Is this the MAF sensor?

[monz87]

Hey guys, I have a 2006 A4 2.0T. I'm going to clean my MAF with the following;

http://www.halfords.com/webapp/wcs/stores/servlet/product_storeId_10001_catalogId_10151_productId_19 5717_langId_-1_categoryId_255223

I don't have any warning lights but my fuel consumption is appauling. Can someone please confirm if that is the MAF in the picture below? I will open it, clean it and put it back without starting the car during the process. Will this bring on any warning lights?

16732

[Deakin]

Yes, that's the MAF sensor.
But why do you think that's the source of your problem?
Have you tried a diagnostic scan?

Deaks

[darich]

How appalling is appalling???
I'm in a quattro and average about 27mpg.....which is worse than my BMW Z4 3.0SE would average.

Might be better posting some figures for comparison before tampering with expensive parts.

[Brycie]

Deffo +1 on that darich, it's easy to upset the MAF by tampering with it from what I've read by other members & that can lead to worse problems.

[monz87]

Oh man, now i'm put off doing it.

Well the car had rubbish fuel economy (12.67 MPG) after I baught it, then it lost boost. I was lucky to find a user with VCDS and had it connected and it came up with the following faults;

008801 - Boost Pressure Control Valve (N249)
012599 - Intake Manifold Runner Control
So I took it back to the dealer who gave it into an Audi dealership, they connected it up to their computers and discovered it was a crankcase breather valve or hose (can't remember which) which was replaced and the car has got the boost back.

But the car still drinks. I put in £30 petrol and it gave me about 80 miles, town driving, and not pushing it hard or anything just normal driving!! Thats 16MPG!

Bare in mind the car has 94,000 miles so I don't know if the MAF has ever been replaced or cleaned, and I read many places that cleaning the MAF can be a good thing...? I don't have any warning lights on though.

[monz87]

Also when the range hits 0 and I put £30 petrol in, the range says 95-100 miles, and it goes down quicker than how many miles i'm actually doing. Even from what the range is telling me it will be about 20MPG, but thats even if it gave me 100 miles! It gave me 80 miles last time! Obviously i'm not driving like a granny just normal driving sometimes pull away at the lights and overtaking as you do, nothing major.

[darich]

Ok....that mog is pretty appalling.
But I'd still advise leaving the MAF alone unless you know what you're doing.

I disconnected mine in the course of replacing headlamp bulbs, but did nothing to it, then reconnected once I'd finished. No problems for me.

What about a fuel leak??

My driving is like yours....not granny like but occasionally pulling hard or overtaking. My car gets between 26-29mpg depending on my style, mood and weather.
With your car I'd expect to achieve AT LEAST what I'm getting ie mid to high 20s. If you're non quattro, then I'd expect closer to 30mpg.

As for MAF.....I'm no expert but the VCDS report you have doesn't mention it, so why tamper with it?
Secondly, I wasn't aware that the MAF ever needed cleaned....not as part of a service plan anyway. Not sure why you think it needs done now.

I'd concentrate on the items listed by VCDS before tampering with MAF sensor.

Best of luck and keep us updated

[monz87]

Do you get that kind of MPG just town driving or a mix? I can achieve close to 30 on a motorway drive about 70ish.
Mine is a non quattro, i'm getting so annoyed now cos I love the car but I can't afford to keep it like this, I just baught the car about a month ago and I'm absolutely skint right about now. It always happens to me!

How much petrol do you usually fill in (pounds) and what does the range say and how many miles do you get?
I read a lot of places that people get the CEL on and it doesnt say anything about the MAF, but once cleaned, problems dissapear.

I know the MAF does get dirty over time, gets greasy, sooty etc and as a result doesnt do accurate readings. You can blast it with electrical contact cleaner, or brake cleaner etc which evaporates.

The reason I say it could be mine is because when I fill up £30 the range straight away says 95-100 miles so thats even before actually driving, the computer is somehow calculating on current conditions the car will give me 100 miles, so could it be from dodgy MAF readings? If it said 150 miles on the range then gave me only 80 actual miles, I woulld more think its a mechanical fault, but the fact that the computer also tells me low miles before moving off, could be from dodgy readings...? Then also incorrectly supplying fuel to the car based on innacurate readings which result in poor fuel consumption.

I would love to see if anyone has actually done this.

[darich]

My normal driving is around 75-80% on b roads and motorways so I'm normally cruising along at between 50 and 70mph. Generally cruise much quicker than that but occasionally accelerate to overtake. My driving, considering the car I have, is probably quite slow.

I normally run it quite low - often the fuel light comes on. Then fill it to the brim. Mileage and volume entered into smartphone app and mpg calculated. I ignore the DIS. Tank capacity as far as I remember is around 61 litres. so when I put in 50-55plus litres, I'm typically between £75 and 80. That'll last me around 350miles.
From my app here are my numbers over 7426miles (14months)
litres per fill up - 52.33
miles per fill up - 322.87
£s per fill up - £69
They're averaged so you can see I typically get 322miles out of 52litres.

