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My M535 is running a little rich at the moment and was hoping for some pointers on areas to look at for correction.

The air filter has been replaced as well as exhaust. I am thinking the AFM needs adjustment however I am just not quite sure on how to do it.

Any help would be great

Thanks

Josh

Adjusting the AFM will change the richness, however if you haven't changed it to begin with your only going to be patching a potential problem. I would recommend you find out the real reason why it's running rich.

How you adjust the AFM is you open the black cover and turn the black wheel. This requires you to pry the two little spring arms up and then turn the wheel to the desired position. You only want to move it a few teeth at a time.

JodyStevens wrote:Adjusting the AFM will change the richness, however if you haven't changed it to begin with your only going to be patching a potential problem. I would recommend you find out the real reason why it's running rich.

How you adjust the AFM is you open the black cover and turn the black wheel. This requires you to pry the two little spring arms up and then turn the wheel to the desired position. You only want to move it a few teeth at a time.

Thanks

I am not sure if this has been adjusted by previous owners or not. The car had sat for many years so I am thinking (more so hoping) that all it needs a little adjustment.

Usually you can see if the black cover has been opened, it comes sealed/glued from the factory, to open it you have to work a bit.

To lean it out would I adjust the AFM clockwise or counter clockwise?

I would avoid getting into the AFM unless it's been opened before. From the factory it's sealed with a nice smooth bead of clear silicone.

I would check the CTS and fuel pressure before adjusting a factory sealed AFM. If you need to, mark it first, it's spring loaded and will jump on you sooner than you think when you loosen it for adjustment. Then you would increase spring tension to lean it out. But look elsewhere first.

It's more of a tighter flap vs a looser flap. A tighter flap will let less air in making it run rich while a loose flap will make it run lean. Adjust accordingly. You'll know when you get it to the right spot because it will run perfect(ideally).

JodyStevens wrote:It's more of a tighter flap vs a looser flap. A tighter flap will let less air in making it run rich while a loose flap will make it run lean. Adjust accordingly. You'll know when you get it to the right spot because it will run perfect(ideally).

No, it doesn't work that way. It's measuring the air going in, not opening a valve. Tighter means it thinks less air is flowing since it's moving the flap less, hence it will be leaner.

Regardless of the way it works. Adjust it carefully 1-2 teeth at a time not letting the wheel slip. I've slipped them and you can get it back to its correct spot with a bit of trial and error. The units are laser precision from factory(obviously over time things wear) and usually don't need to be adjusted. Try tightening it and if that doesn't work, loosen it.

What's a CTS ?

Computer Throttle Switch. Central Timing Screw. Colorado Theater Society. How many three letter company names and acronyms can there be before switching to four ? Is there an alphabetized list starting with the American Automobile Club ?

Coolant Temperature Sensor.