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Home >> Volvo >> 1998 >> V70 Base, Standard >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Tests W/Codes >> Diagnostic Tests >> DTC P0170/EFI 231-EFI 232, DTC P0171/EFI 231-EFI 232 & DTC P0172/EFI 231-EFI 232 >> Diagnosis (Upper Limit)

Diagnosis (Upper Limit)

  1. Check for other DTCs. If DTC P0440/EFI 315 is stored, perform testing on that DTC first. If DTC 315 is not stored, go to next step.
  2. Turn ignition on, with engine off. Ignition off. Connect mass air flow (MAF) sensor. Turn ignition on. Connect a voltmeter between Mass Air Flow (MAF) sensor connector terminals 2 and 4. The voltmeter should display 0.1-0.2 volt. If voltage is 0.1-0.2 volt, go to step  3. If voltage is not 0.1-0.2 volt, retest using new MAF sensor.
  3. Check air leakage in the intake system. See AIR INDUCTION SYSTEMS in SYSTEM/COMPONENT TESTS article. If there are no intake air leaks, go to step  4. If there any intake air leaks, repair as necessary. After repairs, erase any stored DTCs.
  4. Check for air leakage in the exhaust system. See EXHAUST SYSTEM in SYSTEM/COMPONENT TESTS article. If there are no exhaust air leaks, go to step  5. If there are any exhaust air leaks, repair as necessary. After repairs, erase any stored DTCs.
  5. Check fuel pressure and residual fuel pressure. See FUEL SYSTEM in BASIC TESTING article. If fuel pressure is OK, go to step  6. If fuel pressure is NOT OK, repair fuel system as necessary. After repairs, erase any stored DTCs.
  6. Check fuel pulsation damper. Connect scan tool to DLC. Test drive vehicle at 1250 RPM on a flat road. Read off short term fuel trim and engine speed (RPM) values. Test value should read about 1.000. If reading is OK, go to step  7. If test value does not vary at approximately 1.000, replace fuel pulsation damper mounted on fuel rail. Go to step  8.
  7. Connect test (breakout) box to ECM and check ground connections. See COMPUTERIZED ENGINE CONTROLS in SYSTEM/COMPONENT TESTS article. Reconnect ECM. Repair as necessary.
  8. Verification. Turn off ignition. Reconnect all connectors and install all components. Connect scan tool to DLC. Test drive car while monitoring long-term fuel trim value until it switches to completed. If DTC is stored, it should have status as intermittent fault.
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