sansocal

My xj is starting to act out again. When im driving, in any gear, around 1500-2000 rpm it will buck/lurch/stutter/jump i dont know the best way to say it. It will just feel like its giving up for a split second than be fine, then repeat. It usually only happens when the gas is barely on. In between pulling and coasting.

-Doesnt do it at a stop revving with brakes on
-doesnt do it in neutral
-doesnt do it in park
- tranny fluid is fine (red and in the hash marks)
- tps is newer
-continues to have issues when the TCM fuse is out and shifting manually
-most noticable in 3rd, going up a hill underload
-wont buck if you give it more gas (lugg the engine down)



I swear its a tranny problem but i have such limited knowledge of the issue it is hard to make assumptions. any ideas on how to start troubleshooting?

sansocal

any thoughts about where to start on this?

jomps

what year & any cel. any recent tune ups...

cranesrule

Throttle position sensor. Even if it is fairly new, it is taking a dump again.

BillyBoy

"Search bar" the TPS. Throttle Position Sensor.

There are about 1000 write ups on it.

BillyBoy

Read the post...

"Long Crank Period"

Cruiser54 has a nice write up about grounds on the dipstick holder. Might be something as easy and cheap as that, and a good place to start. Sounds like the guy knows his stuff too, so you might want to even PM {private message} him.

lgnut123

My 97 does the exact same thing. It will kick if theres somewhat of a load at low rpms like it should downshift but hasnt quite got there yet. But if you accelerate enough to make it downshift then its fine. Right?

cranesrule

Also a symptom that a **** tps can produce. And his other symptoms have tps written all over them.

sansocal

thats exactly whats going on.

I never thought about testing the engine side of the tps yet, i tested the tranny side its fine. I wouldnt be surprised if its broken again its the 3rd one i got from oreillys (BWD brand). if its done again im going to napa.

also cruiser helped me last time the tps was bad, i redid all the grounds and adjusted the tps per his instructions.

ill check it tomorrow and post back.

sansocal

1989, do 89s even have cels? lol any way i can test to make sure the bulb isnt burnt out?

cranesrule

Yes they have one. Tps will not always throw it though.

HawK_Racing

Hey guys I've having the exact same problem with my 88 XJ. any reports if the TPS was the problem?

sansocal

I checked out the tps and it was fine, I adjusted it again but no change.

cruiser54

Renix has no CELs.

cruiser54

Only one way to find out on yours. Check it:

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