Hi, My Fabia vRS is running a bit flat now and doesnt feel very revvy at the moment. Speaking to one of the lads at work they have had a quick look and maybe thought that it could be a faulty Air Flow Meter, has anyone had one go faulty on their car, I just wondered if the symptoms would be the same?

Cheers, Matt

A quick test is to disconnect the MAF. If it runs better or there is no difference at high loads, then the MAF is faulty. MAFs tend to be past their best after 4-5 years.

edit - incorrect advice, I've misinterpreted somewhere

Edited 7 September, 201114 yr by gavinchappell

I believe that's only true on petrol engines which rely on the MAF for fuelling info (for example the VAG 1.8T), it doesn't work that way on a diesel...

Not true - it works that way for diesels too. That's why it has one!

edit - incorrect advice, I've misinterpreted somewhere

Edited 7 September, 201114 yr by gavinchappell

Sorry, maybe I wasn't clear. I know that when the MAF is plugged in, a diesel EDC ECU will use the input from it to control the fuelling. But I believe that unlike the MED ECUs on the petrols, it lacks a sensible set of "fallback" values that it uses when the MAF is detected as missing. So I've read anyway, may not be true.

No. If the MAF is unplugged, the car will use a default curve and will generally be a bit sluggish, but will run reasonably well. It is however very noticeably slower at high rpm/high load as the ECU limits the top end fueling

e.g. Trying to accelerate from 69 MPH up a hill on a dual carriageway will feel like you're driving into a strong wind.

e.g. Trying to accelerate from 69 MPH up a hill on a dual carriageway will feel like you're driving into a strong wind.

Thats kinda how it feels now to be honest, sometimes it runs fine tho, then the next time it takes ages for the revs to build up, Skoda want the old one plus £92, Eurocarparts will do one for £74

Maybe try cleaning it?

There's a guide here realting to the ibiza but it's the same engine.

http://www.seatcupra.net/forums/showthread.php?t=266773

Phil

Would Vag com pick up a maf fault?

Would Vag com pick up a maf fault?

The best way to see if a MAF is working is to log the MAF requested/actual in VCDS. Drive through the gears at WOT to ensure the EGR is at minimum duty cycle/off.

Never have a VCDS when i ned one lol

Hi, My Fabia vRS is running a bit flat now and doesnt feel very revvy at the moment. Speaking to one of the lads at work they have had a quick look and maybe thought that it could be a faulty Air Flow Meter, has anyone had one go faulty on their car, I just wondered if the symptoms would be the same?

Cheers, Matt

Start with the connector. Disconnect the plug and spray or coat it with silicone dielectric grease.

http://briskoda.net/forums/topic/194314-cage-mod-anyone-tried-this/

^^^ Fuller article. Clean the contacts. Maybe just unplugging and replugging a couple of times may help.

Question: have you had the cambelt done recently?

J.

Hi, yeah I'll try that and see if it works, yeah the cambelt was done last year maybe about 12k ago.

Do they get gradually worse or just go?

Ive been out in it tonight and had a little play, it seems to be at it's worst when you floor the accelerator, when you accelerate gently it's not as bad

Just cleaned mine off with some electrical contact cleaner.

I had noticed it felt a bit flat on the top end.

Seems to have done the trick. Ran ok on the little test run between 2 junctions on the A64

Sent from my HTC Desire using Tapatalk

I Put a new Maf in my car today, (Recon Actualy) the car now pulls better mid range, i reset the MFA and even though i was driving much harder than i normaly would the the MPG was better.

I Put a new Maf in my car today, (Recon Actualy) the car now pulls better mid range, i reset the MFA and even though i was driving much harder than i normaly would the the MPG was better.

To answer your previous question - yes they can degrade slowly over time. It's common for owners not to notice the gradual performance loss and then be surprised when a new MAF is installed.

I believe that's only true on petrol engines which rely on the MAF for fuelling info (for example the VAG 1.8T), it doesn't work that way on a diesel. They do go faulty with surprising regularity though, GSF will do you one for about £60-70 quid plus your old one in exchange (which goes back to Bosch for refurbishment).

This is absolutely untrue, the MAF on a modern turbodiesel is crucial to performance and economy.

The Fabia petrol engines don't even use a MAF, they use a MAP sensor which can't be used on diesels because they don't have throttles.

Sorry, maybe I wasn't clear. I know that when the MAF is plugged in, a diesel EDC ECU will use the input from it to control the fuelling. But I believe that unlike the MED ECUs on the petrols, it lacks a sensible set of "fallback" values that it uses when the MAF is detected as missing. So I've read anyway, may not be true.

Where on earth did you read this ancient wisdom please (wikipedia?), because it really isn't relevant to what we're talking about here.

Nonetheless, reading is good, comprehension needs to be better.

As I said, I know that MAF input is important to fuelling. HOWEVER, when you unplug the MAF, then something must be substituted in its place otherwise you would constantly read zero or open-circuit, which would bugger up fuelling royally. I was originally under the impression (possibly from reading SCN but I can't be sure) that the petrol ECUs had these "safe values" stored for use without a MAF, while diesels didn't. It appears that I was mistaken

However please don't assume that I don't know what a MAF does, I'm fully aware that it forms an important part of the fuel system, but this discussion wasn't necessarily relevant to that as it was about what happens when the MAF is removed

I would say it's absolutely relevant since you started out by giving bad advice based on a false premise.

The MAF is not critical to the engines ability to run like, say, the engine speed sensor, so when the ECU detects a value outside the normal parametric range (i.e. when you disconnect it) the ECU simply forgets what it thought it knew and loads the default or base map so that the engine can continue to be driven. ALL ECU's need to start from a base map which they then dynamically modify into a working map as the ECU learns the parameters of your particular engine/sensor setup.

Nothing needs to be substituted in it's place because that's NOT how the system works gavin.

Fair enough, well there are more people than just me operating under a false assumption then. In my first post (which I'll admit was terribly worded as it gave the impression that the MAF wasn't important at all even when it was plugged in) I did express it as a belief rather than a fact, i.e. I wasn't 100% sure and was offering advice which may turn out to be bad. I also said in the clarification post that it was something I'd read (can't find the source now) and may turn out not to be accurate. So I wouldn't say I was offering bad advice as I never said it was a solid fact, but something to look into

So, do we recon that it might be my MAF that might be buggered after all?

So, do we recon that it might be my MAF that might be buggered after all?

Yes