Faulty Map Sensor

[glynnd]

I think my map sensor is faulty, if it is would it lead to a reduction in boost pressure.

 

[aaronbromley]

MAF sensor i think it's known at, i could be wrong, but yeah... these are very common on a Diesel, i had mine replaced at around 30k miles.

 

[Viking]

MAP sensor (Manifold Absolute Pressure).

Yes, faulty map sensor could lead to incorrect boost levels as it wouldn't be reading the actual pressure correctly. If it was over reading, then you'd not have enough actual boost. If it was under reading you'd have overboost.

I have to say that it's not a common failure item. What makes you think it's failing?

 

[glynnd]

Have an intermittent loss of performance.
Did a check with vag com with no faults found, however the reading from the map sensor is 82 at idle when its minimum reading is 88
I have replaced the maf and done all the obvious checks but the problem persists
Glynn

 

[sssstew]

Glynn, have you done some logging with VAG COM? logged MAP and Maf? requested vs actual....

 

[muddyboots]

Have an intermittent loss of performance.
Did a check with vag com with no faults found, however the reading from the map sensor is 82 at idle when its minimum reading is 88
I have replaced the maf and done all the obvious checks but the problem persists
Glynn

What units are we talking about, when you say 82 & 88 ?

Thought the MAP readings were usually in millibars, so you'd normally expect so see 900-1000 as a minimum (which is atmospheric pressure) and then anything up to 2500-2700 at full boost.

 

[muddyboots]

MAF sensor i think it's known at, i could be wrong, but yeah... these are very common on a Diesel, i had mine replaced at around 30k miles.

MAF = Mass Air Flow sensor (quite a common failure)

MAP = Manifold Absolute Pressure sensor, or boost pressure sensor.

 

[glynnd]

Going to do the logging on Sunday to find out if it tells me anything
With regard to the values not sure what they are in just know the value is lower than what it should be and yes I am talking about the map sensor or boost pressure sensor.
Glynn