Ausmbtech

Just hoping that anyone here with a C250TD and a boost gauge could do a test for me.

I have a problem with a C250TD which boosts to approx 15psi, dropping to about 13 psi around 4000rpm under full load. Normal. But during the full load gear change the boost pressure drops to about 2-3psi and then the turbo needs to spool up again like i've only just given full throttle.

Basicly it's like the turbo is "stalling". I believe it may have a partially blocked exhaust but there is power when the boost is up, it just drops of very easily so I'm a bit suspicious of the turbo itself.

Anyone who can either test with a boost gauge or let me know how their vehilce feels at full load gear change would be much appriciated. Unfortunately there aren't many C250td in Australia so I can't compare with one myself.

Untertürkheim

I do not own a car with a OM605A engine, but the symptoms would lead me to think it may be a vaccuum related issue where the variation in vacuum at the point of shifting (perhaps from the modulator) causes the wastegate to open (which I believe is also vacuum controlled).

Have you tried measuring the vacuum at the wastegate and transmission modulator to see if there is a correlation with boost?

Ausmbtech

Rechecked the vac to the modulator, it has a consistant supply.

I found a few vids on youtube of C250td's and E250td's, there is definately a problem, this engine doesn't respond so fast after a gear change.

Looks like I'll have to get a exhaust backpressure tester fitted somehow.