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Moderator
Join Date: Dec 2001
Posts: 9,569
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MAP Sensor for MFI
For those of you that are logging MAP with MFI, how did you plumb the vacuum port? I know the 72- throttle bodies have a vacuum takeoff. I have a set of sporto throttle bodies with the ports, but they were plugged at the rebuild. I suppose I could drill a very small hole through the plug and use a barb fittting but would be curious as to what has been proven to work.
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'66 911 #304065 Irischgruen ‘96 993 Carrera 2 Polarsilber '81 R65 Ex-'71 911 PCA C-Stock Club Racer #806 (Sold 5/15/13) Ex-'88 Carrera (Sold 3/29/02) Ex-'91 Carrera 2 Cabriolet (Sold 8/20/04) Ex-'89 944 Turbo S (Sold 8/21/20) |
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05-19-2008, 09:37 AM
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Moderator
Join Date: Dec 2001
Posts: 9,569
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OK, I know nobody NEEDS to log MAP with MFI (unlike EFI). But I have all these extra channels in my data logger. . . need SOMETHING to keep me occupied. . .
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'66 911 #304065 Irischgruen ‘96 993 Carrera 2 Polarsilber '81 R65 Ex-'71 911 PCA C-Stock Club Racer #806 (Sold 5/15/13) Ex-'88 Carrera (Sold 3/29/02) Ex-'91 Carrera 2 Cabriolet (Sold 8/20/04) Ex-'89 944 Turbo S (Sold 8/21/20) |
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05-23-2008, 06:49 PM
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I would rather be driving
Join Date: Apr 2000
Location: Austin, TX
Posts: 9,108
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John, I have not done this exercise with MFI but have done so with EFI. The challenge is getting a clean MAP signal while using ITBs and an aggressive cam. you will need to install a barb on each throat. These will all need to connect together in a ballast tank. I used a section of PVC pipe with end caps as my ballast tank. Back the center with foam to dampen the pulses. Then take a single line off the ballast tank to your MAP sensor for your datalogger.
Without the ballast tank you will get a very choppy signal that will be hard to correlate with throttle openings and such. MAP will change very quickly compared to other parameters.
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Jamie - I can explain it to you. But I can not understand it for you. 71 911T SWT - Sun and Fun Mobile 72 911T project car. "Minne" - A tangy version of tangerine #projectminne classicautowerks.com - EFI conversion parts and suspension setups. IG Classicautowerks |
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05-24-2008, 11:35 AM
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Navin Johnson
Join Date: Mar 2002
Location: Wantagh, NY
Posts: 8,818
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Also you can jamb an old carb jet into the vacuum line to dampen the pulses, that along with the tank will give you a pretty steady vacuum reading.. We usually do something like that on ITB installs.
for the sensor all you need is a basic GM 1 bar MAP sensor. Ill have to check but the signal output is between 0-5 volts and is easily correlated to pressure. You may have to write a function for the logger to interpret the voltage directly to pressure......... easy peasy I have a box full of jets from the good old days 
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Don't feed the trolls. Don't quote the trolls  http://www.southshoreperformanceny.com '69 911 GT-5 '75 914 GT-3 and others |
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05-24-2008, 01:12 PM
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