hey guys, just picked up my first jeep, its a 1989 cherokee pioneer.. its an automatic with the inline 6, my question is this.. when in drive (d) its terribly sluggish, almost no throttle response, its accelerates smoothly, seems bogged.. and thats even when mashing the peddle.. but slow as heck. if i put in in (3) or (1-2) from a dead stop, it accelerates fine, which is weird. there are other issues, but this one is really bothering me.. ive thought about the tps, but it seems weird that it would take off fine in (3) or (1-2).. any suggestions? thanks in advance from a new jeep owner

 

It sounds like a trans issue(assuming AW4) where it isn't selecting 1st gear when you put it in D. By putting it in 1-2 it will manually go into 1st. When you put it into 3 it would only select 3 IF the TCU is disconnected or fuse blown. If it is going into 1st when you try to start out in 3, then the TCU and fuse are in play.

With the TCU disconnected or fuse removed, if the trans seems to shift fine manually, you have an electronic issue. 1-2 should get you 1st, 3 should ge you 3 and D OD. It is possible to force the trans to shift from 1-2 by pressure, but that will only occur at 4500rpm or so.

There is also the kickdown cable, and its linkage is adjusted under the hood. Make sure its adjusted properly so as to take the slack out of the cable.

Other factors are the throttle position sensor, vehicle speed sensor, and brake pedal switch. The brake pedal switch unlocks the lockup. The TPS has 5v input, ground, and an output lead on the 3 lead variety. With the ignition on, but engine not running, determine which is input, output and ground, and then measure the output voltage as the throttle is opened. It should increase in a linear manner, otherwise, needs to be replaced. If you have the earlier TPS with 5 or 6 leads(?) they can be adjusted.

 

Think it might be the nss? I've already changed the tps and set it correctly

 

did you adjust the detent /kick down cable yet

 

hey guys i have the same problem i can drive around all day long she shifts fine if i stay WAY outta the o juice but if i hit it she does wanna show what shes got.very gut less.just need to know where to start.its on a 89 pioneer aw4 and 4.0.pls help its horrible when you get pasted by a old lady in a geo

 

sorry guys but 1 more? whats the nss

 

Hey it's been a while since I posted this but I figured I owed a response. It ended up being a simple 10 amp fuse under the passenger side dash that had been pulled by previous owner ( transmission control unit fuse) plugged it in and all was well! Since then I've done tps, starter, beefier adjustable lower control arms etc etc... And I had a problem with it not starting with a key but that was a dirty nss. And for the previous poster, the nss is the neutral safety switch, it's a clamshell shaped device plugged into the opposite side of the linkage of your tranny that tells your jeep if youre in drive or neutral and that its safe to start it. One bolt, one plug. Do a search on the forums here and I'm sure you'll find plenty of literature on it.

 

Neutral Safety Switch. It prevents your Jeep from being started in anything other than Park or Neutral and also provides some information to your transmission as well as close and open the circuit to your reverse lights.

Good to read that you've got it sorted out.