A defective auxiliary choke may cause the engine to stall or run rough during the warm-up phase or have an irregular idle.
Examination
Caution: The engine must be cold when checking.
Disconnect the auxiliary air damper connector, (right bottom arrow).
Connect a voltmeter to both pins of the connector.
Start the engine. The voltmeter should show the voltage of the battery, otherwise find and repair a broken wire.
Reconnect the connector.
Start the engine and let it run at idle speed.
Disconnect the hose from the auxiliary choke, after which the engine idle speed should drop.
Warm up the engine and disconnect the hose again. In this case, the engine speed should not change. Otherwise, replace the additional air damper.
Replacement
Disconnect connector.
Loosen the clamps and disconnect the hoses.
Unscrew the 2 mounting bolts and remove the additional air damper.
The flap is visible through the cover. When hot, the damper must be fully closed. When cold, there should be a gap. When heating the additional air damper, apply battery voltage to the connector contacts with auxiliary wires.
Insert and screw on the additional air damper.
Connect hoses and secure with clamps.
Attention: Make sure that the hoses are securely installed.
Connect connector.