faulty maf. how to check?

[bub2006]

I have tried searching but can't find what pins to put a multi meter to and if to have the engine at idle or being revved. Reason I ask is my car still has a slight mis on acceleration but I haven't the funds to get the codes read. I asked local garage and he mentioned that I have a bit of grey smoke from exhaust which indicates over fueling and there fire maf us reading wrong. Any help and clarification greatly appreciated

 

[Dieselman]

Pin-4 WRT Gnd.

Expect ~2v at idle rising to ~4.8v at full revs.

 

[bub2006]

Can you put that into laymans terms please? Which way do I count the pins and use a common earth? Ie engine or a nut?

 

[Dieselman]

The pins are marked, use any metal as Gnd.

 

[bub2006]

Ok thanks. I know the plug has to be connected. If the values are higher or lower it means its time for replacement? If I can self diagnose this then at least it narrows things down. By full revs is that ok at 4k rpm as that's what it revs to in park.

 

[Dieselman]

Do it while driving as you need full revs.
If it is duff the reading will be low, probably peaking at ~3v.

 

[bub2006]

How is it possible to do it while driving? Even holding the box in lower gears where I live is tricky to get it to the redline.