Mode I and II (Mixture Ratio Feedback Control)

NOTE: Air/fuel mixture is not adjustable. The following procedure will describe inspection of the mixture ratio feedback system.

1. Start the engine and warm it up until the water temperature indicator points to the middle of the gauge.
2. Operate the engine at 2000 rpm for 2 minutes under no load.

Fig. 55 Inspecting E.C.U. Lamps:

3. Make sure that the green L.E.D. on the Engine Control Module (ECM) (located on the floor board in front of the center console) flashes on and off more than 5 times in 10 seconds at 2000 rpm under no load.
a. If OK proceed to step 4. The Oxygen (O2) sensor is operating properly.
b. If not OK, Refer To OXYGEN SENSOR TESTING AND INSPECTION Testing and Inspection
4. Race the engine 2 or 3 times, then idle.

Switching Diagnostics Modes:

5. Turn the diagnostic mode selector on the ECM fully clockwise and wait for the L.E.D.`s to flash 2 times, then immediately turn the selector counterclockwise. The ECCS system is now in "Mode 2".

TECH TIP: Remember to turn the mode selector screw back (counterclockwise) right after you see the diodes flash two times. If you wait too long, the self-diagnostics will have moved on to mode 3.

6. Run the engine at 2000 rpm under no load and make sure that both L.E.D.'s are flashing at EXACTLY the same time.
a. If OK, air/fuel mixture is correct. Proceed to step 7 and END TEST.
b. If not OK, Refer to Idle Speed/Ignition Timing/Idle Mixture Ratio Inspection Idle Speed/Ignition Timing/Idle Mixture Ratio Inspection

7. Turning the engine off will return the ECCS system to "Mode 1" (normal operating mode).