How is this done? I heard that doing this results in alightly increased performance.

I did it on my '85 300D
 

Removed the solenoid valve mounted on the firewall adjacent to the fuse box. I ran the "tubing" straight from the banjo fitting to the android valve connection.
Jim

[Edited by engatwork on 05-19-2001 at 10:21 AM]

Jim,

The EPA Gustapo will be knocking on your door tomorrow.
I would never publish this information.

P E H

The valve does nothing unless you have a overboost condition. It then reduces boost. You could fry your engine if you disconnect. I tried it on mine and could tell no difference so I hooked it back up. At the time I was trying to disconnect the EGR. The EGR is what you should disconnect, if possible, not the overboost protection circuit!

1995 S-350
141,000 miles

After removal I put
 

a test gauge on the line from the banjo fitting and observed the pressure. Ran it up to between 9 and 9.5 psi at, if my memory serves me correctly, around 4k rpm. I can live with this much boost.
Jim
'85 300D
'95 E320
'97 CRV

How much boost did you have before doing the disconnect? If I am remembering correctly my 350 runs about 14psi boost.

FYI: I measured 12-13 lbs of boost on my 87 300SDL a week ago. I imagine that this is about what most of the mid to late 80's engines should be running for boost at WOT. The EGR should be closed down at WOT and should not make any difference in boost pressure at that speed if it is disconnected, or not..

vhunter
 

That is correct, but running not under full throttle the EGR makes a lot of difference on performance and fuel milage. Plus it clogs up the intake system.

The over boost protection solenoid performs two valuable functions. It vents excess boost (over 14 to 15 psi) in the event of waste gate malfunction, and it vents unneeded boost during deceleration. This latter function allows the ALDA to cut back on fuel enrichment during off throttle operation resulting in better fuel economy and lower emissions. I posted this like with another thread but it serves well here too.

http://hsb.baylor.edu/html/easley/autofaqs/boostchk.htm

Bob D.