MAF Sensor Ground Wires - which one to use?
Thread Starter
Safety Car
Joined: Sep 2003
Posts: 3,599
Likes: 24
From: Orange County NY
St. Jude Donor '10-'11-'12-'13
MAF Sensor Ground Wires - which one to use?
I have the LM1 Air/Fuel meter with the RPM cable (used for data logging). I want to data log the Mass Air Flow sensor voltage (0-5 volts) that the ECM sees to determine air flow. When hooking up any sensor information to the RPM cable, you need to have a signal wire (0-5 volts) and a ground wire from the sensor for the most accurate readings.
Car is an '87 vette. The MAF sensor has 5 wires going to it. There is a 12 volt feed from the power relay, another power feed from the burn off relay, a signal wire (0-5 volts, which I will be hooking up to the RPM cable), and TWO ground wires. One is labeled as a "System Ground" (which looks like it is part of the engine ground loop) and the other is labeled as an "Analog Ground", which seems to just go to the ECM.
My question is, which one of these ground wires should I use for the connection? Does it matter? I can't tell what the difference between the two ground wires is from my FSM.
Thanks!
Car is an '87 vette. The MAF sensor has 5 wires going to it. There is a 12 volt feed from the power relay, another power feed from the burn off relay, a signal wire (0-5 volts, which I will be hooking up to the RPM cable), and TWO ground wires. One is labeled as a "System Ground" (which looks like it is part of the engine ground loop) and the other is labeled as an "Analog Ground", which seems to just go to the ECM.
My question is, which one of these ground wires should I use for the connection? Does it matter? I can't tell what the difference between the two ground wires is from my FSM.
Thanks!
Melting Slicks
Joined: May 2007
Posts: 2,382
Likes: 2
From: Kathleen FL
Correct me if I'm wrong, but isn't a ground is a ground, aka negative the negative post on the battery terminal? I'd think its would be better to choose the more stable ground for more accurate readings. 
Thread Starter
Safety Car
Joined: Sep 2003
Posts: 3,599
Likes: 24
From: Orange County NY
St. Jude Donor '10-'11-'12-'13
That's what I intend to do - hook it up to the ground wire that the FSM shows as being the "System Ground". I'll hook it up tonight, try some data logging tomorrow, and post up the results.
