W202 2.5 Diesel suddenly loosing Power

[chalp]

Hi
I have a mysterious problem with my 1999 W202 2.5 diesel estate. After about half hour of driving, if I put my foot down it seems to have about half power. It will change down the gearbox, but struggle to accelerate. If I stop the engine and immediately restart, that's it OK again.
It did this every day for 2 weeks, stopped doing it for a month, now started it again last week.
I got a MB dealership to look at it, they could not find anything wrong, but thought it may be the turbo, (turbo boost pressures were OK). If I take it back, they are going to fit a new turbo and charge me a fortune.
Probably not connected? but whenever I accelerate hard, the AC stops working and I get full hot air blowing into the cabin.
Can anybody help? Anybody seen this before?
regards
Paul

 

[television]

I know that we say that its often the MAF as these do not always show up on the test set.

You could try running it with the MAF unplugged if it is OK you have the answer and cost nothing to check

 

[chalp]

Thanks Malcolm. Excuse my ignorance, but how can I find the MAF to unplug it? I am not sure what it looks like.
Paul

 

[Dieselman]

No MAF on a 250 turbo.

It can't be the turbo if it's blowing full boost and these are simple turbos with wastegate, not a vane ring.

My guess says either EGR valve not working or boost actuator module split so leaking vacuum.
Next guess is the MAP sensor on the inner wing.

Switching off the aircon for full power is normal, it's to ensure maximum power to the wheels.

 

[chalp]

Thanks Dieselman. It was a split pipe. How could a MB dealership miss that and tell me they couldn't find anything wrong? Anyway, nice to have my turbo back again!
best regards
Paul

 

[KillerHERTZ]

Diesel's dont have MAFs do they?

 

[GazCaff]

Diesel's dont have MAFs do they?

The more up to date ones do.