99 Mercedes 300Td Poor Run/ Misfire

Greg Owner Washington Posted   Latest   Edited  
1999 Mercedes-Benz E300 3.0L (606.962) 5-spd (722.6) — WDBJF25H6XA921963
White Smoke/ Misfire

Please help MB Techs!!! We have exhausted our resources. We are desperate to help this guy. 

This 300 td starts perfectly cold and idles like brand new but as it warms up it gets rough, starts blowing white smoke when trying to accelerate and misfires. Will barely rev up from idle. Hot - idles normally most of the time but intermittently "pops" through the intake and misfires. Even when idling cold it emits some white smoke. Engine is sound mechanically and only has 63k on the odometer. Smooths out at 3000 rpm like someone flips a switch. 

This is the Bosch electronic pump - a two year only run I have heard. We have done everything we can think of:

Cleaned fuel tank and screen of algae, added cleaner to tank (algicide). Cleaned out fuel line. Replaced all clear lines, main and pre filters, (sucking air). All injectors. Ordered and installed a used pump out of desperation - no change at all. We have disassembled ecu - inspected for solder joint issues - nothing. EGR has been tested and functions properly. New glow plugs (THREE WERE DEAD), replaced leaking warm up component that the fuel flows through (sorry about the non tech verbiage there), verified proper turbo boost/ function, probably things I have forgotten. 

What amazes me is that the car runs just the same with both pumps and a diesel is diesel- just the fuel injected at the proper time creates combustion ( of course)- that's why we cant get past both pumps making the car rune exactly the same. If I had to guess, it seems like it is over fueling big time but how and why? Does anyone know of a place that can test the ECU for this type of issue? What would cause it to run exactly the same with both pumps? I feel we are missing something - maybe ECU? Could we have a temp sensor or something like that not showing bad when tests? is it possible two pumps would be identically faulty?

Thanks to all for the help - fight the good fight!!

James Owner/Technician

Is this vehicle setting any codes? Does it act different with the Air Mass disconnected?

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James Owner
United Kingdom

Have you checked the profile of the cranks sensor signal? A bad signal will cause all sorts of trouble.

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