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Chain fence eating turbo
Join Date: Dec 2008
Location: Austin, TX
Posts: 9,138
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Carrera Airflow Meter test question
Using the 9-volt battery test, in the first 5-10 degrees of travel, the voltage would not increase at all. Then, after I get past that point, the voltage would jump about 0.3 to 0.4 volts higher.
Is this normal or not?
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Cory - turbo'd '87 C3.2 Guards/Blk, 3.4, 7.5:1 CR, 993SS cams, Borg-Warner S366 turbo @ 1.2-1.5 bar, Treadstone full bay IC, 70mm TB, TiAL F46 WG, HKS 1 1/2" BOV, twin 044 pumps, MicroSquirt AMP'd w/GM smart coilpack, Bilstein coilovers, Tramont replica Speedlines (285's rr, 225's frt), Big Reds frt, 993 rr., tower brace, MOMO wheel Last edited by Tippy; 08-11-2011 at 06:54 AM.. |
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08-11-2011, 06:34 AM
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porsher
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no, no jumps in voltage
a smooth and steady increase as the flap is opened. Air Flow Meter (AFM) - from "The 944 Motronic DME" by FR Wilk* ©2001 www.the944.com
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86 911 Race Car, with a few 993 bits in the boiler room 79 928 Race Car 88 928 Becoming a Race Car |
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08-11-2011, 09:45 AM
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Chain fence eating turbo
Join Date: Dec 2008
Location: Austin, TX
Posts: 9,138
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Quote:
__________________
Cory - turbo'd '87 C3.2 Guards/Blk, 3.4, 7.5:1 CR, 993SS cams, Borg-Warner S366 turbo @ 1.2-1.5 bar, Treadstone full bay IC, 70mm TB, TiAL F46 WG, HKS 1 1/2" BOV, twin 044 pumps, MicroSquirt AMP'd w/GM smart coilpack, Bilstein coilovers, Tramont replica Speedlines (285's rr, 225's frt), Big Reds frt, 993 rr., tower brace, MOMO wheel |
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08-11-2011, 09:53 AM
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porsher
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If you look at the curves in the AFM link, the shapes are slightly different but none have a .3V step.
This matches my experience.
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86 911 Race Car, with a few 993 bits in the boiler room 79 928 Race Car 88 928 Becoming a Race Car |
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08-11-2011, 09:56 AM
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Chain fence eating turbo
Join Date: Dec 2008
Location: Austin, TX
Posts: 9,138
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On the "1986 AFM map", there is a flat-spot in the first so-many-degrees.
That is where I am confused
__________________
Cory - turbo'd '87 C3.2 Guards/Blk, 3.4, 7.5:1 CR, 993SS cams, Borg-Warner S366 turbo @ 1.2-1.5 bar, Treadstone full bay IC, 70mm TB, TiAL F46 WG, HKS 1 1/2" BOV, twin 044 pumps, MicroSquirt AMP'd w/GM smart coilpack, Bilstein coilovers, Tramont replica Speedlines (285's rr, 225's frt), Big Reds frt, 993 rr., tower brace, MOMO wheel |
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08-11-2011, 09:59 AM
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porsher
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I have measured the actual AFM voltage with the car running at idle (by splicing into the wiring harness.)
The AFM voltage changes a small amount as the idle speed is adjusted.
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86 911 Race Car, with a few 993 bits in the boiler room 79 928 Race Car 88 928 Becoming a Race Car |
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08-11-2011, 10:01 AM
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porsher
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Quote:
look how much the line would deviate for a .3V step
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86 911 Race Car, with a few 993 bits in the boiler room 79 928 Race Car 88 928 Becoming a Race Car |
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08-11-2011, 10:04 AM
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Chain fence eating turbo
Join Date: Dec 2008
Location: Austin, TX
Posts: 9,138
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Quote:
I guess I should look at the values a little more and not the curve.
__________________
Cory - turbo'd '87 C3.2 Guards/Blk, 3.4, 7.5:1 CR, 993SS cams, Borg-Warner S366 turbo @ 1.2-1.5 bar, Treadstone full bay IC, 70mm TB, TiAL F46 WG, HKS 1 1/2" BOV, twin 044 pumps, MicroSquirt AMP'd w/GM smart coilpack, Bilstein coilovers, Tramont replica Speedlines (285's rr, 225's frt), Big Reds frt, 993 rr., tower brace, MOMO wheel |
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08-11-2011, 10:13 AM
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