89 renix xj high idle with tps adjusted
#1
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Year: 1989
Model: Cherokee (XJ)
Engine: 4.7
89 renix xj high idle with tps adjusted
Hey guys I've just went out and bought a new throttle position sensor after fighting a no start that ended up being the computer. Problems I've been having
1. Jeep has a horrible time taking off if under hard acceleration.
2. If tps on ecu side is adjusted to 17% it revs at about 2,000 rpm and will only go up if I hit the throttle.
3. Does this weird idle drop when engine braking
4. No power till 3k rpms then takes off like a rocket
At this point I'm lost any help would be appreciated.
Build
4.7 stroker "cold air" and 4hole 22lbs injectors
1. Jeep has a horrible time taking off if under hard acceleration.
2. If tps on ecu side is adjusted to 17% it revs at about 2,000 rpm and will only go up if I hit the throttle.
3. Does this weird idle drop when engine braking
4. No power till 3k rpms then takes off like a rocket
At this point I'm lost any help would be appreciated.
Build
4.7 stroker "cold air" and 4hole 22lbs injectors
#2
CF Veteran
One common thing that can happen is a intake manifold being loose or not sealed right. Did you use a quality gasket when you put it back together? Torque all the bolts to the right spec with the correct steps.
#3
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Year: 1989
Model: Cherokee (XJ)
Engine: 4.7
Yes I believe it was all felpro but I cant remember I have tried starting fluid around all the gaskets for intake and what not and no rev so I think that's all sealed up
#4
CF Veteran
Mine is all stock engine, '88 with 250k and I too get a high rev from time to time, on random though. I haven't sprayed around the manifolds yet.
#6
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Year: 1990
Model: Cherokee (XJ)
Engine: 4.0
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#8
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Year: 1990
Model: Cherokee (XJ)
Engine: 4.0
try setting it a bit lower.
#10
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Year: 1990
Model: Cherokee (XJ)
Engine: 4.0
2 possibilities.
1-You're probing the trans side of the connector which never works well for idle speed issues.
2-you're probing the engine side of the TPS and using the trans side values as a target.
RENIX TPS ADJUSTMENT
Before attempting to adjust your TPS, there are a few things that need to be done.
- 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.
- With the KEY OFF, and using the positive (red) lead of your ohmmeter, set on the lowest scale, 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 parallels the valve cover and also over near the MAP sensor on the firewall.
TPS ADJUSTMENT FOR ENGINE ISSUES
Both Renix manual and automatic transmission equipped XJs and MJs have a flat three-wire connector to the TPS which provides data input to the ECU. The three wires in the connector are clearly embossed with the letters A, B, and C. Wire “A” is positive. Wire “B” is ground. DO NOT UNPLUG THE CONNECTORS!
- 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.
- Loosen both T-20 Torx screws attaching the TPS to the throttle body and rotate the TPS until you have achieved your desired output voltage.
- Tighten the screws carefully while watching to see that your output voltage remains where it is supposed to be. If you can’t achieve the correct output voltage, replace the TPS and start over.
TPS ADJUSTMENT FOR AUTOMATIC TRANSMISSION ISSUES
Renix automatic transmission-equipped XJs and MJs 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 outlined above—FOR ALL 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. THIS SQUARE FOUR WIRE CONNECTOR IS USED FOR TRANSMISSION/SHIFTING RELATED ISSUES ONLY.
First off, DO NOT UNPLUG THE CONNECTORS!
- KEY ON, measure voltage between “A” positive and “D” ground by back-probing the connector. 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.
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. The square 4 wire connector is just not used.
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