nbuscemi
Samba Member
Joined: May 30, 2009
Posts: 733
Location: Fort Worth, Texas
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 Posted: Sat Nov 10, 2018 3:13 pm Post subject: Grounding sensors through PCM... |
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This is one of those "I should have known better" stories...
Even though I've had a lot of experience with EFI it has always been diagnosing or repairing a factory setup. Replacing the factory carb with a home-brewed fuel injection setup has certainly been a learning experience. Megasquirt specifically instructs to use the PCM ground for all sensors. When I wired up the ECT (engine coolant temp) or in this case Cylinder Head Temp it was after everything else was already in place. Not thinking, I wired the CHT / ECT sensor to the engine ground. For the life of me I couldn't figure out why my engine temp data was so jumpy ( see datalog below)
After connecting the engine temp sensor ground directly to the PCM sensor gorund pin (same as the IAT sensor) there was a world of difference (again, see below)
Nice and smooth!
So take this as freindly advice or something to double check is you are getting erratic sensor signals.
-Nick-
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-Why buy it when you can BUILD it?- |
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