Bmw M21

[djukic]

I need info about M21 engine, specialy about DDE digital diesel electronic.

Recently I have starting problems with my E34 BMW with M21 turbo diesel engine.
Engine cranks OK but it can't start up.

[skr]

welcome, you are like the third m21 to show up round here. try to be more speciffic. what did u check till now? any weird simptoms before this problem started?

[djukic]

Thanks,
Weird symptoms yes, general loss of power, hard starting in the morning, oil consumption...
I had to use glow plugs 5-6 times before starting the engine.
Last year I had problems with throttle pedal. Engine couldn’t rev up above 1300 o/min.
I solved this problem by changing ECU. After that I have loss of power and problems with engine starting.
There is no good source of technical data and diagrams for M21 engine. I bought Haynes but there is no section about diesel BMW engines.

[rob101]

hmmmm
you might want to invest in a compression test. as for the pressure not sure (would be way higher than the gasoline engine as the comp ratio is huge)
where is shogun, i am sure he could point you in the direction of some germans that might be able to help you.
damn i wish they sold the turbo diesel e34s down here :(

[skr]

yeah, compresion test is the way to go. it's cheap and usefull. oil consumption+hard starts in the morning can mean worn rings. compression is around 22:1 if i remember corectly. 19 will do but 16-17 means it ain't gonna start easy or at all in the winter. How much oil consumption? Some is normal, diesels tend to burn more than gasoline. U can loose oil from the turbo being too worn and spitting in the intake, but you whould have lots of black smoke and little power.
Again, some black smoke under full throttle is normal, as the engine doesn't have an AFM (Air Flow Meter), just pre-progamed map.
Now the simple stuff...
-Did you change your filters?
-Do all plugs work? (if they do, after the coil simbol goes out a green circular arrow will light up. it's described as "start readyness"). If it doesn't it means it's time to check plugs. Even 2 not working =>haaaard start.

[djukic]

I inastalled new fuel filter. I will do comression test... What about M21 internet resoruce (data, spec and drawings)?

[djukic]

Problem solved. Fuel solenoid on bosch pump broken. Vhen replaced with new engine starts OK... Thanks...

[Torque]

Glad you tracked down the problem. :)