Got a call from my buyer today, the car is STILL at Mercedes and the tech (Eric) is still stumped.
Here's where it gets
weird -- they pulled plugs, and he said they were completely fouled. Like,
black.
Now, remember that I'm running a stock fuel injector setup -- it doesn't get more conservative. Furthermore, I'm running the smallest pulley available for the supercharger, so in all actuality the car should be too LEAN, not too rich.
The Mercedes tech basically told my buyer that the car was "heavily modded" and would take thousands to fix.
I told my buyer that, once again, Mercedes revealed their ignorance because the car literally has three engine mods:
Aside from that, there's only the Walbro 255 fuel pump which was put in place when the previous OEM fuel pump developed a leak at 40,000 miles (per the previous owner).
And that's it.
Hardly a "lost cause" as Mercedes told him. As Steve said, if they can't read a code, they're lost. And this is why we've never gone to them.
Once again, I've directed my buyer to this forum; hoping he comes on so he can learn that the car truly isn't a lost cause, it just has a head-cold.