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Home >> Audi >> 1984 >> 5000 4D Sedan, 2.2 C >> Repair and Diagnosis >> Engine Performance >> System >> Fuel Injection System - BOSCH Cis-E (Turbo) >> Testing >> Electrical Component Test >> Idle Speed Stabilization

Idle Speed Stabilization

  1. Engine must be at normal operating temperature, ignition timing must be correctly set and A/C switched off. Connect Tester (VW1367) using cable Adapter (US 1112).
  2. With O2 sensor connected, duty cycle should be 26-30%. If duty cycle is not correct, readjust. See appropriate article in the TUNE-UP section.
  3. If duty cycle can not be adjusted, and reading is 33% or 40%, check that A/C is switched off. If A/C is off, check idle switch or open circuit between idle switch and control unit connector.
  4. If duty cycle fluctuates between 20-25%, check for open RPM signal circuit from electronic ignition control unit. If duty cycle is 25% and idle speed is incorrect, check for leaks at throttle body seals and gaskets.
  5. If there are no leaks at throttle body, check for open circuit at between idle stabilizer and control valve. If circuit is okay, replace control valve.
  6. To check A/C switching signal, switch A/C on with engine running. RPM should increase about 100. If no RPM increase, check for open circuit between dash switch and control unit connector terminals 6 and 16.
  7. To check A/C compressor signal, start engine. Switch A/C on. When the compressor has cycled off, the RPM increase should be about 100. If idle increases over 1000 RPM with A/C compressor off, check that voltage signal wire from compressor to control unit connector terminal 19 is not interchanged with terminal 16.
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