xjmercenary90

Hey all. A few problems i need suggestions on. So on the 90 xj I just bought the guy said he "just replaced tranny with a newer one" couldn't prove with paperwork so doubtful. Anyways, while driving at freeway speed my tranny keeps shifting in and outta gears, I'm not moving my foot and it happens on flat land is there an adjustment needed in downshift cable? Does it have a downshift cable? Lol. Also my speedo bounces and is off by 6+ mph how do I adjust that. Another problem I am having is a howl now and then from rear end while coasting only ( just let off throttle) I plan on an 8.8 swap at some point and when I do what ratio do you guys suggest? I have 33-12.5 it will be mainly street and some off road.

Thanxs in advance

cruiser54

Not a downshift cable, but adjust it anyway.
https://www.cherokeeforum.com/f2/free-quick-fix-41821/


Trans switch on dash in Comfort positon?

Could be a TPS that's faulty on the "trans" side.

Bad grounds at the engine dipstick tube stud affect the "trans shift logic" circuit of the trans computer.

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, failed emission tests, and wasted money replacing components unnecessarily.
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.
For those of us with Comanches, it’s very important to remove the driver’s side taillamp assembly to access the ground for the fuel pump. Remove the screw holding the black ground wire. Scrape the paint from the body and corrosion from the wire terminal. Reattach securely.
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 03-04-2013

Radi

I think you still have a speedo cable, they bounce when they get dry. A bit of graphite dry lube works well.
Speedo off- what size tires are you running?

jdjonesdr

OK, I'm a little stumped on this one. Can you tell me the "official" name for this cable? If I understand correctly, it's a Throttle Valve Cable?

I'm searching on partsgeek and rockauto and can't seem to find it.

The one I have is not in any shape to be adjusted.

xjmercenary90

I tried that cable trick. No change. This weekend im going to redo all the grounds, hope its as easy as that.

I am running 33/12.50/15

cruiser54

TV/throttle valve cable. Increases fluid pressure in the trans the wider open the throttle is.

cruiser54

ALWAYS a good idea to do the ground refreshing and trans plug refreshing.

Switch in Power or Comfort?

If in Power, does it light up?

jdjonesdr

Thanks Cruiser,

Out of curiosity, do you know of anywhere that it can still be purchased, or is this another of those "nobody has them anymore" parts, and I should chase down a used one?

Mine has deteriorated to the point where it can no longer be adjusted, and I know it needs adjusting.

My truck runs fine on the open road, but in city driving, it frequently changes gears up and down trying to find which is best.

Hitting the "power button" does help considerably, but at the expense of less MPG.

As part of my "restoring it back to stock" project, I'd like to see that fixed as well.

Thanks again for your efforts on the board.

cruiser54

Don't know if they're still available from the dealer or not.

A used one wuldn't bither me. The only thing I've ever seen break or wear is that connection where it adjusts. That could be jury rigged if needed.

Actually, the Power setting should not affect MPGs at all. The factory eliminated the switch in 91 or so, mostly due to customer complaints of habits you describe from customers when using the Comfort mode.

cruiser54

Be sure to do the ground refreshing and trans plug refreshing. If you read the intro to the ground refreshing, you'll see why.

And you just made me think of something. I came up with the trans plug refreshing after trying it on my wife's 88 when it was shifting weird. That's what fixed it. Not one whole cup of coffee yet!!!

cruiser54

Check this out:

https://www.cherokeeforum.com/f2/int...issues-165336/

jdjonesdr

Thanks, Big guy.

I'm pretty confident that my problem(if you can call it that) is the inability to adjust the cable, since the button is severely deteriorated. The cable has some slack in it. not much, but when it's properly adjusted, it shouldn't have any slack at all, if I've read all the posts about it correctly.

I've already changed most of the sensors under the hood. Pretty sure the cable is the only thing I still need to change.

If anybody out there has a used throttle valve cable in excellent condition they want to sell, give me a hollar.

XJ_will

Mine kind of does the same except its on city streets around 45mph. it will want to jump from 3 to 4th when I let off the gas then when I press back on the gas. always in comfort mode. On the highway no problem 73mph at 2000 rpm. I did notice in power mode that it wont do that it will just stay in 3rd at city speed limits again 45 mph.

XJ_will

My speedo cable went out also, but it did that when it was working 4 months ago.

XJ_will

But now after reading Cruisers info im just going to adjust that TV cable