is now acting different. I put a WIX in it if anyone's had a similar issue. Its not overly annoying or anything, I just want to make sure its not a sign of another future failure. Perhaps its even done it in the past and I just didn't notice it then...
 
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