eratic trany shifting (kinda long but i need input)

this has been steadily worse for the last few weeks and i cant take it anymore!!
98 XJ, 4.0L, AW4..
it started a month or so ago with what i would call an "intermittent stumble" on the highway.. in the course of an hour it might do it twice at that point. would feel like someone had a strap to the back of my rig and would give a quick gentle tug on it. most of the time it was gentle enough i'd only feel it in the seat.. slowly got worse and sometimes around town it would idle fast and give me a high shift point.. at this point i was getting an intermittent "check engine" light.. the clown at The Zone told me i needed a new fuel cap (and in light of fuel prices i bought a locking cap so he wasnt totally wasting his time)
my gut told me to do a new TPS at that point, it "seemed" to fix it.. for about a week..
the problem returned as a highway issue but it felt like a harder "jerk" on the imaginary strap behind me.. i started thinking fuel pump related..
then on a road-trip to Pa 2 weeks ago i figured out it seems to be throttle-sensitive or at least throttle-position-sensitive.. level ground 70mph relatively fine.. increasing throttle as i start up an incline would almost guarantee a few jerks.. sometimes pretty hard. increased throttle would make it stop, keeping it in the "spot" would keep it jerking sometimes.. at that point it was still just a highway issue..
this week it got worse and is acting up most of the time.. cold idle and drivability seems ok, but after it warms up it gives me a 1400 rpm idle, 1-2 shift at an easy part-throttle is at 2800 RPM and 2-3 shift is around 3500 RPM... it will shift right away if i lift the pedal though. one other thing i'm feeling now is that as i come to a stop it feels like the trany or convertor isnt unlocking/slipping properly and drags the engine RPM down lower than normal idle and it stumbles for a second or 2.. check engine light is on at start-up most of the time, but sometimes it doesnt come on at all.. at this point i'm spending 75% of the time in these operating conditions other 25% it might run fine for no reason..
i'll swap the TPS again just because its got an warrantee on it from Advance, but i'm thinking its a trany module issue.. i had thought that the tranny was controled by the OBD system in the later XJs but i found something in a manual refering to a TCM up under my dash..

i guess i can admit to ignoring the issue because i'm waaay to damn busy but i think i'm running down to the trany shop where we get our tranys from for our shop and see what he has to say..

i spelled out pretty much everything i can about this.. except ive had the rig for about 4 months now and it "seemed" ok for a while.. but i cant see how a dealer could hide a problem like this just to get it off his lot.. so i'm calling it wear-and-tear..

its ur solenoids. mine did the same thing. and it still is

although I would never rule anything out on a Jeep, it sounds a lot like the problem I have been chasing for a couple months off and on. I finally got serious and started chasing wires and found the wires to the TPS had chafed and were intermittently shorting against the intake and causing loss of signal to the ECU. Check the input and output voltages and give the wiring harness a good "wiggle test" with your third or forth hand.

98RExj said:

its ur solenoids. mine did the same thing. and it still is

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i still havent been able to tell if its the convertor unlocking rapidly or the trany itself.. RPM doesnt seem to jump hardly, if at all, when it happens...

sidriptide said:

i still havent been able to tell if its the convertor unlocking rapidly or the trany itself.. RPM doesnt seem to jump hardly, if at all, when it happens...

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it might be your "lock up" solenoid.

X2 on the wire wiggle tests. I would check the ignition wires too, just to make sure it's not the engine dropping out with a missfire, arcing HV wire.

Sure sounds like a bad TPS, but if not, that leaves chasing wires from the PCM to the TCU and then to the tranny solenoids to find a bad wire or harness connector.

There are some good recent threads here with ohm meter and wire ID data for testing the TCU wires and the tranny solenoids right at the TCU!!! Search my user id ( Ecomike) or lawsoncl for the threads.

i tested the TPS with a multi-meter and is seems to be within specs. i disconnected the battery for another project and reconnected just before i left the shop.. it ran perfectly fine for the 20 minute ride home, but that didnt include any highway.. lets see what i get on the morning commute.

sidriptide said:

i tested the TPS with a multi-meter and is seems to be within specs. i disconnected the battery for another project and reconnected just before i left the shop.. it ran perfectly fine for the 20 minute ride home, but that didnt include any highway.. lets see what i get on the morning commute.

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by the time i got to work today it was acting up again.. not liking to stop at lights, higher shift points and high idle...

Did you use an analog volt meter on the TPS and test for noisy locations on the throttle position sensor where the voltage signal is not smooth? Also test it when it is hot, and has just malfunctioned on a drive (leave it running hop out and wiggle the wires....take some meter readings)

Ecomike said:

Did you use an analog volt meter on the TPS and test for noisy locations on the throttle position sensor where the voltage signal is not smooth? Also test it when it is hot, and has just malfunctioned on a drive (leave it running hop out and wiggle the wires....take some meter readings)

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i couldnt find my analog meter, but i was thinking maybe there is a "dead spot" somewhere.. i'll be back under the hood tonight snooping some more.. thanks!!

sidriptide said:

i couldnt find my analog meter, but i was thinking maybe there is a "dead spot" somewhere.. i'll be back under the hood tonight snooping some more.. thanks!!

