The function of the MAF

[Anonymous]

Can anyone tell me the actual function of the MAF. I under stand it measures air flow, but does it therefore directly give feedback to the ECU and adjust accordingly?

My engine is running rich at the moment as my MAF is faulty and I wondered whether this would be cured with the new MAF or whether there was another reason for the richness?

In essence, what's this MAF all about?

[Anonymous]

Here you go matey  :-) :-) :-)

 m http://autorepair.about.com/library/glo ... ef-496.htm m

[Anonymous]

Sweet so it does control the fuel mixture.. which is why my car is running rich. Super!

[Anonymous]

Super dooper - space troooooooper  :-) :-) :-)

So Mr T said yours is knackered then >>?

[mg]

Are you sure you did not knaff it up when you switched it to the Apexi?  Did you damage or are you missing the O ring?  What did you clean it with? It's hard to see what could fail on the MAF as it's quite simple...

[Anonymous]

I just took it out and put it back in again... I didnt see an O ring, that I can think of. Haven't cleaned it yet, MR T said they had, but I'm not sure.. they reckon it's just faulty...

I was pretty careful wehn I removed and replaced it..

[aaronjb]

IIRC the 'hot wire' (that's used to sense airflow) is up inside the plastic part anyway, you can't actually touch it.. The bulbous bit on one side is the air temp (it's a thermistor) sensor - I'm prepared to be corrected on that but I'm pretty certain  s;) s;)

These things can (and do) fail, usually electrically - they live a fairly hard life, really, given how it actually monitors the air mass passing it.

It should definitely have an O-ring, though - without it you won't get a seal, which may well result in unmetered air being drawn in (though that would make you run lean, not rich).

[red_leicester]

Haven't cleaned it yet, MR T said they had, but I'm not sure

They probably meant they wiped the dirt off the plastic housing with a rag   s:wink: :wink: s:wink:  

Aaron is correct in what he says.  IIRC the o-ring is quite a tight fit so it probably didn't fall off when you put the Apexi on.

[Anonymous]

Yeah, I'm sure I'd have noticed if it had... I'm going to get some carb spray and clean it tonight and see what happens. I just wanted to make sure that the MAF controls the richness of the fuel really... so I'm glad that it does!

[aaronjb]

Before you clean it with carb cleaner (since some carb cleaners eat rubber) - remove the O ring  s;) s;)

And then spray up into the hole that's up top inside the.. erm.. dangly bit.

I'm all up with the technical terms today!  s:lol: :lol: s:lol:

[Anonymous]

Hole, ring, dangly bit.. got it.

/feels dirty

[mg]

These things can (and do) fail, usually electrically - they live a fairly hard life, really, given how it actually monitors the air mass passing it.

If I had to guess how the MAF actually works, I would say it determines airflow from measuring the cooling effect of air passing over the thermistor.  The hot wire would be providing a constant heat source.  Would it need an ambient air temp to make the math work?

[Anonymous]

OPERATION:
The hot wire is maintained at 200°C (392°F) above ambient temperature as measured by a constant cold wire. The current required to maintain the temperature of the hot wire is proportional to the air mass flow. The MAF sensor then measures the amount of electrical current required to maintain this temperature difference and converts this value to an analog DC voltage. This output varies directly with the mass air flow rate.

http://autorepair.about.com/library/a/1b/bl499b.htm

[Anonymous]

Sorry for bringing back this thread.
I had fittedthe PPE 2 weeks ago. ever since, the car has been sluggish so it went to the garage. They had a poke around for a while and have just concluded today that it is the MAF sensor that has cracked inside, as well as the seal being broken.
I'm guessing; after reading this thread; that this is feasible?
They have ordered a new one (which won't get here til tuesday[missing all the sun]!!  s:evil: :evil: s:evil:  )
How much are they?

[darrenjuggins]

about £100 to £125 !!!

Cheers

Darren J

[kanujunkie]

IIRC they're around the £90 - £100 mark. It is possible to crack the Maf but they are pretty resilliant. Personally i'd try a new seal which is about £2 and a full reset of the ECU before you buy the MAF itself. The seals on the MAF do disintegrate pretty easily and do require a descent seal

[spit]

Someone posted up that they'd replaced theirs (quite a while ago now).

£95.

*edit: It was Blackmax - link is here*

[edward.carter]

mine failed and the replacement one was £99 (forr warranty direct  s:) s:) )