During MOT AFM would not adjust.

[Stevieabz]

325i Sport 1987, running rich since I got her. Had its first MOT with me the other day and it past. The only problem I saw was when he stuck that c02 sensor or whatever it was in the exhaust and took an alan key to the AFM, he said it's just not adjusting. He took it all the way one way and back. Do I need a new AFM? How can I test this one? Was that pretty much a test telling me I need a new one? Could I try repairing it? Help please guys.

[Speedtouch]

http://www.e30tech.com/forum/showthread.php?t=90205

http://www.r3vlimited.com/board/showthread.php?t=247831

[minesapint]

http://www.e30zone.net/modules.php?name ... c&t=153524

Try this, I'm finding it very informative. (It's a sticky under e30 technical help)

Cheers

[minesapint]

Sorry should have added.

Read the sections on: Air flow meter (AFM) & Adjusting the base idle speed & mixture.

[Brianmoooore]

And another one! DO NOT LET ANYONE ADJUST THE AFM ON AN E30 UNLESS YOU KNOW EXACTLY WHERE IT WAS ORIGINALLY!
MOT testers are used to seeing a progression of scrap passing before them, and most see an E30 as just another clapped out old car. They just don't appreciate what's before them.
The AFM was set correctly at the factory, and never needs adjusting. If the CO figures are wrong, or anywhere near the MOT limits, then there's a fault that needs addressing.
Sorting the fault will not only get your car to pass the emissions test with flying colours, but will pay dividends in terms of MPG and BHP, which will pay for the repairs many times over.

[Stevieabz]

Thank you guys appreciate your help. I will get it out and get a multimeter on it asap.

[Stevieabz]

And another one! DO NOT LET ANYONE ADJUST THE AFM ON AN E30 UNLESS YOU KNOW EXACTLY WHERE IT WAS ORIGINALLY!

I did not know this! And I don't think he did either! As I walked over after seeing the bad reading he was already adjusting it. Where can I get this sorted? Will buying a new one fix the issue. I think I need a new one anyway.. but who's to know if someone has messed with that one in the past.. also will it be set up right for my car? Do 325i Sports have a specific AFM? So many questions

[Brianmoooore]

The 325i Sport uses exactly the same engine as any other E30 325i, and exactly the same AFM. No difference in the engine at all.
Some E30s are fitted with a red plastic cap over the adjustment to deter fiddlers, but in the absence of that, there's no way of telling.
Why do you think you need a new one? In my experience, failure of this part is fairly rare, but it is easy to test with a 6 volt torch battery and a volt meter (see wiki)(probably), and if found to be faulty, can usually be given a new lease of life by adjusting the position of the rotary brush inside.
The only way it can be adjusted is to set it up on a CO meter, once everything else on the engine is as it left the factory.

[Stevieabz]

The only way it can be adjusted is to set it up on a CO meter, once everything else on the engine is as it left the factory.

So the fact that nothing happened when he plugged in the CO meter and adjusted the AFM doesn't necessarily mean its the AFM's fault? I think I need a new one because nothing was happening when he was adjusting, he said "it wont adjust", It stinks of petrol most of the time and the idle is okay but not great.. has big dips and highs sometimes when I put the clutch in whilst driving. I dunno, it doesn't feel great. But like you said it could be something else.