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Home >> Audi >> 1990 >> 200 Base, Automatic >> Repair and Diagnosis >> Engine Performance >> Engine Controls - Adjustments >> Idle Speed & Mixture >> 4-Cylinder >> 2.0L Engine

2.0L Engine

  1. Ensure engine is at normal operating temperature. Ensure all electrical accessories and cooling fan are off. Increase engine speed to 3000 RPM then allow to idle for at least 2 minutes. Turn ignition off.
  2. Using Test Adapter (VW 1363/3), connect CO tester to measuring tube. Connect Multimeter (US 1119) with Test Adapter (VW 1315A/1) to differential pressure regulator. See Fig 1 .
  3. Turn ignition on. Control current must be positive. If not, reverse test probes. Remove crankcase housing breather hose and vent to atmosphere. Remove sealing cap from top of charcoal canister.
  4. Connect timing light and check ignition timing. Refer to the 4-CYLINDER IGNITION TIMING  table for ignition timing specifications. If necessary, remove tamper proof seal covering distributor clamp bolt and adjust ignition timing. After adjusting ignition timing, tighten bolt and install a new tamper proof seal.
    Fig 1: Checking Engine Settings
    G93045Courtesy of AUDI OF AMERICA, INC.
  5. Check idle speed. Refer to the 4-CYLINDER IDLE SPEED & CO LEVEL SPECIFICATIONS  table. If idle speed is incorrect, check air intake system for leaks. If necessary, check/adjust airflow sensor potentiometer. If idle speed is correct, turn A/C system on (if equipped). Idle speed must increase by 70 RPM. If not, check CIS-Motronic computerized engine control system.
  6. Check CO content by reading milliamp (mA) output on multimeter. Reading must fluctuate between zero and 5 milliamps. If reading is incorrect or it does not fluctuate, check oxygen sensor control system.
  7. Read CO value on CO tester. Reading must be .2-1.2 percent by volume. If CO content is outside range, adjust idle mixture. Turn ignition off and remove rubber boot from mixture control unit.
  8. Punch hole in center of CO adjusting screw plug and drill a 3/32" hole to a depth of 5/32". DO NOT  drill completely through, as adjustment screw will be damaged. Install a 1/8" sheet metal screw and remove plug using pliers.
    NOTE: DO NOT  push down on adjustment screw and DO NOT  accelerate engine with adjustment wrench in place. Remove wrench after each adjustment and accelerate engine briefly before measuring CO level.
  9. Install rubber boot on mixture control unit. Start and run engine at idle. Using Adjustment Wrench (P 377), turn adjustment screw clockwise or counterclockwise to adjust CO level. See Fig 2 . Install new plug in mixture control unit.
Fig 2: Adjusting Idle Mixture & CO Level
G93046Courtesy of AUDI OF AMERICA, INC.
4-CYLINDER IDLE SPEED & CO LEVEL SPECIFICATIONS

Application Idle RPM CO Level %
All Models 780-900 .2-1.2
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