If the engine is well tuned, good plugs & air filter, starts right up cold and otherwise runs OK then likely everything is as it should be with the fuel system.

There seems to be no definate answer on when to change injectors but they are relatively inexpensive and a potential DIY replacement. They clearly have an important function in the effecient operation of the engine so it is probably not a bad investment. I have not done mine yet though.

I have tried 'injector cleaner' with no noticable benefit. I do however run Premium Unleaded that claims to have higher cleaning properties so this is probably the better investment over the longer term??? Same goes for Mobil 1 that amongst other is promoted to assist with a cleaner (less gunk) engine???

The fact that cracking the throttle slightly 100% solves the warm start & die problem it would seem to be excess fuel in the cylinder related as the additional air is what is required to solve the problem. Perhaps the mechanical nature of the fuel injectors is what makes them prone to a bit of leak-by?

On page 14 of my Owner's Manual it clearly says for a Cold Start "do not depress the accelerator during the starting process". For Engine at Operating Temperature it is a bit more cryptic but ends by saying "at very high coolant temperatures the starting time can be reduced if the accelerator is depressed slowly from the very beginning of the starting process".

Why would they say this for a brand new start of the art car back in 1989. Surely you just need to turn the key????

My understanding of the process is that when an engine is turned off the coolant temperature continues to rise (quite high) without the operation of the cooling circuit and hey-presto you have high coolant temps.

I think this was a politically correct way for the Germans to deal with a known weak point of the M103 engine.

Press the throttle, live with it and save your money for something else.

89 300CE
145k kms