Test Ha - Fuel Control
To prevent replacement of good components, inspect all related wiring, wiring harness, connectors and components for evidence of overheating, looseness and other visible damage. Visually inspect intake air cleaner, duct, fuel delivery system for leaks or severe wear.
- EGO Sensor Sensitivity Test: This test is for vehicles built after 11/2/87. On all others, proceed to next step. With STAR tester adapter connected to STO and ground (STI open), start engine and run until operating temperature is reached. Increase engine speed to 2500 RPM. If the monitor light flashes 8 times in 10 seconds, proceed to step 4). If monitor light does not flash 8 times in 10 seconds, proceed to next step.
- Check EGO Sensor Output: Warm engine and allow to idle. Unplug EGO sensor. Using DVOM on 5-volt scale, measure voltage between EGO sensor connector (sensor side) and ground. Raise engine speed to 4000-4500 RPM until voltmeter indicates 0.7 volts. Decrease and increase engine RPM rapidly and note voltmeter reading. At 1000-2500 RPM, reading should be 0-0.4 volts. At 3000-4500 RPM, reading should be 0.5-1.0 volts. If readings are within specification, proceed to next step. If readings are not within specification, proceed to TEST HE .
- Check EGO Switching Voltage: With EGO sensor connected and breakout box installed, start engine and bring to operating temperature. Using DVOM on 5-volt scale, measure voltage between pins No. 29 and 40. Decrease and increase engine RPM rapidly and note voltmeter reading. At 1000-2500 RPM, reading should be 0-0.4 volts. At 3000-4500 RPM, reading should be 0.5-1.0 volts. If readings are within specification, proceed to next step. If readings are not within specification, proceed to TEST HE .
- Injector Drive Signal Check: Install breakout box and connect standard 12-volt non-power test light between pins No. 58 and 37. Crank or start engine and note test light. Repeat test between pins No. 37 and 59. If test light glows dim on both tests, proceed to step 7). If test light does not illuminate on one or both tests, proceed to next step. If test light illuminates brightly on one or both tests, proceed to step 6).
- ECA Power Test: Install breakout box and unplug ECA. Turn ignition on. Using DVOM on 20-volt scale, measure voltage between pins No. 1 and 40, and between pins No. 37 and 40. If readings are greater than 10 volts, replace ECA. If readings are 10 volts or less, proceed to TEST FC .
- Injector Circuit Check For Shorts: Unplug ECA and disconnect battery. Install breakout box. Using DVOM on 200,000-ohm scale, measure resistance between pins No. 59 and 37, 20, 40, 1 and 49. Repeat test between pins No. 58 and 37, 20, 40, 1 and 49. If any of the readings are less than 10,000 ohms, check for shorts to ground or VPRW in related harness. If any of the readings are 10,000 ohms or more, replace ECA.
- Injector Balance Test: Unplug ISC connector. Start and run engine at 2000 RPM. Unplug and plug in injectors one at a time while noting RPM drop for each injector. Plug in ISC. If each injector produced at least 150 RPM drop, proceed to next step. If each injector did not produce at least 150 RPM drop, repair circuit of injector in question. On vehicles built before 11/2/87, confirm operation of solenoid resistor in fuel delivery system. If operation is okay, replace faulty injector.
- Deceleration Fuel Cut-Off Test: Install breakout box and plug in ECA. Connect standard non-powered 12-volt test light between pins No. 58 and 37. Start engine and allow to idle. Increase and decrease engine speed between idle and 4000 RPM and note test light. During idle, test light should flash. During deceleration (2000-4000 RPM range), test light should not illuminate. Repeat test between pins No. 59 and 37. If test light responds as described, diagnose for mechanical problem. If test light does not respond as described, replace ECA.