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Discussion Starter #1
Hi Every one,

I am having a MAF issue that in 2 months my car killed 6 MAFs, i did some diagnostic to check the power supply Feeding the MAF sensor, pin 4 had a stable and constant 5v, pin 2 did not have a 12v instead it is giving 13.8v and keeps jumping from 13 to 14 then 13.6 to 14.1 and not stable, i dont think this is something normal, should it receive a constant 12v ? or what is currently happen is normal ? does the MAF in 2.5 v6 cf3 has a relay or fuse that i can check ?

 

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Pin 2 on the MAF is the battery voltage so it will follow what ever is on the battery.
During charging the battery the alternator generate a voltage that can get upto 14.4V.

The MAF (K41) is protected by Fuse F2 (15A) of the suplementary fuse box.
The Fuel vapour recovery solenoid (L10) and the Lambda sensors (K15, K16, K17, K18) are connected on the same line.
 

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Discussion Starter #4
Pin 2 on the MAF is the battery voltage so it will follow what ever is on the battery.
During charging the battery the alternator generate a voltage that can get upto 14.4V.

The MAF (K41) is protected by Fuse F2 (15A) of the suplementary fuse box.
The Fuel vapour recovery solenoid (L10) and the Lambda sensors (K15, K16, K17, K18) are connected on the same line.
What do you think could kill my MAF, as i understand from you and the diagram that pin 2 is connected with the vapour and the lambda sensors, could this be a short in the circuit that kills my maf ? and if there is a short why only the maf that it is affected, i dont know where to look, can you please help me :( as i have spent a lot of money on replacing mafs


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What make of maf has been fitted?
all are original Bosch F00C 2G2 044
 

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What do you think could kill my MAF, as i understand from you and the diagram that pin 2 is connected with the vapour and the lambda sensors, could this be a short in the circuit that kills my maf ? and if there is a short why only the maf that it is affected, i dont know where to look, can you please help me :( as i have spent a lot of money on replacing mafs
If you had some sort of short-circuit the fuse would have blown.

Electrically I think the only thing that would break the MAF would be an overvoltage.
It could be the vapour solenoid that generate a high voltage spike when it is disabled, but I am not confident that it could be the root cause.

If you have used a KN filter that contained oil it would break the MAF.

When the MAF malfunction what issue do you then see?
Wrong reading of airflow or are the MAF completely dead?
 

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In your other thread where you mentioned this, you said you were using s/h MAFs from old cars. In my experience, pretty much every MAF out of an old car is knackered already. If they work passably well for a shot time, there is not much wrong with your wiring - if there were shorts, you'd be getting weird engine behaviour.

Dirt kills MAFs - oiled filters as above and are you sure the air box is sealed properly?
 

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Discussion Starter #8 (Edited)
If you had some sort of short-circuit the fuse would have blown.

Electrically I think the only thing that would break the MAF would be an overvoltage.
It could be the vapour solenoid that generate a high voltage spike when it is disabled, but I am not confident that it could be the root cause.

If you have used a KN filter that contained oil it would break the MAF.

When the MAF malfunction what issue do you then see?
Wrong reading of airflow or are the MAF completely dead?
i got this issue with all the filters i got it with the stock filter, i got it with the pipercros filter, i dont think its a filter issue :( maybe the over voltage ?, the Maf get killed suddenly,................. usually this happens after an aggressive driving with high revs, and what i feel and see is the car start to struggle and i hear back fire in the exhust then teeet teeet teeet check engine error the maf is dead :angel:, it always always happen after an aggressive run:irked:

In your other thread where you mentioned this, you said you were using s/h MAFs from old cars. In my experience, pretty much every MAF out of an old car is knackered already. If they work passably well for a shot time, there is not much wrong with your wiring - if there were shorts, you'd be getting weird engine behaviour.

Dirt kills MAFs - oiled filters as above and are you sure the air box is sealed properly?
I have used Used MAFs and brand new mafs, the issue is not in the maf it self because logically all of them cant fail the same way which after aggressive driving, now i plunged MAF number 7 and it is the second brand new maf that i installed and i feel it will die too in a week :( ,

i thought there might be a short in the circuit so i cut the ground in pin 3 and plunged it to the battery ground, i dont know if that will save the maf from death or not
 

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Discussion Starter #9
i am thinking can i change the power source in pin 2 ? to another 12v source away from vapour solenoid and lambda sensors ?
 

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when the intake concertina section on mine split, the car would backfire when the engine was under load. It also wouldn't accelerate well tho could still reach good speeds if you eased the throttle rather than planted it. Attempts to repair the split didn't stand up to use and it turned out the top stabiliser bushes were allowing the engine to rock too much, opening the repair up. This eventually led to the MAF failing too, dirt entering the intake, tho it did improve after cleaning it, the performance was off.

I ended up rebuilding the intake completely with silicone hose from the factory airbox to the throttle body, replaced the bushes with poly ones and a new Bosch MAF, its been fine for 2 years since.

Worth checking that your intake hose and any interconnected hoses are in good order, and also if you've any oil entering the intake from the crank breather that connects just ahead of the throttle body as that could contaminate the MAF and cause it to fail.
 

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Discussion Starter #12
when the intake concertina section on mine split, the car would backfire when the engine was under load. It also wouldn't accelerate well tho could still reach good speeds if you eased the throttle rather than planted it. Attempts to repair the split didn't stand up to use and it turned out the top stabiliser bushes were allowing the engine to rock too much, opening the repair up. This eventually led to the MAF failing too, dirt entering the intake, tho it did improve after cleaning it, the performance was off.

I ended up rebuilding the intake completely with silicone hose from the factory airbox to the throttle body, replaced the bushes with poly ones and a new Bosch MAF, its been fine for 2 years since.

Worth checking that your intake hose and any interconnected hoses are in good order, and also if you've any oil entering the intake from the crank breather that connects just ahead of the throttle body as that could contaminate the MAF and cause it to fail.
This is not my case, it would have been so easy if this was my case, as all the intake hoses are fine and in a good shape and my maf is dead not because dirt, it something else either a small short that doesn't blow the fuse or an over voltage



not saying for certain it will help, but it's cheap and can't do any harm (have had good experience in the past preventing lightbulbs blowing) :

You could add an overvoltage protection, either over the battery (normal use), or directly over the 12v supply on the maf, see for example:
Überspannungsschutz für das 12V Bordnetz - Alfa Romeo Shop - Tuning, Styling, Fanartikel und Modellautos
i like this solution so much, so you mean i connect this to pin2 and battery ground right ?
 

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Discussion Starter #14
not saying for certain it will help, but it's cheap and can't do any harm (have had good experience in the past preventing lightbulbs blowing) :

You could add an overvoltage protection, either over the battery (normal use), or directly over the 12v supply on the maf, see for example:
12V overvoltage protection for your car - Alfa Romeo Shop - Tuning, Styling, Fanartikel und Modellautos
Okay until i do the order as it will take some time as i am located in Egypt, is there is any 12v power source that i can connect my maf to other than the current one ? the original maf cost me 100$usd for the maf shipping 10$ usd customs 25$ usd, this is a salary of a normal person here :D i do not want to lose this MAF too as it will be MAF number 7
 
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