Sorry for the long thread title.

To summarize from other threads, Dieselkraught awakened the sleeping giant in Ol' Turbo, disabling restrictive '85 specific elements and EGR, and bypassing the overboost protection system. While I was initially comfortable with this setup, some knowledgeable forum members have suggested I reconnect the overboost system in case of a rare catastrophic incident with the turbo.

When I reconnected the system, it immediately went back to the dog it was before. My I-phone has a very accurate dyno application that aided me with these results.

Averaging two runs back and forth on the same terrain I had these results.

With Overboost connected: 23.52 second quarter mile at 60mph...

Obviously a 23 second 0-60 ridiculously slow. We're getting close to 240 territory there.

With Overboost disconnected: 19.55 second quarter mile at 71.4mph.

A 13.75 0-60 time... With a mildly flaring transmission! I estimate another half second would come off with some adjustments to the tranny modulator.

I have results from August, when the car was completely stock: 19.81 second quarter mile at 74.3 mph. 0-60 at 14.13. It was a quick firm shifter at the time.

It seems that something has gone wrong with the overboost system, which was gradual enough for me not to notice. With performance numbers that slow I imagine the car is getting no boost at all. I have read it can be cleaned out, but don't understand how to go about that. I may just replace the entire part and go from there.

Any suggestions? I believe that there is a vacuum leak in the Overboost protection valve itself, because my shifts firm up with the system connected.

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1985 500SL Euro w/ AMG bits 130k
1984 300SD Turbodiesel 192k
1980 240D Stick China 188k
2001 CLK55 AMG 101k
2007 S600 Biturbo 149k Overheated Project, IT'S ALIVE!!!