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I have seen them at Radio shack and Harbour Frieght for under $20. They work well on O2 sensor testing too!

heres a quick update.. the problem hit an all-time low on sunday last weekend. i was the highway and the "jerking" got to the point that it was basically constant.. and twice it actually felt like it stalled for a full second.. limped it home and went right to the trany shop. the best way to describe it is like the convertor is repeatedly locking/unlocking... the trany shop drove it and ran the diagnostic computer and it couldnt pinpoint any problem besides a possible fluctuation in voltage going TO the TPS. after testing the ignition coil i started digging around in the harness looking for a bad wire or connection i started it up and started testing voltages on stuff.. then i realized that the annoying squeeling thats been coming from my accesory belt recently is coming from my disributor!!!! wtf..... pulled it out and the shaft has a stiffness/binding on 1/2 of its rotation. cant tell if its actually bent but i cant see how that would happennnn unless the camshaft was walking.. (hmm, maybe thats my valvetrain noise?)
i swapped in a spare distributor and it seems to be all gone now... 7 or 8 test drives on the highway with no issues... i'm still debating driving it to Pa this weekend but i'm thinkin i'll be fine...

sidriptide said:

i'm still debating driving it to Pa this weekend but i'm thinkin i'll be fine...

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famous last words... it was "ok" for about 1 day then on my road trip it acted up and is now as bad as it was last week when i sent it to the trany shop. i've isolated the culprit to being inside my steering column now. it "bogs" any time the wheel is turned to the right of neutral-center even a small amount. without tearing into the column i'm thinking it must be in the directional switch since it doesnt do it at all when the wheel is left-of-center. i never really made a connection to the position of the wheel before but it is definately the source. when i move the wheel to the right it is shorting something out.. the dash doesnt go dead, but the engine falls on its face instantly. i cant tell if it's the fuel pump shorting out or the TPS maybe. as it sits right now i'm looking at a CE light all the time and a 1300 rpm idle as soon as it warms up.
anyone ever heard of this??

Do you hear the steering pump bog down when it happens? If so it might be a problem in the steering gear box or binding linkage.

How about the ignition switch and wires on the steering column?. Also check wires laying on the steering shaft under the hood.

Recheck the new dizzy too, that problem might have come back if it is a cam problem.

Ecomike said:

Do you hear the steering pump bog down when it happens? If so it might be a problem in the steering gear box or binding linkage.

How about the ignition switch and wires on the steering column?. Also check wires laying on the steering shaft under the hood.

Recheck the new dizzy too, that problem might have come back if it is a cam problem.

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i wasnt sure how it could have been the dizzy but it seemed to answer the problem.. maybe the extended disconnecton of the batt reset it, it's worked before.
i am positive its inside the column, thinking back now to a month or so ago, i replaced the directional switch because my left-turn would flash BOTH rear lights.. new switch fixed that issue..
i have an under-lying electrical issue in my column.

HOLY CRAP!! i think i solved this!!!!

(now that i've jinx'd myself i'm really screwed... )

i went as far as stripping everything electrical off the steering column except the air-bag and it was still cutting out!! there was NOTHING electrical on the column to short out!! WTF?!?!? i got tired of chasing this issue with no success so i sent it to a local shop where an experienced Jeep tech works. it was still idling high, cutting out on right turns and just running like crap with "check engine light" on..
his quote to me after an hour of scanning it (it was throwing 6 codes for TPS, TRS, TCSPL, purge valve, torque convertor clutch, and TCM all "malfunctioning" or incoorect voltage) and chasing wires.. "dude, you're F'd, it's in your harness somewhere" so we agreed it wouldnt be cost-effective for me to pay him to tear deeper into the harnesses so i brought it back it ran fine but i had NO OVERDRIVE now. back into my shop and stripped every bit of conduit and black tape off the under-hood harness and replaced/cleaned all the ground wires i had already done and a few i didnt know were there..
still no change, it ran excellent but no O/D..
i found a good site with wiring schematics (www.alldatapro.com) and just traced wires on paper for an hour looking for a common ground wire or something but all those sensors are grounded back to the PCM individually.....
so what else could they have in common???

POWER SUPPLY!!!!!!!!

i saw the TPS shared a power source with the revesre lights.. ran out and sure as $hit!! NO LIGHTS!!
further look at the diagrams showed that the small 15 amp fuse in the passenger kick panel labeled as "back-up" shares power with ALL those other sensors....
so what happened? it seems the fuse from that location was apprently plugged back into a spare location last week when we were going crazy looking at everything possible....
plugged it in the proper place and it runs excellent.. CEL went out after 15 minutes of driving and it "seems" to be gone...

so by the time i solved the last problem it wasnt even the problem i started chasing in the begining!!!!!
so i dont even know what cured the cutting-out issue... not for sure, but i'm confident it was a harness ground wire... somewhere..

so i'm just gonna sit here being happy till the next stupid issue come along...

Can't imagine any legitimate reason they would run rear back up lights off the PCM power to the sensors. Really odd. I've found similar fuse mistakes myself.

What are TRS, TCSPL?

Wiring diagrams are great help at that stage. More people should use them.

Congrates!