If I was to put in £30 that's a bit less than half so I'd expect somewhere around 140-150miles...maybe slightly less.

I'd be very wary of accepting anything the DIS says regarding fuel use and economy unless you get it calibrated using VCDS. My average mpg according to it, is around 30.7mpg.....so it's around 10%high.

I always thought the range shown in DIS was calculated from the last 20miles of driving.....so if you're being shown 95-100 miles then it's based on the last 2omiles or so. But if you have a problem, then that's obviously included in those figures so they're low.

Next time you go for a run.....check your brakes.....are they binding? even slightly?
fuel leak? even a tiny one??
roof bars/roof rack?
tyre pressures?
wheel alignment?
What's the "intake manifold runner control"? if VCDS found an issue there get that sorted.
Check plugs....very sooty? could be too rich which MAY indicate problem with MAF.

Any tampering with the MAF could leave your thirsty car immobile completely - best leaving that to others who know more.

[monz87]

Well considering your driving is mainly on the motorway and cruising most of the time at an efficient speed, I can't really compare. Your calculation of 140-150 miles for £30 petrol seems to be about right, as I would expect about just over 100 miles town driving for the same amount of fuel. But obviously I am not getting that.

I know the DIS is misleading, the figures I gave you are all calculated via the internet, I put the figures into an MPG calculator and put in the miles given, price per lite etc. The only thing I rely on, on the DIS is the range, i.e. when it's 0, I refill.

I don't have a roof rack, tyre pressure seem to be ok, wheel alignment is ok I think, doubt a fuel leak otherwise it would get more empty the longer it was parked, right?
I don't think the brakes are binding either, I guess you mean touching the disk slightly? Even all those things I doubt will make huge difference.

I have messaged the VCDS user, hopefully he will let me use it again. I will see what the log shows this time round.
I'm hoping to get someone here comment about the MAF.

[jdp1962]

I don't think the brakes are binding either, I guess you mean touching the disk slightly? Even all those things I doubt will make huge difference.

Even the slightest drag on the brakes would cause a big increase in fuel consumption


I'm hoping to get someone here comment about the MAF.

People have commented on the MAF. They've suggested you leave it well alone. Don't fall into the trap of only hearing what you want to hear.

[darich]

wheel alignment is ok I think, doubt a fuel leak otherwise it would get more empty the longer it was parked, right?
I don't think the brakes are binding either, I guess you mean touching the disk slightly? Even all those things I doubt will make huge difference.

I have messaged the VCDS user, hopefully he will let me use it again. I will see what the log shows this time round.
I'm hoping to get someone here comment about the MAF.

Ok..........
I suggested
"Next time you go for a run.....check your brakes.....are they binding? even slightly?
fuel leak? even a tiny one??
roof bars/roof rack?
tyre pressures (http://shop.ebay.co.uk/?&_nkw=tyre+pressures)?
wheel alignment?
What's the "intake manifold runner control"? if VCDS found an issue there get that sorted.
Check plugs....very sooty? could be too rich which MAY indicate problem with MAF."

All you've confirmed is that you have no roof rack.
you "think" your wheel alignment is ok - unless you're 100% certain, then get it checked.
you think the fuel level will drop when parked if you have a leak....but what if it's a location that might only leak when running???
Have you checked the "intake manifold runner control"? that you previously mentioned?
Have you checked your plugs for sooty deposits?

there's a reasonable list of things you can check yourself....why do you seem intent on playing the MAF?

you have a few choices.
1 - check everything above and see how you get on.
2 - take the car to a specialist and get THEM to check the MAF.
3 - try it yourself. you might save an hour or so of labour time at a garage....but it might cost you several times that to buy a repalcement if you damage it.

[monz87]

Ok..........
I suggested
"Next time you go for a run.....check your brakes.....are they binding? even slightly?
fuel leak? even a tiny one??
roof bars/roof rack?
tyre pressures (http://shop.ebay.co.uk/?&_nkw=tyre+pressures)?
wheel alignment?
What's the "intake manifold runner control"? if VCDS found an issue there get that sorted.
Check plugs....very sooty? could be too rich which MAY indicate problem with MAF."

All you've confirmed is that you have no roof rack.
you "think" your wheel alignment is ok - unless you're 100% certain, then get it checked.
you think the fuel level will drop when parked if you have a leak....but what if it's a location that might only leak when running???
Have you checked the "intake manifold runner control"? that you previously mentioned?
Have you checked your plugs for sooty deposits?

there's a reasonable list of things you can check yourself....why do you seem intent on playing the MAF?

you have a few choices.
1 - check everything above and see how you get on.
2 - take the car to a specialist and get THEM to check the MAF.
3 - try it yourself. you might save an hour or so of labour time at a garage....but it might cost you several times that to buy a repalcement if you damage it.

Right, I don't wanna sound like a novice, but, how can I actually check if the brakes are binding?
How can I check if the plugs are sooty, can you just take them out and check and put them back? I wouldn't know where to start.
Do you know what the recommeded tyre pressure is for 18 inch wheels?

I know you advise me agaist cleaning the MAF but until I do it I will keep thinking it could be that, if I mess it up I will kick myself but I will know.

