tjwalker

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 one 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 other 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 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 four-wire connector clearly embossed with the letters
A,B,C, and D.. For the automatic transmission equipped vehicles the four-wire connector
provides data to the TCU.

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.

cruiser54

Upgraded battery cables like the ones from www.kellyswip.com help a bunch, too.

1990xj2d

awesome thanks for the info ill try that tonight

highmileage

if all else fails check that silly ceramic piece over next to the air box. A chrysler guy once told me that the old jeeps had a problem with hard starts and it was that things fault.

cruiser54

The fuel pump ballast resistor was engineered to provide lower voltage to the fuel pump to reduce the "hissing/whining" noise that customers found objectionable. They can be eliminated/bypassed but be prepared for a louder fuel pump noise. And, if they fail, you get NO fuel pump operation.

1990xj2d

so heres an update the key cycling is not working but if a spray starter fluid or TB cleaner down the throttle body it'll start

cruiser54

Jump the ballast resistor for the fuel pump and see what happens. Don't get your hopes up. I'll bet the fuel pressure is low becuase of bad fuel pump or fuel pump hose in the tank.

highmileage

thank you forgot what that thing was called

DFlintstone

What would be the symptom if the ECU stayed in closed loop? (closed loop is warm/working right?) Might it be lean if the ECU thought it was warm?

1990xj2d

so here an update my fuel pressure is perfect tonight i had to have the jeep towed home for the second time thank you AAA even though i had to get pulled out by a buddies ford sport track but tonight i checked it when i went to start it and i wasnt getting any spark what the hell?and my ground wire on the battery seemed to be hotter than usually possibly from cranking on it ?

tjwalker

If you have NO spark, you MUST concentrate on that .

The top 3 suspects for no spark on the XJ are in this order:

1. Crankshaft position sensor

2. Ignition coil

3. Ignition control module (located below the coil on 87-90 only)

cruiser54

Worst case is the ECU would shoot for 14.7:1 air fuel ratio I guess. Quite unlikely for that to ever happen because it won't do that unless it sees certain things before it will go into closed loop.

OP, not necessarily right now as you are fighting other problems, but I would be adding a ground cable from the firewall to the rearmost bolt on the fuel injection rail and checking how goo a connection you have where your negative battery connects to the block. Remove and clean the connection.

Have you ever checked your CPS for AC voltage on cranking? Better barometer of it's function than the ohms test IMHO.

Remove the coil from the ICU. Clean the contacts between the two and tweak them tighter together. This will make sense when you've got them apart. It's only 2 small torx screws to get them apart bTW.

1990xj2d

cps sensor is good

coil checked out its good

ICM is good

could it be the camshaft position sensor in the distributor? ive been told theres no way to check it but swap it out and whats stupid is i can get a whole new distributor for cheaper than the sensor alone. is it worth getting it since i have to take it out to change the sensor anyways?

DFlintstone

Until the "real guys" show up, I think the disy just orients the injectors. Gotta' ask, is there power at the coil +

Slick761

Cruiser will say no.... guess I agree . Flinstones right it has to do with injector pulse.