MAP sensor not seated proper

mistryn · 05-20-2013, 06:42 AM

The manifold absolute pressure sensor is located on the inlet manifold and is held on/in via a rubber grommet like a push fit.

This time last year I had an issue with hesitancy at low revs and I was advised to change the MAP sensor and grommet (which I did) and partly solved the problem

However I was checking my car for fault codes and 41aa boost pressure too high came up which was the same code related to MAP sensor last year.

I had a look at the sensor and feels very loose inside the grommet so not sure if it is making a tight seal -

Would I be able to use something like gasket/silicone sealent to seal the grommet/sensor in place? or would this not be advisiable?

MERLIN335i · 05-20-2013, 07:09 AM

Quote:

Originally Posted by mistryn

Would I be able to use something like gasket/silicone sealent to seal the grommet/sensor in place? or would this not be advisiable?

Most silicone sealants are NOT fuel-proof, so not advisable, unless you can find one that is, they do exist, but expensive.

doughboy · 05-20-2013, 07:13 AM

If its like the 335i one, its possible for the o-ring to get trapped or dislodged and not seal properly.

When you fitted it did you put a little light oil on it so the sensor & o-ring would slide in without getting 'nipped'?

If not, I'd just get another o-ring and re-fit it.

External sealants etc are always just a bodge, avoid, especially on a pressure system.

mistryn · 05-20-2013, 11:23 AM

BMW replaced it last year for me so I wouldnt know if they put a little bit of oil, but wiggling it around it does feel loose - surely the rubber grommet doesnt break down that fast?

I may just take it back out and clean sensor with electrical contact spray and refit - will order a new grommet tommorow

thanks for the heads up on using silicone sealent i wont use that

mistryn · 05-20-2013, 12:56 PM

Had a look earlier on took the sensor out, I had to use a screwdriver to lever it out so it was seated in. The sensor was slightly covered in oil so used a switch cleaner (tip dont poke a pin in the hole

) as this can damage the sensor, checked the grommet which was fine - re fitted, made sure i pushed it in fully. There was some grease around the grommet so I presume BMW did use some

cleared the the 41aa/41ab code and took it for a drive and can definatly notices the improvement - no hesitancy at low revs

05-20-2013, 06:42 AM	#1
mistryn Colonel 147 Rep 2,048 Posts Drives: BMW 335D Join Date: Oct 2011 Location: Mids iTrader: (8)	MAP sensor not seated proper The manifold absolute pressure sensor is located on the inlet manifold and is held on/in via a rubber grommet like a push fit. This time last year I had an issue with hesitancy at low revs and I was advised to change the MAP sensor and grommet (which I did) and partly solved the problem However I was checking my car for fault codes and 41aa boost pressure too high came up which was the same code related to MAP sensor last year. I had a look at the sensor and feels very loose inside the grommet so not sure if it is making a tight seal - Would I be able to use something like gasket/silicone sealent to seal the grommet/sensor in place? or would this not be advisiable?
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05-20-2013, 07:13 AM	#3
doughboy Major General 1545 Rep 8,970 Posts Drives: 2018 M2 Comp 6MT Join Date: Jan 2009 Location: UK iTrader: (2)	If its like the 335i one, its possible for the o-ring to get trapped or dislodged and not seal properly. When you fitted it did you put a little light oil on it so the sensor & o-ring would slide in without getting 'nipped'? If not, I'd just get another o-ring and re-fit it. External sealants etc are always just a bodge, avoid, especially on a pressure system.
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05-20-2013, 11:23 AM	#4
mistryn Colonel 147 Rep 2,048 Posts Drives: BMW 335D Join Date: Oct 2011 Location: Mids iTrader: (8)	BMW replaced it last year for me so I wouldnt know if they put a little bit of oil, but wiggling it around it does feel loose - surely the rubber grommet doesnt break down that fast? I may just take it back out and clean sensor with electrical contact spray and refit - will order a new grommet tommorow thanks for the heads up on using silicone sealent i wont use that
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05-20-2013, 12:56 PM	#5
mistryn Colonel 147 Rep 2,048 Posts Drives: BMW 335D Join Date: Oct 2011 Location: Mids iTrader: (8)	Had a look earlier on took the sensor out, I had to use a screwdriver to lever it out so it was seated in. The sensor was slightly covered in oil so used a switch cleaner (tip dont poke a pin in the hole ) as this can damage the sensor, checked the grommet which was fine - re fitted, made sure i pushed it in fully. There was some grease around the grommet so I presume BMW did use some cleared the the 41aa/41ab code and took it for a drive and can definatly notices the improvement - no hesitancy at low revs
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