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Throttle Position Sensor - Sluggish Engine Response

88amcjeep09

Models


1987-1988 Jeep Models With 4.0L Engine & 1986-1988 Jeep Models With 2.5L Engine


Subject


Fuel Injection System Throttle Position Sensor (TPS) Adjustment Procedures


Index


DRIVEABILITY


Date

October 10, 1988

No.


18-54-88

P-4220 (C18-56)
SYMPTOM/CONDITION

Vehicle may exhibit sluggish response during acceleration and/or have a higher than normal idle speed.


DIAGNOSIS

Perform fuel pressure/volume tests and a thorough visual inspection of all fuel injection and ignition system components. Perform "VEHICLE TEST" and "STATE DISPLAY" tests with the MS 1700 Electronic Diagnostic Tester, paying particular attention to "TPS" (Throttle Position Sensor) status in the State Display mode. If any abnormal readings are encountered, repair as necessary. If TPS adjustments are indicated, perform the following procedures.


REPAIR PROCEDURE

NOTE: REFER TO THE APPROPRIATE WORKSHOP MANUAL (M.R.) AND/OR COMPONENT MANUAL FOR THE PROPER PROCEDURE FOR REPLACING THE TPS IF TESTING INDICATES THAT REPLACEMENT IS NECESSARY. ALL OF THE FOLLOWINF ADJUSTMENT PROCEDURES REQUIRE THE USE OF A VOLTMETER WITH A SENSITIVITY OF AT LEAST 20,000 OHMS/VOLT.

FIGURE 1:




TPS Adjustment Procedure - 4.0L Engine With Manual Transmission


1. Turn the ignition switch to the "ON" position.

2. Do not remove the electrical connector from the TPS. Connect the positive lead of the voltmeter to terminal A and the negative lead to terminal B of the TPS connector (Figure 1). The leads must be inserted through the back of the connector to make contact with the terminals. The terminal identification letters are molded into the connector.
3. with the throttle plate in the closed position, note the "input" voltage. It should be approximately 5.0 volts.

4. Remove the voltmeter positive lead from terminal A and connect it to terminal C. The "output" voltage should be 0.8 volt (16% of input voltage). If this is not the case, continue with this procedure.

5. Adjust output voltage as follows: with the voltmeter leads still attached, carefully loosen the sensor mounting screws and slowly rotate the sensor until the output reading is 0.8 volt with the throttle closed. Then, tighten the sensor mounting screws securely. Be sure not to disturb the sensor's position while tightening the screws. Adjustment is now complete.
TPS Adjustment Procedure - 4.0L Engine With Automatic Transmission


NOTE: THE TPS FOR THE FUEL INJECTION SYSTEM IS INTEGRAL WITH THE TPS FOR THE AUTOMATIC TRANSMISSION. THEREFORE, ADJUSTING THE TPS CORRECTLY FOR THE TRANSMISSION WILL AUTOMATICALLY ADJUST THE "FUEL INJECTION" TPS PROPERLY. THE PREFERRED METHOD FOR ADJUSTING THE TRANSMISSION TPS IS USING THE MS 1700 TESTER IN THE "AUTO TRANS TEST" MODE AND FOLLOWING THE INSTRUCTIONS THAT THE TESTER DISPLAYS. HOWEVER, THE TPS CAN ALSO BE ADJUSTED USING A VOLTMETER AND THE FOLLOWING PROCEDURE.


1. Turn the ignition switch to the "ON" position.

FIGURE 2:




2. There are two wire harness connectors attached to the TPS. Input/output voltage is checked at the SQUARE, FOUR-TERMINAL connector (Figure 2). The terminals are identified by the letters A, B, C, and D molded into the connector.
3. Do not unplug the connector. The voltmeter leads must be inserted through the back of the connector to make contact with the terminals. Connect the positive lead to terminal A and the negative lead to terminal D.

4. With the throttle plate in the closed position, note the "input" voltage. It should be approximately 5.0 volts.

5. Remove the voltmeter positive lead from terminal A and connect it to terminal B. The "output" voltage should be 4.2 volts (82% of input voltage). If this is not the case, continue with this procedure.

6. Adjust output voltage as follows: with the voltmeter leads still attached, carefully loosen the sensor mounting screws and slowly rotate the sensor until the output reading is 4.2 volts with the throttle closed. Then, tighten the sensor mounting screws securely. Be sure not to disturb the sensor's position while tightening the screws. Adjustment is now complete.
TPS Adjustment Procedure - 2.5L Engine With Manual Transmission

1. Turn the ignition switch to the "ON" position.

FIGURE 3:




2. Do not remove the electrical connector from the TPS. Connect the positive lead of the voltmeter to terminal C and the negative lead to terminal B of the TPS connector (Figure 3). The leads must be inserted through the back of the connector to make contact with the terminals. The terminal identification letters are molded into the connector.
3. With the throttle plate held in the wide open throttle (W.O.T.) position, note the "input" voltage. It should be approximately 5.0 volts.

4. Remove the voltmeter positive lead from terminal C and connect it to terminal A. The "output" voltage should be 4.6 to 4.7 volts. If this is not the case, continue with this procedure.

5. Adjust output voltage as follows: with the voltmeter leads still attached, carefully loosen the sensor mounting screws and slowly rotate the sensor until the output reading is 4.6-4.7 volts with the throttle wide open. Then, tighten the sensor mounting screws securely. Be sure not to disturb the sensor's position while tightening the screws. Adjustment is now complete.
TPS Adjustment Procedure - 2.5L Engine With Automatic Transmission


NOTE: THE TPS FOR THE FUEL INJECTION SYSTEM IS INTEGRAL WITH THE TPS FOR THE AUTOMATIC TRANSMISSION. THEREFORE, ADJUSTING THE TPS CORRECTLY FOR THE TRANSMISSION WILL AUTOMATICALLY ADJUST THE "FUEL INJECTION" TPS PROPERLY. THE PREFERRED METHOD FOR ADJUSTING THE TRANSMISSION TPS IS USING THE MS 1700 TESTER IN THE "AUTO TRANS TEST" MODE AND FOLLOWING THE INSTRUCTIONS THAT THE TESTER DISPLAYS. HOWEVER, THE TPS CAN BE ADJUSTED USING A VOLTMETER AND THE FOLLOWING PROCEDURE.


1. Turn the ignition switch to the "ON" position.

FIGURE 4:




2. There are two wire harness connectors attached to the TPS. Input/output voltage is checked at the SQUARE, FOUR-TERMINAL connector (Figure 4). The terminals are identified by the letters A, B, C, and D molded into the connector.
3. Do not unplug the connector. The voltmeter leads must be inserted through the back of the connector to make contact with the terminals. Connect the positive lead to terminal A and the negative lead to terminal D.

4. With the throttle plate in the wide open throttle (W.O.T.) position, note the "input" voltage. It should be approximately 5.0 volts.

5. Remove the voltmeter positive lead from terminal A and connect it to terminal B. The "output" voltage should be 0.2 volts (4% of input voltage). If this is not the case, continue with this procedure.

6. Adjust output voltage as follows: with the voltmeter leads still attached, carefully loosen the sensor mounting screws and slowly rotate the sensor until the output reading is 0.2 volts with the throttle wide open. Then, tighten the sensor mounting screws securely. Be sure not to disturb the sensor's position while tightening the screws. Adjustment is now complete.
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