Fuel Trim Monitor

This monitor applies to DTCs P0170 and P0173. Following conditions must be met during the test:

• Engine coolant temperature is 176-207°F (80-97°C).
• Atmospheric temperature is 14-140°F (-10-60°C).
• If automatic transmission, selector lever is in "D" range.
• If applicable, overdrive switch is in ON position.
• If applicable, power/economy changeover switch is in POWER position.

Monitor takes about 35 minutes to complete. To run monitor, use illustration. See Fig 1. Perform steps as follows:

1. Start engine.
2. Accelerate to 55-60 MPH.
3. Drive at 55-60 MPH for 30 minutes or more (M/T in 5th gear on non-turbo, or 6th gear on turbo). During this period DO NOT drive at constant speed for more than 120 seconds. Carry out gradual deceleration and acceleration within every 120 second time frame. Depressing brake pedal is okay, but avoid abrupt braking.
4. Return vehicle to shop and turn ignition off.
5. Confirm DTC is not output. If DTC is output, go to appropriate DTC test in appropriate SELF-DIAGNOSTICS article.

Fig 1: Running Fuel Trim Monitor

Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.