View Full Version : MAF sensor
please could someone explain what this is? BTW, what does MAF stand for?
i have a friend with a completely standard leon 20V SE and he's just had to fork out over £200 for a new MAF sensor. i read somewhere that the MAF sensor was self cleaning, is this right?
how would one know if they had merely a dirty sensor or a broken sensor??
maybe someone could post a pic of where it's located under the bonnet
thanks
ibizacupra
21-10-2003, 15:07
Originally posted by jerry
please could someone explain what this is? BTW, what does MAF stand for?
i have a friend with a completely standard leon 20V SE and he's just had to fork out over £200 for a new MAF sensor. i read somewhere that the MAF sensor was self cleaning, is this right?
how would one know if they had merely a dirty sensor or a broken sensor??
maybe someone could post a pic of where it's located under the bonnet
thanks
Mass Air Flow meter
measures in g/s incoming air into the motor.
dead sensors can bring on engine check light.
dirty ones can lead to erratic performance and flat spots.
cleaning in isopropyl alchohol has been know to resurrect some.
Bill
also i have heard they try and self clean themselves by running extra voltage through to burn off any deposits, and hence burn themselves out.
chriskaven
21-10-2003, 15:55
How exactly do you clean a MAF?
get some electrical contact cleaner (isopropyl alcohol) and take it out and spray with this thoroughly.
Snoopstah
21-10-2003, 19:33
But be aware - the actual sensor is exceptionally delicate (well, it has to accurately detect passing air!)
If you so much as touch the physical sensor, you can probably say goodbye to it.
any idea how much a new one is?
i would hate to think my friend was ripped off...
Shock_Xe
21-10-2003, 22:25
£200 sound about right
agreed. £200 sounds about right.
i read on some forum that if the MAF sensor gets hot (which is quite likely) the fuel mixture will be leaner, and that it's a good idea to insulate the MAF sensor to try and keep it's temp down.
credible or bs?
Shock_Xe
30-10-2003, 21:27
my maf has gone :( but was told 06A-906-461-A is a cheaper alternative to the stock 06A-906-461-D in the 1.8T's,
Might give it a try
max_torque
31-10-2003, 08:01
Originally posted by jerry
i read on some forum that if the MAF sensor gets hot (which is quite likely) the fuel mixture will be leaner, and that it's a good idea to insulate the MAF sensor to try and keep it's temp down.
credible or bs?
thats BS!
the MAF measures MASS air flow, not Volume air flow (that would be a VAF!!) hence as temp increases, air voulme increases, velocity increases (for the same mass flow) which cools the measurement element the same as the cooler air going slower, so you get the same result.
A bigger problem is people who change there airbox for an aftermarket filter. when the MAF installation is calibrated, the airbox/ MAF / inlet pipe is "characterised" and the MAF's voltage output accurately calibrated to actual airflow, taking account of things like eddies, and dead flow areas caused by the airbox and intake geometery. When you stick a different filter on all this goes straight out the window, and is why most modern cars will loose power when you stick an aftermarket filter on them. If you are going to do this, make sure you get as close to the original geometery as possible, ie no extra bends pre or post MAF, same diameter tubing etc.
On every key-on cycle the actual "hot film" element has a significant over current flashed across it, lifting it's temperature and burning off oil deposites etc. But this is only capable of removing small contamination. Over it's life a MAF does "drift" and it's voltage output becomes disproportional to the airflow through it, some of which can be corrected within the ECU initally.
When the MAF fails completely the engine will put on the MIL, and go into FMEM mode, using a back up table to look up the expected airflow at the current rpm, temps, throttle position etc bases on a nominal engine. This will enable you to keep driving, but it really depends on 2 things, how close your car is to a "nominal" one, and how good the bloke who calibrated the table was!
Shock_Xe
31-10-2003, 08:38
so in reality a new MAF re-calibrated should come with induction kits! In an 'Ideal world'
ibizacupra
31-10-2003, 10:08
MAF's have flow straighteners and mesh in front of them to aid laminar flow...
Std airbox has a radius bell on the inlet to the MAF tube... which Dynatwist also has :D Nice little touch to the ally spinning I thought.
Bill