New TPS finally came. Installed and adjusted. Jeep drove fine for about 10 minutes. Just driving around the block mainly trying to make the problem start. Seems to occur when the Jeep is coasting more often than when it's accelerating. Drove for about 30 minutes and the high rev/1st gear issue came up twice. I pulled to the side of the road, put it in park, then D and started out and sometimes it would start working fine again.

I still don't think the WOT is kicking down. If I give it a moderate amount of pedal, it will accelerate quickly. If I stomp it to the floor, it seems like its searching for the RPM but not making it if that makes sense. I'm going to clean up the dipstick ground again and move the battery cable to the stud forward of the dipstick stud. The other grounds can stay on the dipstick stud. Engine is running well though. I do have a spare TCU so I could swap that out too.

Any other things to try?

 

What method did you use to adjust the TPS?
Why not put the ground right at the dipstick tube stud with the small ones?

 

For the TPS, I put the new one in. On the flat connector, got 4.9V from A-B. Then I pivoted the TPS so that I could get approximately 0.83 on the B-C. Worked out to about 0.86. I wasn't sure if I should do this with the 4 wire connector instead since I am having trans issues. Please advise.

The grounds are all on the dipstick stud now but I was thinking that the large wire from the battery may be better off on its own stud. It shouldn't make a difference really but it might look neater.

I have a spare TCU but it's used so I don't know if it's good or not. Do the TCUs go bad frequently? I used a chart from another poster on the TCU (transonline.com). On the TCU D7 pin, which should be ground, it showed about 8 ohms resistance between vehicle ground and D7. Would this be ok or should it be the same as the TPS ground - negative battery of 0.8 ohms like I had now. Shift solenoids all read between 11-15ohms when probed from the connector with the TCU unplugged.

 

Should check the trans side connector as you think.
Neater looking and easier to do with the negative cable.
TCUs go bad rarely.
I don't like the 8 ohms resistance you're seeing.

 

Not to disagree with cruiser whatsoever, just wanted to mention the PO of my Jeep was sold a TCU. No idea on the details, or what was up with that.

.8, less than an ohm is acceptable resistance for the sensor ground...I think.

 

He says 8 ohms from D7 on TCU to ground.

C5 to ground. What's the resistance there?

 

Thanks for the replies-I'm not liking that 8 ohms either so I'm going to run that back. I'm thinking that the back of the C101 connector goes along the back of the engine bay and through the firewall to the ECU and TCU. So if my ground on the TPS side is good, I'm thinking it's the wires along the back of the engine and into the inside of the Jeep. I will check the other "grounds" on the TCU. I wasn't sure if they should be the same as the vehicle ground but you've both basically confirmed that ground is ground.

An intermittent issue usually points to a ground/short type issue so I'll focus on that now that I have a new TPS. I will also adjust on the TRANS side instead of the engine side to see if there's a difference.

Keep the ideas coming. It's keeping me up nights as it is and I'm running out of time to get the safety done before the kids get back to school and we need that second driver!

 

D7 doesn't go through the C101. It goes to the dipstick tube stud but is crimped into the C5, which is the ground for the shift point logic, before that.

There is a C104 connector near the right hand shock tower that the ground passes through also. You might conside this while you're at it:

I suggest unplugging EVERY electrical connection in the engine bay you can find, whether engine related or not, and spraying it out with a good electronics cleaner, visually inspecting the terminals making sure they haven’t retracted into the plastic holder, and then plugging it back together. There’s a critical 10-pin connector for the front lighting system located in front of the air cleaner and behind the left headlight assembly. Don’t miss that one. Also be sure that the connectors to the ballast resistor mounted near the air cleaner housing are clean and tight.
ALL of the relays should be removed, the terminals wire-brushed until shiny, and the receptacles sprayed out with contact cleaner. Then plug them back in. I do this on every Renix Jeep I purchase or work on for someone else.
Revised 07/23/2012

 

Yea, ground be ground, No if's, and's or butts. It's all one, connected, the cahssy/body, the neg terminal and that whole harness with the handy MAP terminal. I can only "parrot", stuff I've learned from Cruiser and others on the puter' stuff. Since we keep different hours sometimes that helps.

For testing..ANYTHING, (taillights come to mind as well), you can always run an old vacuum cleaner cord or any good wire right from the bat neg to whatever you want to ground. That can be quite enlightening if you sucessfully ground something that didn't have it before.

 

I thought I woudl neaten up the dipstick ground and put the negative battery cable on it's own engine block stud. The TPS ground (at the trans connector) went to 15 ohms! So, I got my Dremel out and wire wheeled the bolt and hole and wirebrushed and cleaned all the grounds again. Re-did the negative cable from the battery crimp to the dipstick stud. Nice grounds now. Also cleaned up the braided connection at the rear of the engine that goes to the firewall.


When the engine was cold this morning, I took it to the store and it drove fine there and back. An hour later, I took it out and it acted up right away. Sadly, shifting on the transmission was not impressed by all these better grounds. Took the TCU fuse out and transmission works in limp mode. Could it be the transmission speed sensor? These seem a little pricy ($100-125) to swap out just for kicks. Any way to test this to rule it in or out.

I feel like I'm close to the solution.

 

Sorry if you've already addressed this- but have you adjusted the TV cable (from the throttle to the trans)?

And- you might consider adding a good ground wire from the chassis to the transmission case. The solenoids don't ground very well through the trans harness back through the TCU, that's a marginal setup at best.

 

What is the TPS ground now?

You oughta do this test:
Cruiser’s Renix Sensor Ground Test
　
This sensor ground circuit affects the CTS, TPS, IAT, MAP, ECU and diagnostic connector grounds. It’s very important and not something to overlook in diagnosing your Renix Jeep as it is common for the harnesses to have poor crimps causing poor grounds. If any or all of the sensors do not have a good ground, the signal the ECU receives from these sensors is inaccurate.
Set your meter to measure Ohms. Be sure the key is in the OFF position. Using the positive (red) lead of your ohmmeter, probe the B terminal of the flat 3 wire connector of the TPS . The letters are embossed on the connector itself.
Touch the black lead of your meter to the negative battery post. Wiggle the wiring harness where it runs parallel to the valve cover and also near the MAP sensor mounted on the firewall. If you have an 87 or 88 with the C101 connector mounted on the firewall above the brake booster, wiggle it, too.
You want to see as close to 0 ohms of resistance as possible. And when wiggling the harnesses/connectors the resistance value should stay low. If there is a variance in the values when wiggling the wires, you have a poor crimp/connection in the wiring harness or a poor ground at the engine dipstick tube stud. On 87 and 88 models, you could have a poor connection at the C101 connector as well.
Revised 06/12/2012

 

I've got 0.7-0.8 now. I had around that, then I moved the negative wire to another ground stud and it went up to 15 ohms so I sanded / wire-wheeled the areas and it's back to normal.

 

I adjusted the cable at the throttle (gas pedal to throttle). Is there a write up for the throttle to trans?

I like the ground on transmission. I'll have a look at this. I'm thinking it's electrical since in limp mode, it shifts with the shifter. It also usually shifts when cold with the TCU powered up. That's why I'm thinking the speed sensor may not be giving the right information to the TCU and ECU.


Thanks

 

1.2Kohms/1200ohms is correct