What is the ground value of the MAF?

[wawa]

Hey all

Long story short. Lots of problems with the 2000 boxster S. My mecanic work a lots on it and repair everything except one trouble.

Felt like MAF was defect, but he find out that the ground was spiking. So he start investigating the wiring but the trouble stop before he could find out whats going on.

He told me if it start again, I got to check the ground at MAF connections and ECU connection to determine if it's the wiring or the ECU ground generating that is bad.

I am zero in electronic so I will ask someone close to measure ground (mecanic is 300km from here). So what is the value we should read?

Thanks
Chris