Could my MAF be failing?

micky 32

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Oct 30, 2003
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Longford, Ireland
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Lately my car in third gear seems to be lacking something, especially up an incline, i feel it's holding back, felt like i was missing some horses. It then gradually came back beyond 4k rpm.

I was doing logs tonight and as i was logging the holding back came back again in third gear.

Checked the logs and the boost was perfect so it can't be a boost problem. I checked my MAF reading and usually when it is at full boost it reads 1249.5 mg but when it was holding back it dropped to 901mg at full boost

So is my MAF failing??
 

dmjw01

Upstanding Member
Jul 28, 2005
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Woking, UK
www.dmjwilliams.co.uk
Try unplugging the MAF, and whilst holding the little tab slide it in and out several times, then push it back to its normal position.

I'm finding that my car benefits from fiddling with the MAF connector once a week or so. This is despite applying dielectric grease to the connector. Believe me - fiddling with the connector like this makes it drive like a dream for a week or so. And yes, the biggest benefit is at low RPM.

When we get a decent dry day, I'm planning to squirt the insides of that connector with contact cleaner and clean it as thoroughly as I can, fill it with a hugely generous dose of dielectric grease, then seal it with insulating tape to exclude air.

There's no doubt in my mind that the quality of that connection can make or break the performance of the engine.
 

golisago

Guest
I will try unplgging and plugging the connection to the maf sensor , but whats this dielectric grease , could i get some from Maplins if its an electrical type of item.
 

dmjw01

Upstanding Member
Jul 28, 2005
442
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Woking, UK
www.dmjwilliams.co.uk
Dielectric grease is a non-conductive grease that improves the quality of an electrical connection. That sounds like a contradiction, but the idea is that it prevents the minute amount of arcing that you get, even at low voltages. Have a read of this sticky thread for more info.

I don't know if Maplin sell it, but it is the sort of thing they should have.

To be honest, I'm uncertain whether the dielectric grease makes a real difference. But there's no doubt that disturbing that connector can make a dramatic difference - probably by scraping away a layer of oxide that's making a bad contact.

Getting it nice and clean, then filling it with dielectric grease, should exclude air - especially if you then tape it up with insulating tape which might also help to dampen any vibration. That's my theory anyway - I plan to try it and see if it works!
 

muddyboots

Still hanging around
Oct 16, 2002
5,739
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Lately my car in third gear seems to be lacking something, especially up an incline, i feel it's holding back, felt like i was missing some horses. It then gradually came back beyond 4k rpm.
Micky

Mine's doing the same, feels flat until around 4k rpm then seems to come alive.

I did some logging a little while ago and didn't see anything amiss, might have to have another go and look more closely. I reckon I might have a small boost leak somewhere or maybe a vacuum leak...
 

sssstew

Editing your spelling
Dielectric grease is a non-conductive grease that improves the quality of an electrical connection. That sounds like a contradiction, but the idea is that it prevents the minute amount of arcing that you get, even at low voltages. Have a read of this sticky thread for more info.

I don't know if Maplin sell it, but it is the sort of thing they should have.

To be honest, I'm uncertain whether the dielectric grease makes a real difference. But there's no doubt that disturbing that connector can make a dramatic difference - probably by scraping away a layer of oxide that's making a bad contact.

Getting it nice and clean, then filling it with dielectric grease, should exclude air - especially if you then tape it up with insulating tape which might also help to dampen any vibration. That's my theory anyway - I plan to try it and see if it works!


yes im going to give this a try as recently it feels like my turbo is getting laggy again, like it did before i used the grease.
 

sssstew

Editing your spelling
Lately my car in third gear seems to be lacking something, especially up an incline, i feel it's holding back, felt like i was missing some horses. It then gradually came back beyond 4k rpm.

I was doing logs tonight and as i was logging the holding back came back again in third gear.

Checked the logs and the boost was perfect so it can't be a boost problem. I checked my MAF reading and usually when it is at full boost it reads 1249.5 mg but when it was holding back it dropped to 901mg at full boost

So is my MAF failing??

what was the requested vs actual for the MAF?
 

micky 32

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Oct 30, 2003
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Longford, Ireland
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Requested always says 850 regardless but on full bore should read 1249.5mg actual. However something has come to light thats making me think my MAF might not be fooked...

I have been playing around with settings and we increased my boost pressure to 2bar to experiment. It's when my car is set a 2bar it starts to lose power and give the bad MAF reading! So this points to one thing, the OEM airbox is too restricted to run over 1.85bar so what must be happening is that when i run 2 bar it's causing a vacuum in the airbox or the air isn't able to keep up beyond the filter to flow 2bar!

Any suggestions for good breathing? Are induction kits awful on TDI's? Any suggestions?
 
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