cherokeelaredo'90

In my 1990 my aw4 has recently been wanting to hold gears for awhile, I'll put it in the power mod and then it'll rev up to around 2700ish and won't shift unless I punch the throttle or turn it back to comfort. I'm not sure if this is "normal" or if I'm just paranoid..??

ZINGGG

In a situation like this, the first thing you should do is adjust your throttle valve cable. To do this:
1. Shift transmission into park and shut engine off.
2. Press cable release button
3. Push cable conduit back into cable adjuster body as far as possible
4. Rotate throttle body lever to wide open throttle position. Cable will ratchet to correct adjustment point as lever is rotated.

See if doing this will make a difference! And the procedure takes you literally 15 seconds to do.

cherokeelaredo'90

By cable release button.. Is that on the throttle body?
And thanks for the advice, I'll try it out tomorrow

ZINGGG

Yes, the cable on the throttle body. Here's a couple pictures to help you out

janepaul

that's a nice stuff it would help me a lot thanks for the post.*

cruiser54

Great place to start. If that doesn't fix it, you'll need to test the TPS on the "trans side". Got a voltmeter?

cherokeelaredo'90

okay I pressed the button and pushed the conduit all the way back in. And then, with the button still depressed, I pushed the throttle all the way to wot. When I did this the conduit carried all the way out? does this mean it's time for a new cable? And also just by curiosity where these cables go/ come from. I know one side is attached to the throttle pedal, but where does the other side go?

cherokeelaredo'90

I guess it won't hurt to test it out anyways? How do you go about checking it on the trans side, I looked up how to check the actual tps, but how do you do the trans side?

cruiser54

RENIX TPS ADJUSTMENT
Before attempting to adjust your TPS be sure the throttle body has been recently cleaned.
It's especially important that the edges of the throttle butterfly are free of any carbon build-up.
IMPORTANT NOTE: Set your meter to measure Ohms. 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.
If you see more than 1 ohm of resistance, and/or fluctuating resistance, some modifications to the sensor ground harness will be
necessary. The harness repair must be performed before proceeding.
I can provide an instruction sheet for that if needed.
MANUAL TRANSMISSION:
RENIX manual transmission equipped XJs have a three-wire TPS mounted on the throttle body.
This manual transmission vehicle TPS provides data input to the ECU. The manual transmission
TPS has three wires in the connector and they're clearly embossed with the letters A,B, and C.
Wire "A" is positive.
Wire "B" is ground.
Key ON, measure voltage from "A" positive to "B" ground by back-probing the connectors..
Note the voltage reading--this is your REFERENCE voltage.
Key ON, back-probe the connector at wires "B" and "C". Measure the voltage. This is your
OUTPUT voltage.
Your OUTPUT voltage needs to be seventeen percent of your REFERENCE voltage. For
example: 4.82 volts X .17=.82 volts. Adjust the TPS until you have achieved this percentage. If
you can't achieve the correct output voltage replace the TPS and start over.
AUTOMATIC TRANSMISSION:
RENIX automatic transmission equipped XJs have a TPS with two connectors. There is a flat three-
wire connector, same as the manual transmission vehicles have, and it is tested the same as the
manual transmission equipped vehicles--FOR ENGINE MANAGEMENT RELATED ISSUES.
However, the automatic TPS also has a square four-wire connector clearly embossed with the letters
A,B,C, and D. It only uses three wires and provides information to the Transmission Control Module.
Key ON, measure voltage between "A" positive and "D" ground. Note the voltage. This is your
REFERENCE voltage.
Back-probe the connector at wires "B" and "D". Measure the voltage. This is your OUTPUT
voltage. Your OUTPUT voltage needs to be eighty-three percent of your REFERENCE voltage.
For example 4.8 volts X .83=3.98 volts. Adjust the TPS until you have achieved this percentage.
If you can't, replace the TPS and start over.
So, if you have an automatic equipped XJ your TPS has two sides--one side feeds the ECU, and
the other side feeds the TCU. If you have TRANSMISSION issues check the four-wire
connector side of the TPS. If you have ENGINE issues check the three-wire connector side of
the TPS.
For those with a MANUAL TRANSMISSION--the TPS for the manual transmission XJs is
stupid expensive. You can substitute the automatic transmission TPS which is reasonably priced.
Revised 03-13-2012

cherokeelaredo'90

Thanks for that write up, right now I sadly can't do anything cause it just started to rain. I'll have to wait till later..

