MERCURY 2.5 LITER THROTTLE POSITION SENSOR (TPS) ADJUSTMENT

1. Disconnect TPS from EFI harness on starboard side of intake manifold.
2. Connect digital multimeter using TPS Test Lead Assembly between TPS connector and ECU harness connector. Setmeter to read DC volts.
3. Disconnect TAN/BLACK engine head temperature sensor leads located on port cylinder head.
4. Turn key to the ON position.
5. Ensure throttle position is at idle.
6. Check TPS setting for a value of .200 - .300 volts DC. If voltage is out of tolerance proceed to step 7. If voltage is within tolerance proceed to step 10.
7. Loosen screws securing TPS to manifold.

8. Rotate TPS either clockwise or counter-clockwise to obtain readout of .240 - .260. NOTE! It is very touchy and will change dramatically with just the slightest movement.
9. Tighten TPS screws holding the TPS firmly to ensure correct tolerance.
10. Slowly move throttle lever to full open position while monitoring voltage reading. Voltage reading should increase and decrease smoothly. Maximum voltage reading at full throttle is approximately 7.46 volts. Ensure that idle reading returns to a tolerance of .200 - .300 volts.
11. Remove test lead and reconnect TPS harness to ECU harness.
12. Reconnect TAN/BLACK engine head temperature sensor leads located on port cylinder head.

NOTE: If engine appears to run too rich or too lean, the TPS can be readjusted. Decreasing voltage yields a leaner mixture. Increasing voltage yields a richer mixture. Allowable TPS range: .200 - .300 volts.

NOTE: The Digital Diagnostic Terminal (DDT) can be used to determine whether the TPS is set within the recommended operating range of 0.200 - 0.300 volts. However, it is recommended that the DDT not be used to make adjustments of the TPS. Due to the circuitry characteristics of the ECM, the DDT is not able to always display accurately small TPS movements. A digital voltmeter should be used when making adjustments to the TPS.