Idle speed and CO content — check (Audi 80 B4)

AUDI 80 cars with a five-cylinder engine have automatic idle speed control. It is not possible to adjust the idle speed. It can only be checked. If the test conditions are met, the system should automatically adjust to the nominal idle speed of 720-860 rpm. If this does not happen, then the following must be done:

1. Check the condition and tightness of all air intake parts (hoses, gaskets). Due to air leakage, the change in engine idle speed may be so significant that the stabilization valve will not be able to bring it back to normal.

2. Interrogate the self-diagnostic system data storage device. The system may have another defect. The conditions for performing the idle speed test are correctly adjusted ignition, warmed-up engine, and normally functioning fuel injection and ignition systems. During the test, all on-board network consumers must be disconnected. The radiator fan must not operate.

3. Remove the crankcase ventilation hose from the distributor and plug it with a plug.

4. Remove the engine oil level indicator rod and cover the dipstick hole with a rag.

5. Clamp the hose from the throttle body to the EVAP valve, which runs above the air intake hose.

For a car owner, independent CO testing is hardly justified, considering that it is mandatory to perform during a technical inspection, and in addition, the car owner is unlikely to have a gas analyzer at his disposal.

6. Install the gas analyzer into the CO measuring tube located in the front of the engine compartment. Make sure that the gas analyzer has a tight fit on the tube.



7. Disconnect the lambda probe plug.

8. Start the engine and let it idle. The gas analyzer should show 0.1-1.1%. If necessary, make adjustments using the CO adjustment screw. To do this, remove the plug from the CO adjustment screw.

9. Drill a 2.5mm diameter hole in the cork and screw a 3mm diameter screw into this hole.

10. Remove the plug using pliers.

11. Press the accelerator pedal after the adjusting screw has been turned, and then check the reading on the gas analyzer.

Attention! The accelerator pedal may be pressed only after the key used to adjust the CO has been removed from the adjusting screw.

Note: Self-checking of CO is usually not so important for a car owner, considering that it is mandatory to be performed by a workshop. In addition, a car owner usually does not have a device for measuring CO.