Remove the distributor cap and pull out the spark plug tip.
As a rule, the ignition timing is not adjustable. A stroboscope is required for checking.
Warm up the engine to operating temperature: the coolant temperature should be about 70°.
Connect the strobe light according to the instructions.
Caution: The vacuum supply on the engine distributor vacuum pipe remains connected or must be removed.
The air conditioning system must be switched off.
Start the engine and let it idle.
Caution: Do not pull the tip by the wire.
Check the resistance between the individual contact on the distributor cap and the corresponding contact on the spark plug tip. Reference value 1 kOhm.
[Article was obtained from the portal: MERCEDESMAN]
If this value is not reached, unscrew the tip from the wire. The tip resistance should be 1 kOhm. If not, replace the tip, otherwise replace the wire or the distributor cap.
If the resistance is higher, strip the ends of the wire and repeat the test or replace the wire.
Check the distributor rotor.
Connect the ground wire to the battery.