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JohnJL JohnJL is offline
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Join Date: Jan 2005
Location: Toronto, Ontario
Posts: 4,767
Quote:
Originally Posted by 72911 View Post
Here is a quote from the Megamanual on grounding your sensors. They should all go to the same place (engine block) not the battery.

"The main grounds from pins #8, 9, 10, 11,& 18 go to one spot on the engine block. Do not ground them at physically separated locations, and do not use a single fat wire for this. Instead run separate wires from the pins all the way to the ground spot.
Pin #19 is the sensor ground. If you have two wire CLT and IAT sensors, their grounds (and the TPS ground) should run back to the DB37's pin #19 to reduce the potential for noise in the sensor signals."
Thanks for this, I originally ran the engine block ground cable to the firewall-side of a groundbolt. On the cabin-side I ran each of those ground wired separately as instructed to the same groundbolt. I get 0ohm resistance from the engine to the groundbolt. My tuner then suggested also running a ground from the battery to that same groundbolt, which I did. None of these changes made a difference in the voltage fluctuations.


Then I switched in a standard lead-acid battery...no change in the voltage fluctuations.
Then I switched in another fan/alternator assembly...no change in the voltage fluctuations...

Anyone see strange voltage fluctuations on megasquirt? I seem to have eliminated the battery and the alternator as sources of the voltage swings. BTW this whole time my fluke multimeter shows a solid 13.6v while running. Its only megasquirt logs that show that weirf voltage swinging.
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Old 05-30-2017, 08:18 PM
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