Idle Speed & Mixture: 2.3L
NOTE:
Idle speed on vehicles with 2.3L engine is electronically controlled and CANNOT be adjusted.
- Ensure engine is at normal operating temperature. Turn ignition off. Ensure all electrical accessories and cooling fan are off. Remove cap from exhaust probe receptacle and connect CO meter. Ensure fit is snug to prevent exhaust leaks.
- On 100 and 200 models, remove vent hose from elbow at intake air boot. Leave elbow unplugged to draw fresh air through opening. Remove crankcase breather hose and plug cylinder head openings. See Figure . Crankcase vapors must vent to atmosphere.
- On 80 and 90 models, remove sealing cap from top of charcoal canister. See Figure . Remove crankcase housing breather hose and vent to atmosphere. Crankcase vapors must vent to atmosphere.
- On all models, connect Multimeter (US 1119) with Test Adapter (VW 1315A/1) to differential pressure regulator. See Fig 1
. Set scale to 200 milliamps (mA) DC. Start and warm engine to normal operating temperature.NOTE: If injection lines were disconnected or replaced, increase engine speed to 3000 RPM several times then allow to idle for at least 2 minutes to bleed injectors and lines.
- Insert fuse in fuel pump relay. Malfunction indicator light must come on to indicate that ignition is stabilized for testing. Connect timing light and check ignition timing. See IGNITION TIMING table for timing specifications.
- If timing is incorrect, loosen distributor clamp bolt and turn distributor. Remove fuse from fuel pump relay. Increase engine speed above 2500 RPM then allow it to return to idle. Ensure Ignition timing fluctuates between 7-20 degrees. Tighten distributor clamp bolt.
- Check idle speed. Idle RPM must be within specification. See IDLE SPEED & CO LEVEL SPECIFICATIONS (2.3L)
table. If idle speed is not within specification, check air intake system for leaks. Idle speed is electronically controlled and is NOT adjustable.IDLE SPEED & CO LEVEL SPECIFICATIONS (2.3L)
Application Idle RPM % CO Level Checking Value 720-860 .3-3.0 Adjusting Value 720-860 .6-1.0 - If necessary, check differential pressure regulator current with oxygen sensor connected. Reading must fluctuate between 4 mA and 6 mA, and CO level must be 0.3-1.2 percent.NOTE: On 80 and 90 models, turn A/C system on. If idle speed drops severely, check idle stabilization system.
- Disconnect oxygen sensor harness and check CO content. Reading must be 0.3-3.0 percent by volume. If CO content is outside range, adjust idle mixture. Turn ignition off. Remove rubber boot from mixture control unit.
- 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 accelerate engine with adjusting wrench in place. Remove wrench after each adjustment and accelerate engine briefly before measuring CO.
- Install rubber boot on mixture control unit. Start and run engine at idle. Using Adjustment Wrench (P 377), turn adjustment screw clockwise to reduce or counterclockwise to increase CO reading. See Fig 2 . Install new plug in mixture control unit.