Odd question

Hey guys, hoping someone has a simple answer for my question. I just picked up a 90 XJ (4.0/auto/4wd) after some searching the stumble i'm experiencing seems to be caused by the TPS, now since it only cost about 40 bucks i figured why not just slap a new one on there. that's when I discovered someone has cut off the connectors from the engine harness and directly spliced the TPS to it :twak: so on my next day off I plan to run down to Junkyard and grab a new harness and connectors to repair it properly is there a certain range of years or anything particular as to what to look for and do the colors of the wires match? appreciate any input and just trying to avoid further headaches. thanks

what r ur symptoms? cause i just replaced mine and thought it was gonna cure it but it didnt

when your just barely on the throttle it want's to spit and sputter regardless of speed and gear, it's really annoying from a stop, if you don't give it an moderate amount of gas it will either a: want to stutter then die or b:stutter then take off rather abruptly.

all in all it's not *that* bad but i drive like an old man and am barely on the throttle most of the time.

BTW thanks for the reply!

fuel pump?

hmmm, I'll dig out the gauge and check on that.

Sounds consistant with TPS.

You need to look for an '87 to '90 XJ with auto tranny. If you want the entire harness, stick with '89 and '90.

Also, you don't just slap on a TPS, it needs to be set.

Happy hunting!

no, i'd much rather splice on the connectors rather than swap an entire harness, so the 87-90 should have the same color coding as well?

Edit: forgot to mention I have the procedure bookmarked for the TPS adjustment. but appreciate the heads up

Just put new GM weather pack connectors on the harness end. Problem solved.

http://motors.shop.ebay.com/i.html?...ect&_osacat=0&bkBtn=&_trksid=p4506.m270.l1313

http://www.weatherpackkits.com/?gclid=CLu1tIGVvK4CFcjc4AodykcqQA

http://crimpsupply.com/packard-delphi/weather-pack?gclid=CM7eyP-UvK4CFUdN4AodZDiRWw

Here's how to adjust it. Be sure to solder and shrink tube the connections.
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: 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.
If you see more than 1 ohm of 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 11-28-2011

By the way, I should add that when I was fooling with my 87 (4.0, AW4), I found that too high an output voltage on the tranny section would contribute to the off-idle burp and stumble. If you're going to err, do so toward a slightly lower output voltage.

WOW! thanks for all the replies guys!:worship:

Found the proper harness off an 89 at the yard today, got it spliced on and the TPS adjusted to spec and the idle was stupid high. PO must of cranked it up to offset the poor adjustment. some fiddling and time later and all is well. however the screws that hold it in place started to strip (the head not the threads) i'll have to swap them out with some allen screws to prevent that from happening again.

btw do the 90's have fan shrouds? Every single XJ I saw in the yard had no shroud and mine doesn't as well.

Yes, they had shrouds.

What fiddling was necessary to get the idle correct?

ah, that's what I figured. now to find one....

and I had to back off the idle screw then re-adjust the tps for the new position of the throttle.

So you backed off the allen head throttle stop screw until the butterfly was fully closed and then went tighter til the butterfly barely moved?

As I recall, the butterfly should close almost all the way, with a gap about the thickness of a piece of paper. It's not supposed to be adjusted at all, so there's little in the way of specs for putting it back if someone else messed it up.

well as the screw heads started to strip i decided that was enough of that so i got it pretty darn close and adjusted the idle screw for 1k in park and 750ish rpms in drive. i have no issues now and shift points are spot on so it will do for now.

going to get in there and clean everything and set it when the rain stops.

It should close all the way and you tighten the screw in until the faintest movement is seen. All idle air needs to go through the idle air bypass and IAC. The screw just keeps the butterfly from gouging into the soft bore of the TB.

well i adjusted the butterfly to just barely open and the tps per the instuctions you posted and idle is bavk up to almost 3grand. adjusted the idle screw all the way out and its still way high...

Has anyone tampered with the idle air screw that has a Torx head on the driver's side of the throttle body?

cruiser54 said:

Has anyone tampered with the idle air screw that has a Torx head on the driver's side of the throttle body?

Click to expand...

I had one that had been tampered with, but it didn't seem to make much difference. As it happened, my throttle body was badly worn anyway, so I solved the problem by replacing it. I'd leave it alone, since there seem to be no instructions on how to "un-tamper" it.