The injector pump timing factor you are speaking of compensates for camshaft chain stretch. 11* degrees is about maximum stretch on the chain. There is no ignition system you understand.

But if the car has been dealership maintained, this should already be set correctly. It's the kinda thing you do about every 100k miles or 3-4* degrees of chain stretch.

But whether or not altitude is factor for injector pump timing is an interesting idea!! Nevertheless you are using gasoline logic if you think 'ignition timing' is the answer.

Major factor is that low-land old lady cars are often the most sluggish diesels of all with carbon fouled piston crowns and valve seats from constantly being driven at low rpm's and never being correctly warmed up. Diesels need clean piston crowns to concentrate heat which ignites the engine on its own accord. The only remedy is high rpm running for extended periods of time to burn the combustion chambers clean.

And Larry aint jokin when he talks about carrying an extra fan belt. ONE belt operates the alternator and water pump too. Selectively search Larry's posts and you will get some darned good advice.

Of course the alternator bracket is the biggest joke on the 240D.... you will see, the ridiculous alt bracket is more complicated and has more weaknesses than the entire car.