I had seen an add for a manual boost control for turbo engines. My question is will such a thing work on a 1995 S-350 or will the computer sense it and send a fault.

Or another question - will the boost pressure or alda get out of adjustment over time and need timkering with?

1995 S350
143,000 miles



[Edited by oldsouth on 06-20-2001 at 10:31 PM]

Manual boost controllers will work on basically any turbocharged car. As for your second question, the boost pressure gets "out of adjustment" as the wastegate spring gets old and loses tension. I would imagine that the same thing goes for the ALDA. Your car is new enough that neither should be of concern at the moment.

What I had in mind was to install a manual boost pressure control where I could make sure the boost was at 14 psi then disconnect the EGR valve. When I disconnect the EGR the computer cuts boost pressure. I would be bypassing the computer and controlling boost manually. I think on this car that the ALDA works off of boost pressure only and has no wires going to it. Therefore the computer could do nothing to cut any power. I have tried every way I know how to disconnect the EGR and have been unsucessful, but I think this might work. Any ideas anyone.

Old South,

Was doing a search for ALDA information and came upon your statement re: disconnecting the EGR on your 603 engine ... I think your engine is much the same as the one in my 91 350 SDL, right?

Well, it seems like my performance is down ... so, I was cleaning vacuum lines, etc ... I had previously removed intake and cleaned out 10 years of crud associated (I think) with the confluence of EGR heat into the intake where the valve cover recirc entered ... looked like the EGR had been cooking off the oil fumes ... figured this may have been related to the momentary hesitation and puff of brown smoke on occasion, during extended highway driving.

Can you give me more info re: the EGR disconnect? I plugged mine, so ... if this causes sensing to occur that reduces the boost output, it would seem logical this is my problem.

Thanks!

__________________
George Stephenson
1991 350 SDL (200K and she ain't bent, yet)
former 2002 E320 4Matic Wagon - good car
former 1985 300 CD - great car
former 1981 300 TD - good car
former 1972 280 SEL - not so good car
a couple of those diesel Rabbits ...40-45 mpg

You say: "When I disconnect the EGR the computer cuts boost pressure" How are you disconnecting the EGR? Simply unplugging it? How does your engine "know" the EGR is functioning? How about simply putting a block-off plate made out of 1/16" aluminium behind the EGR and leave it installed? Maybe this would trick the system into thinking the EGR was functional as the valve would open and close but no gas would flow? Just a thought. RT

__________________
When all else fails, vote from the rooftops!
84' Mercedes Benz 300D Anthracite/black, 171K
03' Volkswagen Jetta TDI blue/black, 93K
93' Chevrolet C2500HD ExCab 6.5TD, Two-tone blue, 252K

Thanks, RWT,

I don't know how the engine "knows," but was following up on a comment made by OldSouth in this thread.

Idea on plating off the EGR is a great one ... would allow the valve to continue to work and would not "show" any modifications while still keeping the heat out of the intake, thereby preventing coking of the oil fumes.

__________________
George Stephenson
1991 350 SDL (200K and she ain't bent, yet)
former 2002 E320 4Matic Wagon - good car
former 1985 300 CD - great car
former 1981 300 TD - good car
former 1972 280 SEL - not so good car
a couple of those diesel Rabbits ...40-45 mpg

I could be wrong but I don't think the engine has sensors that "read" exhaust or intake gases to meter the EGR so likely a block-off plate would work. Try it and see it would be very easy to remove if it doesn't... I also would like to know how the computer controls the boost. Never heard of an electronic wastegate per se but have seen them controlled by vacuum. The system may use vacuum to hold the wastegate shut and then vent to release boost. Or it may be a springloaded standard wastegate with a vacuum assist to dump boost if commanded by the computer. Disabling should be fairly simple and easily returned to stock if it doesn't work out. Sounds like fun. RT

__________________
When all else fails, vote from the rooftops!
84' Mercedes Benz 300D Anthracite/black, 171K
03' Volkswagen Jetta TDI blue/black, 93K
93' Chevrolet C2500HD ExCab 6.5TD, Two-tone blue, 252K