Possible TPS problem ??

[TRCM]

96 cherokee sport......​

During a recent road trip, I noticed I'd be crusiing along doing 1800 rpm @ 55 mph (apparently normal for my jeep), and then suddenly with no reason at all, the rpm would jump between 200 & 600 rpm.​

When it did this, if it jumped 600 rpm, I lost kickdown, but if it jumped 400 or less, I could barely, and I mean barely push the gas pedal, and the tach would rise ~ 50 rpm, then drop into lockup & OD backdown to 1800. Also, sometimes, when I tried to get it to kickdown, like climbing a hill, it'd just stay in lockup and lug the motor.​

I also noticed that if I stopped the jeep, killed the engine, and simply disconnected and reconnected the TPS wiring, it would drive fine for maybe 10 or 15 min, then start acting up again.​

I'm thinking TPS has a bad spot in it..........any other ideas ??​

 

[sidewaysstarion]

Could also be a brake switch, if you tap the brakes when you're driving in 4th gear it will unlock the torque converter.

 

[Tim_MN]

Test the TPS. Test the brake switch theory. Go for a similar drive, when the symptoms occur, carefully put you foot under the brake pedal, lift it towards you and hold it. What happens ?

 

[TRCM]

If it was the brake switch, how would accel pedal position change it ? And cause it to go into lockup again ?

 

[Digger87xj]

I think your diag is spot on.

 

[TRCM]

Ok, new TPS didn't fix the problem, and the brake switch seems to have no effect either.


It takes about 15-20 min of driving for it to start.

And no codes are set





Any more ideas on what to look at ?

 

[Tim_MN]

Low/dirty/incorrect trans fluid, faulty TCM, incorrectly adjusted trans kickdown cable (actually a throttle valve cable).

 

[Digger87xj]

MAP sensor maybe?

 

[sidewaysstarion]

MAP sensor maybe?

Map sensor only effects fueling to the engine and has no relation to the transmission.

 

[Digger87xj]

Map sensor only effects fueling to the engine and has no relation to the transmission.

engine performance is directly proportional to transmission performance. MAP can very well affect transmission shifting.

 

[TRCM]

Well, the probelm is getting worse, and today, for a short time, it only had 2nd gear and reverse.

So far, the following haven't helped:
adjust kickdown cable
check fluid (fine level & smell/color)
new tps
new map
new brake switch


I am just about convinced it is the solenoids in the trans at this point.

 

[Pchitti]

Def sounds like it went into limp mode. I would doubt its anything outside the tranny. Possibly tcu?

 

[Runnin'OnEmpty]

How about the TCM? Maybe loose or corroded connectors
there? An easy check would be to remove the connectors,
spray with WD-40 and reconnect.

It's strange that disconnecting/reconnecting the TPS
would fix it for a few minutes...makes it sound like a
poor electrical connection somewhere.

 

[TRCM]

How about the TCM? Maybe loose or corroded connectors
there? An easy check would be to remove the connectors,
spray with WD-40 and reconnect.

It's strange that disconnecting/reconnecting the TPS
would fix it for a few minutes...makes it sound like a
poor electrical connection somewhere.

Well, it wasn't just disc/reconnet the tps.

I also shut the engine off while doing it to avoid getting a check engine light.

Shutting the engine off would also reset everything, including killing power to and then restoring it for the solenoids in the trans.

And the time it only had 2nd was right after a hard, tire spinning uphill climb on a muddy hill.

Seemed to work ok (or like it has been I should say) the rest of the day after about 30 min of 2nd gear only, including the 100 mile trip home, where most of the time it was only 200
rpm above normal @ 55.

And no codes during any of this either

 

[jeremyj]

Any progress? Mine's been doing similar things for a while and I can't figure it out. I've thrown tons of money at it and nothing helps.

 

[Jesse_Hallum]

Poor TPS connection? Try blasting it with electrical contact cleaner, and tighten the individual plugs with a small screwdriver.