North American Turbocoupe Organization



Low VAF voltage
Spooler87 Offline
Posting Freak
#1
Whataresomeof the causes ofa low Voltage situation with the VAM?

Vref is a steady 5 volts, but my output at idle was only .36v when warm. I popped the plug for the air bypass, and i can adjust it down clockwise, ut only to .5 volts at 1k rpm warm.

Not enough intake flow to keep the door open?
All hail Project "Marauder" !
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Spooler87 Offline
Posting Freak
#2
Nobody?

Theories are welcome.....
All hail Project "Marauder" !
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Pete D Offline
Administrator
#3
What kind of mileage on this VAM? Have you tried a known good one as a substitute. I don't know what causes a low voltage signal, but I would try another one.
Pete Dunham


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Spooler87 Offline
Posting Freak
#4
Nobody?

Theories are welcome.....
All hail Project "Marauder" !
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Spooler87 Offline
Posting Freak
#5
This VAM is a remanufactured unit with a whole 30 miles on it. This is the second reman unit we have tried, and we tried 2 known good meters before the remans... all low voltage. They have 5 volta going to them, and the sig return wire has been ohmed and is good, all the way back to the eec.
All hail Project "Marauder" !
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Pete D Offline
Administrator
#6
Have you tried more than one volt meter?
Pete Dunham


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Spooler87 Offline
Posting Freak
#7
Yep! i replaced batteries on my Craftsman meter, same reading. i went to my buddies house and Used his Snap-on meter, and it reads the same.


Could that Exhaust leak between the turbo and manifold cause the turbo to spin slower, therefore causing less flow to travel past the VAM and hence the door shut more than it should be??


We are going to try to fix the leak either Tuesday or Thursday.

If you go back to my other Umpteen million post about this, you can see what has been replaced. i think the Low VAF voltage is a symptom of what is causing my problems, but Im not sure what.
All hail Project "Marauder" !
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Pete D Offline
Administrator
#8
Quote:Could that Exhaust leak between the turbo and manifold cause the turbo to spin slower, therefore causing less flow to travel past the VAM and hence the door shut more than it should be??
IMO At low speed or rpm, I doubt that this has much effect unless it's a big leak.
Pete Dunham


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Bill S. Offline
Senior Member
#9
I doubt the exhaust leak is the problem too. I would fix that and measure the 5v line while its connected to the vam. See if it stays at 5v when its connected.
'88 TC T5
'85 XR7 Roller
Mods on hold pending swap.
Stinger header & mBC on shelf
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JT Offline
Posting Freak
#10
I'm not familiar with your history or why you're here, but a few simple answers are that low VAM voltage at idle can be caused by lower than normal idle (obvious) or a vacuum leak (drawing intake air after the VAM).
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