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GH85Carrera GH85Carrera is online now
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Join Date: Nov 2007
Location: Oklahoma
Posts: 85,893
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Quote:
Originally Posted by Jeff Higgins View Post
In my experience across several cars fitted with MFI, the barometric cell has a pretty limited range of compensation. I have yet to see one that can compensate for a 5,300 foot change in elevation. Oh, the car will run across that variation in altitude, but not optimally. It's best to readjust the pump, especially if we have moved from a high altitude home to a sea level home, or vis versa.

We do that by adjusting the main rack, not the idle mix adjustment. I probably wouldn't even bother with the latter, it gets completely overwhelmed by the main rack adjustment.

The main rack adjustment is behind the allen bolt to the lower right of the warm up solenoid. It is best accessed with the speciality tools available for this, the long t-handle allen wrench and the long, very fine tip flat blade screwdriver. Snake them in under the coil, to the left of the fan shroud.

The warmup solenoid is unaffected by changes in altitude. Don't even bother looking at that.
I went to the Boulder, Co area this weekend in my 85 3.2 Carrera. The car ran OK, but it felt like the handbrake was on or I was pulling a trailer. Air pressure up there is much lower. It was nice to get back to my 2,100 Ft. above sea level air pressure.

At sea level, you should notice a real increase in power once things are adjusted right.
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Glen
49 Year member of the Porsche Club of America
1985 911 Carrera; 2017 Macan
1986 El Camino with Fuel Injected 350 Crate Engine
My Motto: I will never be too old to have a happy childhood!
Old 06-24-2025, 02:39 PM
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