Idle RPM and CO emission

[Ronnie Karlsson]

My car is a  280 SL 1971, one of the very last made with transitorized ignition module and emission relays.
My mechanic has a problem with the CO emission after adjusting the idle rpm.
CO emission value changes after it has been adjusted. Idle is adjusted to a CO value of 1%. Restarting the Engine later and the CO value has changed randomly to a value between 0% to 8 %.
All other things that has to be checked and controled before adjusting idle has been done, i.e. points, linkage etc.
Now he suspect that the FIP is not working ok.
Anyone that has an idea or proposal are welcomed.

Regards
Ronnie

[MikeSimon]

Ronnie:

Different subject. Could you check the ID and casting-no on your cylinder head, on the left side where the fuel injection pump sits?
Much obliged!

mike

[Ronnie Karlsson]

I don't have accsess to the car right now. My mechanic lives 200 km away from me. I do know however that the Engine don't have a Engine number stamped as it is one of the last 280 SL. It only have 280-SE/A on the engine block.

The fuel consumption when driving is also very high, 16 liters per 100 km.

Ronnie

[ja17]

Any kind of random ignition mis-fire will change the CO readings.  Double check the spark plugs and wires. If the plugs are getting gummed-up from rich running, the CO will change as mis-fires occure.