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Old 07-15-2009, 02:19 PM   #1
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Default MAP sensor placement

I'm using a GM 3 Bar MAP sensor in my setup and I've placed it behind the passenger seat because, well, it was easier to wire it in there and run a vacuum line back since I was also installing an olderguy o2 clamp.

So, my question is, is the 8-10ft of vacuum line running to the MAP sensor long enough to cause it to see pressure changes a little bit late? I'm asking because I am having some issues tuning and am getting lean spots when going from part to full throttle on parts on my injector map I know are rich. My theory is that the long vacuum line is causing the MAP sensor to see pressure changes long enough after the engine does that I can't accurately tune in some spots...

Please refrain from the 'Get a MegaSquirt' posts. I will be getting one for any future build but for now I need my piggyback setup to get working right. Thanks!

Last edited by messiahx; 07-15-2009 at 03:34 PM.
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Old 07-15-2009, 02:24 PM   #2
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The pressure change gets there at the speed of sound, or at least the speed of sound in an 8-10ft vacuum tube.

I doubt that this is affecting your tip-in response, and think there are other issues with your tuning that cause you to go lean.

On a MS you can adjust accel enrichments easily. :P
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Old 07-15-2009, 03:35 PM   #3
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Blah. Not the answer I was hoping for. The Emanage has an Acceleration map I will play with to see if that helps. Thanks.
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