Table of contents: Test location 1000 m below sea level ↓ Test location 1000 m above sea level ↓
Caution: Idle speed, CO content and ignition timing must be checked and set together. Idle speed cannot be adjusted. The idle speed adjusting screw must be fully tightened. The screw is varnished and must not turn. The speed is adjusted solely by stabilizing the idle speed. From 3.88 the screw is not provided.
Remove the crankcase ventilation hose. Plug the air bleed tube with the CO measuring pipe plug.
Connect the ammeter to the electrohydraulic regulator.
Start the engine and let it idle.
Check the operation of the booster valve switch and the idle contacts of the throttle position sensor. To do this, briefly increase the speed to 4000 rpm and close the throttle valve by hand (release the pedal). In this case, the measuring device should show minus 50-60 mA for a short time. If a positive value is indicated, swap the measuring device cables. If there is no current, check the idle contacts.
Test location 1000 m below sea level
Check the current readings: it should be 0±3 mA, the CO content should be 0.3-1.2%.
Otherwise, remove the plug of the CO adjusting screw and adjust the control current 0±1 mA. Adjustment is the same as for a 90 hp engine.
Test location 1000 m above sea level
Disconnect the lambda probe plug connection (green wire).
Let the engine idle. Measure and record the control current on the electrohydraulic regulator in mA. Its value is the correction value of the height sensor.
Connect the lambda probe plug and measure the control current again. If the new value differs from the previously recorded value by more than ±3 mA, the CO content must be adjusted by changing the control current.