Engine With Two Knock Sensors

Requirements:
Engine at normal operating temperature, 80°C (176°F).
All electrical consumers (A/C, rear window defroster, etc.).
Radiator fan must not be running while checking or adjusting.
No fuel preassure gauges connected to the fuel system.
Throttle valve in the proper idle position.
Throttle valve switch must be adjusted properly and working.
Exhaust system must be tight and free from leaks.
Oxygen sensor system in good working order.
NOTE; If the injection lines were loosened or replaced, run the engine up to at least 3000 RPM several times to clear the system of trapped air before making adjustments.

1. Initial setup
a. Disconnect the harness connectors from both charcoal canister solenoid valves.
b. Remove the cap from the elbow on top of the intake air boot. (The elbow contains a calibrated orifice and must remain in the intake air boot.
c. Remove the crankcase breather between the intake air boot and the valve cover.
d. Plug the hose.
e. Connect a test harness (VW 1315 A/2 or equivalent) between the idle control valve and the harness plug.
f. Connect a multi-meter to the test harness, and set it to the 2 amp range.
g. Connect an exhaust analyzer to the exhaust sampling port.

2. Check idle speed
a. Start the engine and let it idle.
Idle control current should be 430 mA
b. If the current reading is not within specification, adjust the idle by turning the screw in the throttle housing.
c. After adjustment, idle speed should be 720 +/- 50 RPM.