After the VCDS came up with those problems it did go to Audi and they replaced the cranckcase breather valve/hose so maybe it was related to that. I'm sure they would have picked up any other faults, unless the dealer hid it from me, as they sent it to Audi not me.

I think I need to get it on the VCDS again, I am waiting on the guy I used last time, hopefully he gets back to me.

[monz87]

Come to think of it, a couple of times when I drove it in sport mode to race someone, I noticed when slowing down a burning type smell, what could this mean? The car does have new discs and pads on the front.

[darich]

When brakes are operated they get warm......so if your brakes are binding, then they'll be warm after driving...I mean prob too warm to touch, so don't get yourself burned!!
Go for a drive.....normal driving. A few miles. Then when you get back home if any of your wheels feel warmer than they should then you have a binding brake. If you don't know how warm "warmer than usual" is, then go for a drive in another car and do the same.
If your brakes are binding, you may well feel the heat before you get too close to the wheel.
And if your brakes have just been done and and smell burning.......didn't that make you think to have someone look at them?

Plugs.....yes it's as simple as taking them out and seeing if they're covered in black sooty stuff....if so it means you're burning too much fuel or running very rich. Neither is good. Admittedly, taking the plugs out requires a plug key and probably some mechanical competence....I'd be unsure of that one myself, but on the other hand, you don't need to run a garage to be able to do it. I'm sure you'll know someone who can pull a spark plug.

tyre pressure isn't determined by wheel size....it's more tyre size. Check the door jamb and see what it says. If you're running a standard size wheel and tyre it'll tell you there and in the manual.

Just for information........the MAF is over £100 just to buy the part.....that would be enough to make me leave it to someone else.

[monz87]

Well I only noticed the burn smell twice when I drove hard, don't know if it was the smell of fresh brakes and discs maybe a bit of oil in there or something, brakes were quite squeaky not so much now. Or was it something else, don't know, if I notice more often then definetely have to get them checked out. I haven't really had it any other time.

When you say the wheel will be hot, do you mean the pad itself or disc or the whole wheel?

[jdp1962]

Well I only noticed the burn smell twice when I drove hard, don't know if it was the smell of fresh brakes and discs maybe a bit of oil in there or something, brakes were quite squeaky not so much now. Or was it something else, don't know, if I notice more often then definetely have to get them checked out. I haven't really had it any other time.

When you say the wheel will be hot, do you mean the pad itself or disc or the whole wheel?
The whole wheel. The heat generated by the binding components will quickly transfer itself to the wheel.

[darich]

As above....everything will be hot. disc, pad, wheel, everything in the area.

But if it is binding, you won't be able to tell which parts are hot because the whole area will be warm....you'll easy feel it.

And check all 4 wheels

[monz87]

Right, so today after several hours on and off driving, I came back home, turned the car fully off, then inspected the brakes/wheels for binding.

Note: Before I picked my car up, just over a month ago, the dealer arranged new discs and pads to the front.

The front two discs were really hot, couldn't constantly touch them, would burn my fingers, but rest of the wheel is not really hot, just little warm I guess.

Rear discs are slightly warm, nothing like the front two.

However, I did notice, that both rear pads are touching the discs parallel to each other.
Both front pads, seem to be at an angle, one edge touching the disc, and the other edge not touching the disc, not parallel, see pictures below;


Front left wheel (passengers side):
You can clearly see the pad is not parallel with the disc and part of it is touching but most of it is not, reflection on the disc also shows this.
16789


Front right wheel (drivers side):
Again same as above.
16790


Rear passengers side wheel:
This pad is all touching and parallel to the disc.
16791


Rear drivers side wheel:
This pad is also all touching and parallel to the disc.
16792


What do you guys think??

[Alan G H]

Those pictures show the pads are OK. New pads have the end of the lining material chamfered off, you will not get full contact till the pads are part worn.

[monz87]

Those pictures show the pads are OK. New pads have the end of the lining material chamfered off, you will not get full contact till the pads are part worn.

Really, so even though the front pads look fitted on bent, they are ok? And some of it is scoring the disc, this is ok?

And the rear pads are proper touching the discs, that is ok?

Then what is binding?

[zollaf]

those pads are sitting fine. binding is when a caliper is tight and holds the brakes on whilst driving. the front brakes will get a lot hotter than the rears in normal use, since 80 odd % of braking is done by the front. right, jack each wheel up in turn. have an assistant sit in the car and apply the footbrake. try to turn the wheel. you can't, cos the brake is on. keep trying to turn it, then get assistant to release the pedal. you should instantly feel the wheel turn. if it does, brakes are fine and not binding. test the wheels for excess heat after a long run where the brakes have been used only very very gently or they all heat up so a binding one will be only as warm as the others.

[monz87]

I jacked the car up on both sides, got my brother to keep the brakes pressed, wheels locked then on brake release right wheel turns fine, little stiff but ok. On the left side it turns, but every quarter turn I can feel a bit of grindy friction. Wheel turns fine but I can feel some sort of rubbing every quarter turn or so.