Originally Posted by engatwork

I have seen plugged cats on a 98 E300 that was driven for a long time exactly as described above on 100% biod. Don't remember exact code.

Are you able to watch the boost pressure when turbo spools up? What is it coming up to?

Originally Posted by E300D

We did replace a whole bunch of parts after a full diagnostics of the CDI

We had fuel pressure issues that threw the car into limp mode as well as noise LP pump.

What I also need to mention is that the P.O run the car for approx 50K miles on Biodiesel...

So what happened was that he got the limp mode and dealer assumed the whole car fuel system is dirty and needs to be replaced. I took a chance on the car and bought it.

The fuel pressure problem went away after we swapped out the fuel pressure sensor at back of the fuel rail.

The noise fuel pump aka lift pump aka low pressure pump was replaced with a new one along with a fuel sender unit.

Additionally the HP pump was replaced due to a stuck internal fuel return valve.

MAF was also replaced since we did not get any readings from it.

So right now the car runs good. No codes and and engine runs smooth. However the issue of low power remains.

Why I think I should revising the CAT is because we disconnected at the turbo but did not really drive the car at a good speed to notice a difference. Sure the turbo was spooling up louder and I did notice the electronic VNT actuator move as it should.

So I think I shall go back, unplug the CAT and go for a boot in the car.

Another suspect I have is a blocked intake manifold. However when I pulled out EGR valve it was clean as a whistle.

Now back to the point where PO used Biodiesel in the car: The car had already approx 30-40K miles when he started using biodiesel.

I do not have sufficient knowledge of biodiesel but I know MB allows only something like a 20% blend with petrol diesel. Well from what I gathered the PO run B100 or 100% biodiesel.

From what I understand biodiesel burns clean and acts as a detergent, cleaning out crap and such from the engine. In theory, is there a possibility where a whole bunch of gunk and crap from the combustion process clogged up one of the cats over the last 60K miles?

I have not done any 0 to 60 times. The car seems fine but lacks that responsiveness.

I have switched bet Winter and Summer mode but not big difference in response.

If I hold the car against brakes and let turbo spool up it takes off, but I am unable to activate traction control. Also there is very little black some if any when I floor it.

Thanks guys,