Can the MAP sensor get damaged by touching it with cloth?

Sylvester

Active Member
Hi guys, I've cleaned the MAP sensor with dry cotton pads and now I've read it, the INSIDE (2 wires with red bit on top) of the sensor should not be touched, which I did, just sprayed on with "electric contact cleaner", and only the outside should be wiped.

Right pic before cleaning. So if cleaning would've helped the EML code I've been trying to sort out, now I touched the red bit too, which might've damaged the MAP sensor either way.

Anyone knows about this? Can the MAP still be saved, by spraying more cleaner on ir to clean the fingerprint or whatever, or I need a new one?
Thanks.
 

Attachments

  • Screenshot_2021-09-17-18-08-43.png
    Screenshot_2021-09-17-18-08-43.png
    1.1 MB · Views: 54
Last edited:

spike

Member
Just been on a Google MAF sensor training course to understand the basics of how the sensor works
I think the red tip is a flexible silicone chip which varies the output signal voltage depending how much it expands or contracts as the manifold pressure changes.
It's no doubt very delicate so the 'don't touch' warning is probably to prevent people from damaging the membrane by over zealous cleaning.
I don't think it relates to greasy 'fingerprint' deposits damaging it as they can do on halogen bulbs
A basic check would be to read the MAP pressure from cold with the engine switched off. It should be the same as the barometric air pressure.
VCDS is the ideal tool for this.

Cheers Spike
 

Sylvester

Active Member
Just been on a Google MAF sensor training course to understand the basics of how the sensor works
I think the red tip is a flexible silicone chip which varies the output signal voltage depending how much it expands or contracts as the manifold pressure changes.
It's no doubt very delicate so the 'don't touch' warning is probably to prevent people from damaging the membrane by over zealous cleaning.
I don't think it relates to greasy 'fingerprint' deposits damaging it as they can do on halogen bulbs
A basic check would be to read the MAP pressure from cold with the engine switched off. It should be the same as the barometric air pressure.
VCDS is the ideal tool for this.

Cheers Spike
This is great Spike, might be just what I needed, I've found this website so I'll leave link for future references. Thanks a lot!

 
Last edited:

Sylvester

Active Member
WHAT IS GOING ON?!...according to the infos I've gathered:

FACTORY MAP sensor values, with engine off but ignition on, should be around 1000.
Mine is between 1005-1009. (GOOD!)

FACTORY Idle speed should be same, around 1000.
BUT during my idle, very rough, it moves between 411-480! (NOT GOOD!)

FACTORY under load should be 1800-2400.
BUT during my acceleration, it goes maximum 650! Even goes as low as 180, when I let the gas go! 10x lower than should be! (NOT GOOD AT ALL!)

QUESTION: I've fixed every tiny cracks I just saw on the breather hoses, So shouldn't be any vacuum leak, that leaves only faulty MAP sensor? Thanks.
 

Attachments

  • Screenshot_2021-09-17-23-16-35.png
    Screenshot_2021-09-17-23-16-35.png
    1.5 MB · Views: 36
Last edited:

spike

Member
Think guide is for TDi turbocharged engines so even at idle with a touch of boost, the manifold pressure will be around atmospheric pressure (1000mbar)

Your petrol engine has a throttle butterfly which blocks of most of the inlet at idle, causing a partial vacuum in the inlet manifold.

Under load the engine is drawing air through a filter and restrictive intake system so even with the throttle butterfly fully open the reading will be less than atmospheric pressure

Can you find similar test data for a NA petrol engine

Cheers Spike
 

Sylvester

Active Member
Think guide is for TDi turbocharged engines so even at idle with a touch of boost, the manifold pressure will be around atmospheric pressure (1000mbar)

Your petrol engine has a throttle butterfly which blocks of most of the inlet at idle, causing a partial vacuum in the inlet manifold.

Under load the engine is drawing air through a filter and restrictive intake system so even with the throttle butterfly fully open the reading will be less than atmospheric pressure

Can you find similar test data for a NA petrol engine

Cheers Spike
I've found a few more tests, but weirdly they all were diesel car tests.
Typical, as soon as I think I get somewhere without spending £££, it actually goes nowhere.
 
Top