cherokeelaredo'90

Alright I finally got some free time to work on the jeep. I got the tps enginge side adjusted perfectly and then I went to the tranny side and that was out so I adjusted that perfectly. I then went back to the engine side which was now slightly out. I feel like this may be normal, but on better news the jeep shifts more smoothly
I have another question, what's the optimum rpm level to cruise at? I've heard around 2100-2800 but that was for a manual.. Would it be the same for a auto? Thanks!

cruiser54

You'll never get them both perfect.

cherokeelaredo'90

Alright I drove it for a lot longer than I usually do and the jeep is still revving out and not shifting unless I punch.
Okay, here's the story. I was in some stop and go traffic for awhile so my jeep was getting pretty hot, the fan kept coming on so it was over 210*. I had the power switch on and every time I'd accelerate it would rev up to just below 3k and not shift unless I punched it. After awhile of being slightly annoyed I turned the power button off, it began to shift smoothly again. After awhile with it in comfort it would begin to hold the gear and not shift unless I punched it
I'm beginning to it may be the ecm going out. (I think that's the name for the aw4 computer). Does this sound like it may be the case? And if so, are all aw4 ecm's the same. ie a ecm frommmm a 96 can be used in my 90's aw4? Any help is appreciated!!

cruiser54

TCU is what it's called.

Do this first. Over by the trans dipstick tube are two kinda large connectors. One is gray, the other black. Unplug them, inspect the pins, spray them out with contact cleaner and plug them back together. See if that helps. Those two plugs are the info superhighway between TCU, TPS and trans solenoids.

Another thing to do on EVERY Renix Jeep once in it's lifetime is a good ground refreshing. Notice that one circuit that grounds on the Engine dipstick tube stud is "TCU shift point logic". Here's how:

Renix Ground Refreshing
The Renix era XJs and MJs were built with an under-engineered grounding system for the engine/transmission electronics. One problem in particular involves the multiple ground connection at the engine dipstick tube stud. A poor ground here can cause a multitude of driveabililty issues, wasted time, and wasted money replacing unnecessary components.
The components grounding at the dipstick tube stud are:
Distributor Sync Sensor, TCU main ground, TCU "Shift Point Logic", Ignition control Module, Injectors, ECU main ground which other engine sensors ground through, Oxygen sensor, Knock Sensor, Cruise Control, and Transmission Sync signal. All extremely important stuff.
The factory was aware of the issues with this ground point and addressed it by suggesting the following:
Remove the nut holding the wire terminals to the stud. Verify that the stud is indeed tightened securely into the block. Scrape any and all paint from the stud’s mounting surface where the wires will attach. Must be clean, shiny and free of any oil, grease, or paint.
Inspect the wire terminals. Check to see that none of the terminals are crimped over wire insulation instead of bare wire. Be sure the crimps are tight. It wouldn’t hurt to re-crimp them just as a matter of course. Sand and polish the wire terminals until clean and shiny on both sides. Reinstall all the wires to the stud and tighten the nut down securely.
While you’re in that general area, locate the battery negative cable which is fastened to the engine block just forward of the dipstick stud. Remove the bolt, scrape the block to bare metal, clean and polish the cable terminal, and reattach securely.
Another area where the grounding system on Renix era Jeeps was lacking is the engine to chassis ground. There is a braided cable from the back of the cylinder head that also attaches to the driver’s side of the firewall. This cable is undersized for it’s intended use and subject to corrosion and poor connections at each end.
First off, remove the cable end from the firewall using a 15mm wrench or socket. Scrape the paint off down to bare metal and clean the wire terminal. Reattach securely.
Remove the other end of the cable from the rear of the head using a 3’4" socket. Clean all the oil, paint and crud from the stud. Clean the wire terminal of the cable and reattach securely.
A suggestion regarding the braided cable:
I prefer to add a #4 Gauge cable from the firewall to a bolt on the rear of the intake manifold, either to a heat shield bolt or fuel rail bolt. A cable about 18" long with a 3/8" lug on each end works great and you can get one at any parts store already made up. Napa has them as part number 781116.
A further improvement to the grounding system can be made using a #4 cable, about 10" long with 3/8" terminals at each end. Attach one end of this cable to the negative battery bolt and the other end under the closest 10mm headed bolt on the radiator support just forward of the battery. Napa part number 781115.
　
　
If you want to upgrade your grounds and battery cables in general, contact Jon at www.kelleyswip.com. He makes an incredible cable upgrade for a very reasonable price.
　
Revised 11-28-2011

cherokeelaredo'90

Wow thanks for all the help, I'll be checking all that stuff out as soon as i have time. Thanks again