See Figures 1 through 5
Because of ECU control, no periodic service adjustments are necessary. However, if timing or idle speed problems are suspected a combined ignition timing and idle speed inspection procedure is provided.
The following procedure should only be used as part of the timing and idle speed inspection found on the flow charts at the end of the section. No periodic idle speed adjustments should be required by these vehicles. ALSO, always refer to the instructions or specifications found on the Vehicle Emission Control Information (VECI) label found underhood for additional or updated information which is applicable to your particular vehicle.
- Turn off the: headlights, heater blower, air conditioning, and rear window defogger. If the truck has power steering, make sure the wheels are in the straight ahead position. The ignition timing must be correct to get an effective idle speed adjustment. Connect a tachometer (a special adapter harness may be needed, SST# EG11170000) according to the instrument manufacturer's directions.
- Start the engine and warm the engine so it reaches normal operating temperature. The water temperature indicator should be in the middle of the gauge.
- Run engine at 2000 rpm for about 2 minutes under no load.
- Race the engine to 2000-3000 rpm a few times under no load and then allow it to return to idle speed.
- Apply the parking brake securely. If equipped with an automatic, put the transmission into D .
- Adjust the idle speed to the figure shown in the Tune-Up Specifications Chart by turning the idle speed adjusting screw.
- Turn the engine OFF and remove the tachometer. Road test for proper operation.