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Test P - Fuel Control Test

NOTE: Fuel contaminated engine oil may affect 41 and 42 service codes. If this is suspected, remove PCV from valve cover and repeat Quick Test. If problem corrected, change engine oil and filter.
  1. Start and run engine for 2 minutes at 2000 RPM. With engine at normal operating temperature, perform Engine Running Self-Test. If code 43 present, go to next step. If no code 43, repair all other codes as described in Engine Running Self-Test.
  2. Check for exhaust leaks at exhaust manifold and inlet pipe. Repair as required and repeat Quick Test. If no leaks, go to next step.
  3. Code 43. Start engine and allow to idle. If engine idle deteriorates and remains poor during and after Engine Running Self-Test, service fuel system. If not, replace oxygen sensor and repeat Quick Test.
  4. Code 41. Turn ignition off and place DVOM on 20 volt scale. Disconnect harness at oxygen sensor and connect DVOM between oxygen sensor and engine ground. Start and run engine 2000 RPM for 2 minutes. If reading is greater than .5 volt at end of 2 minutes, go to next step. If not, replace oxygen sensor and repeat Quick Test.
  5. Turn ignition off and wait 10 seconds. Disconnect harness at oxygen sensor. Disconnect 60-pin connector at ECA and inspect. Repair as required. Connect breakout box and leave ECA disconnected. With DVOM on 2000 ohm scale, measure continuity from box pin 29 to oxygen sensor connector. Then measure from box pin 49 to pins 40 and 60. If both readings less than 5 ohms, go to next step. If either reading 5 ohms or more, repair open circuit and repeat Quick Test.
  6. Turn ignition off. Breakout box installed and ECA and oxygen sensor disconnected. With DVOM on 200,000 ohm scale, measure resistance between box pins 29 and 49. If reading is 10,000 ohms or more, oxygen sensor input circuit is okay, go to step 10). If reading is less than 10,000 ohms, repair cause of resistance to ground and repeat Quick Test.
  7. Turn ignition off. Disconnect breakout box and reconnect ECA. Disconnect harness at oxygen sensor. Using jumper wire, jumper oxygen sensor circuit at sensor harness to engine block. Perform Engine Running Self-Test. Remove jumper wire at end of test. If code 41 present, go to step 9). If no code 41, go to next step.
  8. Turn ignition off and wait 10 seconds. Oxygen sensor disconnected. Disconnect 60-pin connector at ECA and inspect. Repair as required. Connect breakout box and leave ECA disconnected. With DVOM on 2000 ohm scale, measure continuity from box pin 29 to oxygen sensor connector. Then measure from box pin 49 to oxygen sensor ground on engine. If both readings less than 5 ohms, check ECA harness connectors for damage and replace ECA if any terminals found defective. If either reading 5 ohms or more, repair open circuit and repeat Quick Test.
  9. Turn ignition off. Breakout box and oxygen sensor disconnected and ECA connected. Disconnect PCV hose at intake manifold. With DVOM on 20 volt scale, connect leads between oxygen sensor and engine ground. Start and run engine at 2000 RPM for 2 minutes and observe DVOM. If reading less than .4 volt, oxygen sensor okay, go to next step. If reading .4 volt or more, replace oxygen sensor and retest.
  10. Install fuel pressure gauge. Start and run engine and observe pressure. If pressure is 24-45 psi (1.7-3.2 kg/cm2 ) with engine running or 60 seconds after final ignition off, go to next step. If pressure is not within specifications, check electric fuel pump(s).
  11. Turn ignition off. Disconnect 60-pin connector at ECA and inspect. Repair as required. With DVOM on 200 ohm scale, connect leads from box pin 57 to pin 58, then from box pin 57 to pin 59. If reading less than 1.5 ohms or greater than 3.5 ohms, repair harness at suspect injector. If harness okay, replace injector. If reading 1.5-3.5 ohms, go to next step.
  12. Turn ignition off and wait 10 seconds. Connect breakout box and reconnect ECA. Using a non-powered 12 volt test lamp, connect test lamp from box pin 57 to pin 59. Crank or start engine. Repeat test with test lamp connected from box pin 57 to pin 58. If test lamp glows dimly on both tests, system normal, go to next step. If test lamp does not glow on 1 or both tests, ensure 12 volt battery power at box pin 57. If okay, replace ECA. If test lamp glows brightly on 1 or both tests, repair short to ground in both injector circuits. If okay, replace ECA.
  13. Turn ignition off and wait 10 seconds. Disconnect breakout box and reconnect ECA. Connect tachometer to engine. Start and run engine at 2000 RPM. It may be necessary to disconnect throttle kicker solenoid and use throttle body stop screw to set engine speed. Disconnect and reconnect injectors 1 at a time and note RPM drop for each injector. Reset curb idle speed and reconnect throttle kicker (if disconnected). If each injector produced at least 100 RPM drop, fuel system is okay, check for air/vacuum leak, fuel contamination and faulty EGR system. If each injector did not produce 100 RPM drop, replace suspect injector.
Fig 1: Throttle Body Wiring Diagram
G9197
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