Air/Fuel Mixture: Adjustments

1. Initial setup
a. Engine at normal operating temperature, 80°C (176°F).
b. All electrical consumers (including A/C) switched OFF
c. Oxygen sensor connected.
d. Connect an exhaust analyzer to the exhaust manifold sampling tube.
e. If any fuel lines in the injection system have been opened prior to testing, accelerate the engine to about 3000 rpm several times, and let it idle for at least 2 minutes before testing.
2. Connect test harness VW 1315 A/1 between the differential pressure regulator and the harness connector.
3. Connect a multi-meter to the test harness.
4. With the engine idling, differential pressure regulator current should be 0mA - 5mA, and fluctuating slightly, and CO% should be 0.2% - 1.2%.
5. If The current does not fluctuate, check the oxygen sensor wiring. If the wiring is OK, replace the oxygen sensor.
6. If the current and the CO are not within specification, adjust as follows:
a. Drill a 2.5 mm (3/32 in) hole in the concealment plug (located in the air flow sensor housing between the air boot and the fuel distributor), and use a sheet metal screw to extract it.
b. Disconnect the oxygen sensor.
c. Use a long 3 mm allen wrench (tool P377 or equivalent) to adjust the CO to 0.2 - 1.2%.
7. After adjustment, install a new concealment plug.


**EMI