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Registered
Join Date: Jul 2011
Location: Michigan
Posts: 257
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Altitude Control Unit
Does anyone know what this unit does. I pulled my drivers seat today and noticed this unit underneath. I don't believe it was connected but I am not completely sure whether it was or not. Lets just say when I went to remove the wire connection it either was not connected or the connector was not tight. I believe it should be left disconnected but I am not sure.
Part number is 944 606 151 00 picture attached. 
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Tom 1987 911 Targa 1987 944 Turbo 1976 911S 1973 Mustang Mach 1 351C |
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02-14-2015, 05:44 PM
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Member 911 Anonymous
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It adjust mixture on extreme altitude change. If you are not in a mountainous area then I guess you can leave it unplugged???
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'85 Carrera Targa Factory Marble Grey/Black * Turbo Tail * 930 Steering Wheel* Sport Seats * 17" Fuchs (r) * 3.4 * 964 Cams * 915 * LSD * Factory SS * Turbo Tie Rods * Bilsteins * Euro Pre-Muff * SW Chip on 4K DME * NGK * Sienes GSK * Targa Body Brace PCA/POC |
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02-14-2015, 05:59 PM
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Registered
Join Date: Jul 2011
Location: Michigan
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Ok but sounds like plugged or unplugged it should not matter. I do have a different chip than stock in this car would that change anything?
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Tom 1987 911 Targa 1987 944 Turbo 1976 911S 1973 Mustang Mach 1 351C |
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02-14-2015, 06:12 PM
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Posts: 1,230
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Plug it back in. It is part of the computers input, no downside if plugged in.
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02-14-2015, 06:52 PM
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Diss Member
Join Date: Jul 2002
Location: SC - (Aiken in the 'other' SC)
Posts: 5,020
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It is a simple on off switch that flips at 3500 feet (or somewhere else in the 3K range...).
No reason to disconnect it simply because you aren't apt to remember when you go on that one drive through the mountains.
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- "Speed kills! How fast do you want to go?" - anon. - "If More is better then Too Much is just right!!!" - Mad Mac Durgeloh -- Wayne - 87 Carrera coupe -> The pooch. |
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02-15-2015, 06:56 AM
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As Wayne said it's a simple switch that closes above a certain altitude to compensate for the lower air density up there.
The DME will lean out the mixture when this switch is closed. However, this is done through software and the switch is read through one of the A/D converter channels. So if the chip maker has enough skills this could have been be disabled with an aftermarket chip. Not that there is a reason for it. Only way to test would be to simulate the switch closed and check that fuel signal changes slightly. So I'd connect it back after verifying the switch is open while you are close to see level. Ingo
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1974 Targa 3.6, 2001 C4 (sold), 2019 GT3RS, 2000 ML430 I repair/rebuild Bosch CDI Boxes and Porsche Motronic DMEs Porsche "Hammer" or Porsche PST2, PIWIS III - I can help!! How about a NoBadDays DualChip for 964 or '95 993 |
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02-16-2015, 01:16 AM
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I had a thought once that maybe this switch could be tested by putting it in a vacuum bag and pulling a slight vacuum? Has anybody tried this, or want to (easily) defeat my atmospheric knowledge?
Chuck.H '89 TurboLookTarga, 391k miles |
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02-17-2015, 05:21 AM
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Marble Grey
1974 Porsche 911 Targa 3.6
2014 
