What size Allen Wrench ?
 

What is the size of the Allen Wrench used to adjust the screw which is accessed through the hole in the Air Cleaner ? This is for CIS injection systems as in my 84 380SE.

I was having a starting problem where the morning start was great (because Cold Start Valve providing extra fuel). Thereafter, trying to start even after 5 hrs, it used to take 30 turns of the engine to start it. I noticed that the throttle plate was not lifting. I want to try to tweak the CO adjustment screw and see if that makes a difference. Is this the right approach ?


Thanks,

Amit

Be careful of confusion due to labelling. The throttle plate is likely not visible. It is hidden well below the airflow meter plate. The throttle plate is connected to the throttle linkage, and can be expected to open when the accelerator is pressed. It is bypassed by the idle control valve, whose opening is controlled by the engine management computer.

The airflow meter plate is not operated by any linkage or computer. It is designed to open as a function of airflow demand - as airflow increased, it is pulled open by the differential air pressure only. It is linked to the fuel distributor, and determines mechanically the fuel mixture.

Now reanalyse what is happening.

Steve

Check the condition of the idle control valve hoses before twiddling with the mixture. They are probably rock hard by now, and leaking. This will result in no fuel hot (no cold start valve), and hard starts.

The idle control valve is under the air filter housing, about half the size of a coke can. One electrical connection, two 1/2" or so ID rubber hoses.

Peter

3MM

I apologize. I was refering to the Airflow meter plate. That is not lifting when I am trying to start after say 5 hrs.

As for the idle control valve hoses, if I depress the accelerator while starting, would it not make the malfunctioning idle hoses a moot point ? The car is difficult to start even when I depress the pedal.

Finally, after 5 hrs of sitting there, the engine is not really "hot ".

Thanks,
Amit