Originally Posted by Bad Noodle
I just got a brand new Denso MAF and tested it:
Looks like this is supposed to happen... so it's not a bad maf. It's that the maf is metal and pin #4 gets grounded through the pipe to the chasis.
NSFW is right, need to isolate the maf. I'll try layering some liquid electrical tape between the maf and the pipe and put some plastic washer on the screws that hold it
What I used was mica insulators used for transistors. Mine are .0025" thick, I used four... one on each side of the MAF's metal plate at each of the two mounting holes. This insulates the MAF sensor from my AEM CAI metal pipe.
While that alone changed things, even more change occured when I put a ground between the AEM CAI tube and the fender... capturing the heat shield in the process, which heretofore was also "floating" due to insulating paint.