Brakes and MAF sensor.

[DJG]

Have been thinking about brakes for a while, but after the post Christmas credit card bill of doom I decided that I would have to go with OEM.

Took the car to AMD on Friday and they fitted new discs and pads all round (Always enjoy a chat with the other customers while I am there). They also had a general check of hoses, DVs etc. After driving it and seeing that there were weak running error codes they diagnosed a faulty MAF sensor. Was actually pleased with this as had felt the car was a bit off for a while, but Whites couldn't find anything wrong.

Car booked in to Whites today to have the MAF sensor changed under warranty (I hope!) plus a few other things. In reality best I can expect is they agree a warranty claim and have to take it back for the work to be done. Yawn..

Unfortunately I have had problems with the brakes. One of the front pads is dragging on the disc. You can just about hear it, but can make a louder squeal if you just touch the brakes gently. Goes away completely, with a harder prod on the pedal.

Been back to AMD who freed things up [img]images/graemlins/thumbs.gif[/img]

But it has started to do it again [img]images/graemlins/033102bad_1_prv.gif[/img]

Damn nuisance really. AMD a bit of a drive and don't really want to pay an Audi dealer.

Cars don't we love them.
[img]images/graemlins/beerchug.gif[/img]
David

[DJG]

Just heard that Whites have replaced the MAF.

Hopefully I will notice the difference!
[img]images/graemlins/beerchug.gif[/img]
David

[DJG]

Continuing with my one man thread... [img]images/graemlins/wink.gif[/img]

Car's performance seems a lot crisper with the new MAF and quicker in the lower gears.

BUT it is actually slower in top gear roll on.

Bugger! Nothing is straightforward. Anyone have any ideas.

I feel another trip to AMD coming on. They can look at the brakes (again) at the same time.

David

[snbS4]

Sorry to interrupt!! [img]images/graemlins/1syellow1.gif[/img]
I have just had my MAF changed and found that my economy went back down a bit but that the on/off throttle and gear changing was much smoother.
Much nicer drive now and the performance is strong and turbine-like again. [img]images/graemlins/smile.gif[/img]
Prior to that I had the lambda sensors changed and the DV's changed to Forge items. It's only now the MAF has been changed that I no longer have the (touch wood) intermittent loss of power thing at 80 in 4th. Ironic really as I have spent loads of time (and money) trying to fix it. [img]images/graemlins/crazy.gif[/img]
Joys of motoring eh?
Simon [img]images/graemlins/s4anogaro.gif[/img]

[Dippy]

David,

I can't comment on the brakes, but regarding the MAF, remember that it is one of the key sensors which the ECU uses in its map. Because your old MAF was faulty, the values taken from the map would be been wrong. With your new MAF a different set of values will be taken.

I can only assume that for some reason the values with your old MAF resulted in better performance in top gear roll-ons than with the new one. Remember that engine mapping is a balance of many factors and the designer limits performance for good reasons (e.g. long-term reliability). Your stock map is particularly constrained. This means that under exceptional circumstances such as a faulty MAF, it may be possible to increase performance under some circumstances.

This is just theory of course.

It does worry me that MAFs fail so often (Bushy has just had his replaced), and damage can be caused by running a car with a faulty map. Although I'll regularly check my DTCs, I'm inclined to replace the MAF anyway at some point just to be safe.

[DJG]

Hi Dave,

Thanks for that.

Just been out in the car.

Performance in the lower gears actually feels stronger than it ever has. Don't normally try to measure 0-60, as I don't like to strain the clutch, driveshafts etc, but in the wet, pulling away with about 2500 rpm, and with a not too brilliant 1st to 2nd change, I got 5.9s, which I though was OK. So with better driver/conditions I'm sure it would hit the 5.5 to 5.6 it is supposed to do. Actually it seems to have got quicker over the last few hundred miles, so maybe it is adapting (Would have expected the dealer to do a reset).

MAFs really do seem to be a consumable part!
[img]images/graemlins/beerchug.gif[/img]
David

[miketheman2k]

Hi David,

What do you use to measure your 0-60 times? I personally use the 1-elephant-2-elephant... although I sometimes feel it's not as accurate as I would like. [img]images/graemlins/spineyes.gif[/img]

Cheers,

Mike

[wazza]

Hi David,

What do you use to measure your 0-60 times? I personally use the 1-elephant-2-elephant... although I sometimes feel it's not as accurate as I would like. [img]images/graemlins/spineyes.gif[/img]

Cheers,

Mike

I'm not sure that the 1-elephant etc method of timing will get you 5.9s [img]images/graemlins/tongue.gif[/img]

[DJG]

[img]images/graemlins/roflmao.gif[/img] Thanks chaps.

I just have a cheap digital stop watch. Pretty crude, but helpful in judging how the car is performing. Better than counting elephants anyway. [img]images/graemlins/thumbs.gif[/img]

Must say I was quite surprised by the acceleration in first. I think my MAF must have been sick for a while, plus I will admit that I don't normally scream away from the lights. Too old for that [img]images/graemlins/shocked.gif[/img]

David

[daddyjohal]

Sorry to interrupt!! [img]images/graemlins/1syellow1.gif[/img]
I have just had my MAF changed and found that my economy went back down a bit but that the on/off throttle and gear changing was much smoother.

Gear changing? How does that improve with a new MAF then??

[Nige_RS4]

It does worry me that MAFs fail so often (Bushy has just had his replaced), and damage can be caused by running a car with a faulty map. Although I'll regularly check my DTCs, I'm inclined to replace the MAF anyway at some point just to be safe.

It is unlikley that you will ever see any DTC's with a MAF that is failing over a period of time.

I would recommend you keep an eye on the g/s airflow thought the MAF using VAG-COM, so you can see the max values dropping and also keep it clean using 99.99% alcohol [img]images/graemlins/062802drink_prv.gif[/img].

Nige.

[snbS4]

Er, not by the gearlever/box feeling physically any different but in the process of changing gears: when the clutch was depressed, it felt as if the engine lost more power than it should and so when released after selecting the next gear, it sort of hesitated or jolted a bit.
Clearer, I hope? [img]images/graemlins/confused.gif[/img]
Anyway, it is much smoother and better [img]images/graemlins/grin.gif[/img]
Rgds
Simon [img]images/graemlins/s4anogaro.gif[/img]

[Dippy]

It is unlikley that you will ever see any DTC's with a MAF that is failing over a period of time.

I would recommend you keep an eye on the g/s airflow thought the MAF using VAG-COM, so you can see the max values dropping and also keep it clean using 99.99% alcohol [img]images/graemlins/062802drink_prv.gif[/img].

Nige.

Good point. I will do a combination of the two. Last time I checked IIRC it was over 280 g/s which seems healthy.

Not sure I can be bothered cleaning the wire, and besides, based on the fault reports posted here, contamination is not the only failure mode and may not even be the preferred one.