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.:R32OC Site Contributor
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Discussion Starter · #1 ·
Can any one give me a little bit of info on these please as it's quite a difficult subject to search for as you can't search for a word under 4 letters? I wondered what they actually do (i've gathered they sense the flow rate of the intake air, but why were they introduces as my lupo didn't have one?)? I've also read vague references to them being a common part to go wrong, is it right that they then cause the drive to be less smooth and can cause a stutter? As they're replaceable is it a case of just going to VW and getting another, or can they be cleaned to good effect?

Sorry for all the questions, it's a new one on me!
 

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3,732 Posts
A mass airflow sensor is used to determine the mass of air entering an electronically fuel-injected engine. The air mass information is necessary for the engine control unit to calculate and deliver the correct fuel mass to the engine. Air changes its density as it expands and contracts with temperature and pressure. Air density varies with the vehicle's operating environment, and this is an ideal application for a mass sensor.

There are two common types of mass airflow sensors in usage on petrol engines. They are the vane meter and the hot wire. Neither design employs technology that measures air mass directly. However, with an additional sensor or two, the engine's air mass flow rate can be accurately determined.

Both approaches are used almost exclusively on EFI (electronic fuel injection) engines. Both sensor designs output a 0 - 5.0 volt signal that is proportional to the air mass flow rate, and both sensors have an IAT sensor (intake air temperature) incorporated into their housings.

When a MAF is used in conjunction with an oxygen sensor (O2)sensor, the engine's air/fuel ratio can be controlled very accurately. The MAF sensor provides the open-loop predicted air flow information (the measured air flow) to the engine's Engine control unit (ECU), and the O2S provides closed-loop feedback in order to make minor corrections to the predicted air mass.

:smile:
 
G

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Hi,

the MAF sensor is a common item to go wrong on the VAG engines, they're easily replaceable and aren't that expensive either from VW or from somewhere like EuroCarparts.

Cleaning can sometimes work and give the sensor a bit more life, use alcohol to clean the sensor wire gently with something like a cotton bud.

Induction kits and filters that are oiled often cause MAF sensor problems as the oil can coat the sensor wire which will then cause it to read incorrectly.

Cheers

Neil
 

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.:R32OC Site Contributor
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1,149 Posts
Discussion Starter · #4 ·
Ok i think i might change mine along with the temp sensor. I didn't realise that they were on an exchange basis only at VW, they're not cheap either! Oh well it needs doing i suppose!

Do i need a specific coolant to top up with when i've changed the temp sender, i guess the vw approval number is in the manual?

Thanks for the info guys :top:
 
G

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Hi,

VW only do them complete with the housing, hence the exchange only and the price. You can get the sensors alone from Bosch or an equivalent from Webcon, you just need the part no off the sensor to make sure you get the right one. You'll also need to make sure you've got the right security bit to undo the screws holding the sensor to the housing.

Cheers

Neil

db7 said:
Ok i think i might change mine along with the temp sensor. I didn't realise that they were on an exchange basis only at VW, they're not cheap either! Oh well it needs doing i suppose!

Do i need a specific coolant to top up with when i've changed the temp sender, i guess the vw approval number is in the manual?

Thanks for the info guys :top:
 

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.:R32OC Site Contributor
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1,149 Posts
Discussion Starter · #7 ·
As far as i'm aware my MAF is fine, i had it plugged into vagcom and tested under various conditions and the readings were perfectly fine. I don't have any real stuttering anymore once the car adapted to the software update i had done by vw. I am having issues cold starting at anything below 3c but that doesn't appear to be MAF related :hmmmm2:
 
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