Mass Air Flow Rate

[ncrawshaw]

Hi,
I have a 2002 A6 2.5 tdi (120,000 miles) which is exhibiting the symptoms of a faulty MAF sensor - hesitancy, intermittently jerky on acceleration. I have checked for fault codes stored in the ECU but there are non. I have an app. on the phone which checks loads of parameters in the car. It measures the mass air flow in grams/sec as detected by the ECU. It seems a low reading but I don't know what it should be - any ideas please?

[TurboSteve]

at idle with egr working properly approx 200mg/str.
at idle with egr deleted/blanked approx 400mg/str.
accelerating with little throttle and little or no boost 550mg/str +/-100mg
hard acceleration with lots of boost approx 800 - 900 mg/str.

I have had similar issues!!

[ncrawshaw]

Thanks Steve, I'll check out those readings. Did you end up replacing the MAF Sensor or cleaning it?

[Adam Watson]

What's the app and how does it work?

[ncrawshaw]

Its called Torque and is downloaded onto an HTC phone. You get a plug in bluetooth transmitter that fits the OBC socket on the car. The plugs cost about £15 on e-bay. The app gives you fault codes and loads of other engine data from the ECU.

[TurboSteve]

i replaced what i now believe was a perfectly servicable MAF, twice!!. once with a Pierburg, once with a Hitatchi. the Hitatchi ones used on the high end models are extremely reliable. I have my doubts about the cleaning method - i see many dodgy MAFs on various make vehicles, and the only proper cure has been a new unit every time.

I have an almost new (less than 400 miles), Audi original one for sale in it's Audi box if you need one. It won't be cheap, but much cheaper than the dealer!! check yr part number and i can see if it's the same first tho.

Turned out my problem was a lazy turbo. cost me a fortune in sensors before actually condeming the turbocharger. A really wierd symptom that I (or any of my local specialists) have never seen before.

[Adam Watson]

Glad you got it sorted.
Shame I've got an iPhone, not an android. I've been looking at the iPhone versions of OBDII apps. A chance to indulge my car and technology geek