Rushin

Hey Everybody, cross posting this with about 3 other forums. Trying to get as much input as possible.


I am having issues with my TPS. I got a 1990 Jeep Cherokee (AW4, Renex, 140k miles) and started doing some preventative maintenance on it. I replaced spark plugs and wires and distributor and the cap. All of that helped with starting issues that i had as well as hesitation when accelerating.

One thing all of this did not fix was a strange stutter i get when being very light on the throttle. I get the stutter when i am in D or 3rd or 1st. Another issue is the transmission does not shift right away when i push the throttle and when it does even if i keep my foot on the throttle transmission shifts too early back to the higher gear.

I right away thought my TPS is bad. So i took the voltmeter and tested the TPS input and output voltages. for input i get 3.6v and for output i get 0.14v with the throttle plate closed and 0 when throttle is fully opened. so numbers are totally wrong.

So what i have done so far to troubleshoot is:
1. I tested the TPS power wire (A at square tps plug). A to D shows 3.6v (~5 is what it should be).
2. I put positive lead from voltmeter to A and negative to a known good ground and got 4.6v.
3. I tested both TPS ground wire and TPS power for continuity. Put positive lead of voltmeter to the plug on TPS (A) and negative lead on corresponding connector on TCU harness at TCU. I got a chime from the voltmeter.
4. I put positive lead of voltmeter to the tps power at TCU and negative to tps ground at TCU and got 3.6v.
5. I put positive lead of voltmeter to tps power at TCU and and negative to TCU ground and got 4.6v

i did the Ohm test on the C5 and D7. Two of the wires at the dipstick got wacky reading. Like one got 1 and the other got like 12, 13, 14 and growing and then went to 1. The other one got a reading of -1.88 when i had the positive on the c5 (same for d7). The wire that goes to the dipstick had about half inch of exposed wire. And it looked quite a bit corroded. The eyelet had two wires going to it. Here is a pic of it. It looks rough and corroded. Could this be the issue ?


I did put an extra ground on the TPS ground wire on the TPS plug side. The extra ground i routed to the firewall and made sure it was good. That did not do anything and the reading was still 3.89 volts , measuring with the plug connected and testing from the back of the connector.

I followed the All Data flow chart for TPS testing. When i got to the end it said replace TCU. So went to U pull and got 4 TCUs for 20 bucks and all four show the exact same results.

I did try a new TPS and get same results.

I cleaned and battery terminals, replaced the back of the head ground strap with a thick 4 gauge wire, cleaned the dipstick grounds with sand paper. I sprayed both grounds with anticorrosion spray.

I am pretty much out of ideas.

I feel like the only answer here is to totally unravel the whole harness, which i really dont want to do.

freegdr

what are you basing your readings on as to be backwards

EVcherokee

Search for it, theres a million write-ups on tps problems

freegdr

im asking him that to see if hes in the proper scale of readins for a renix ?

Rushin

Not sure what you mean. I used All Data flow chart and followed their directions to how to test tps. I have been searching for weeks reading every single website and thread about this issue but nothing is helping. I just don't know what else to do.

freegdr

the renix manual i have has certain perimeters tha the swith should operate in for the renix vechicles

freegdr

was the aldata information for renix jeeps

Rushin

yes it was.

Rushin

New issue now appeared when it got colder out. When I start the car in the morning and shift into reverse it takes a few seconds for the gear to endage. It does it with somewhat of a jerk. It only happens in reverse and only when it's cold. I have been reading online about this and it looks like it's somewhat common issue on auto transmissions. What usually causes this? Fluid not up to temp?

I have not done anything to the tranny yet. I am going to replace the fluid and filter sometime soon. Btw, what is the proper fluid is it the ATF+4 or Dextron. This is again for a 1990 with aw4.

DesertFox4x4

DEXRON III

Rushin

Than you. How much does the tranny take? Is it filled through the tranny dipstick?

Rushin

Well pretty sure the issue is almost fixed. Me and mn-jeep member spent a few hours today going through a bunch of stuff trying to figure out what was causing my stutter.

We determined that, first of all, my damn voltmeter that i was using for the past 4 years has bad leads so it was reading about a volt and a half low. How freaking stupid is that. So my TPS harness and TCU are totally fine. But the TPS on the car was bad and was way out of adjustment. So good thing i bought a new TPS just incase.

So we popped a new tps in and got it to adjust perfectly. Took the truck for a spin and it started to shift and idle way better. But the stutter was still there. For a minute Jason thought it could be a mechanical issue with my rear end or tranny.

We get back into the garage, he checks the rear end, it its fine no play in drive shaft, no chipped teeth in the diff.

Thats when we decided to order pizza and have a beer :-).

Jason said we should check my plugs and wires. As soon as he got the plugs out he said that the plugs i got are not the best (Platinum Bosh). And the wires were way loose on the cap and the plugs.

Plus while the plugs were out we did a compression test and got 125 on all cylinders except the front one, that one was 115. 125 seems pretty low but at least its pretty consistent.

Ate Pizza.

Parts arrived and we got new plugs in and new wires in. Took the Jeep for a spin. What a difference, the stutter was almost gone. I could only notice a very little misfire when driving home for an hour and a half at about 70mph for about a millimeter on the gas pedal.

So my thought is that this all was caused by bad wires and plugs. Wires were ****ty NAPA wires that did not fit snug enough around the plugs and distributor cap.

The remaining stutter is a miss that i am pretty sure is caused by a faulty distributor.

One little detail i forgot to mention before i even posted this thread is that previous owner had a valve cover explode on him while doing a 500 mile drive. He only noticed it when he smelled raw oil inside the car. So when i got the car and replaced the distributor cap it was full of oil. My thought is that oil might have damaged the distributor.

So i am going to get a used distributor and see if this cures the rest of the miss i got.

Rushin

well guys, i spoke too soon! Drove the truck to work today and it backfires like crazy in every gear. If i go over 1800rmp and try to hold it there it bucks, stutters and backfires. This is for sure not the tps. This is a serious misfire. So my bet is still on the distributor or something to do with the ignition.

Rushin

Pretty sure I fixed this time. Replaced the pickup coil. The engone fired up right away no more cranking for 5 seconds. And i took it for a ride and it was smooth.

freegdr