This page documents a modification to some of our earliest GM MAF cables that powered the GM MAF off sensor ground provided on the factory MAF connector. Powering the GM MAF directly off the sensor ground produces a voltage offset on all the other sensors connected to sensor ground!
Normally this isn't a big deal. But when you're switching between a GM MAF setup and a speed density setup, this can really cause a problem because the pressure sensor being used to calibrate and then drive the speed density operation can have its output changed when you connect and disconnect the GM MAF sensor!
To correct this problem, we suggest the following modification. It's really very simple. You are just going to power the GM MAF sensor off chassis ground instead of sensor ground.
The process begins by cutting the ground wire on the GM MAF connector. This may be black or grey, depending on which stretch of ribbon cable was used on your particular GM MAF cable.
You'll want to pull the heatshrink and shielding down, away from the GM MAF connector so that (1) you get some extra length on the cut wire and (2) so that the cut (and any exposed wiring fragments) is left protected underneath the heatshrink when you return the shielding to its original position.
The images below illustrate this process.
The next step should be obvious. Just solder an extension wire onto the exposed end of the GM MAF ground wire and run it over to a chassis ground point. We do this with a standard ring terminal as illustrated below. Of course, as always, be sure to heatshrink the solder joint. It would also be a good idea to put a zip-tie around the three wires to the GM MAF connector to provide strain relief for the new wire…