AAN serious Maf trouble..

[quattrojan]

Hi! I've almost pulled most of my hair out by now to find this problem.

I'm running a GT3071R with all the extras and the first maf didnt last long before one of the threads got torn off... The car ran fine as long as i didnt go into "boost-mode"
Changed the maf and all good. then after about 700 km the car started to act up quite badly. No respons on less then half throttle and stalling and idling like crazy (400-1500rpm) took the maf of to check the threads and all are fine but the car barely starts and stalls every 50 meter when driving. When i disconnect the maf i get the same result as when the other maf lost a thread, smoothily running as long as you dont go into boost. So on with a new MAF again but still the same problem... car wont run with maf plugged in.

No fault codes to find on Vagcom

Anybody got any ideas?

[T2Andy]

Fuel supply maybe

[Acidburn]

which side is the maf on, before or after the turbo?

[prj]

Have you checked your AFR lately? Have you got a wideband kit on your car?
Maybe it's not the MAF but some other physical issue - fuel or ignition related?
When you disconnect the MAF, motronic goes into Alpha-N mode.

But with cars 400hp and over, the stock MAF is not going to last very long. I have a cure for it by using the RS4 MAF, but I would need to map the car on a dyno... or at least on the road.
It's definitely not possible to make a tune over the internet.

[quattrojan]

Its before the turbo. And i know this causes maf's to go faulty due to the preasure and turbulence coming back true there when i go of the throttle. But with this last new maf the car hasn't even been driven yet, just started up and still showing the same problem.....

which side is the maf on, before or after the turbo?

[prj]

I don't recommend moving it after the turbo either... that'll cause all kinds of poor running in different conditions.... and leaning at the top (=boom).
Have you checked AFR when your car starts missing? Fuel pump, fuel pressure etc is all okay? No leaks in the intake?

[prj]

And i know this causes maf's to go faulty due to the preasure and turbulence coming back true there when i go of the throttle.

That should not happen if you have a bypass valve fitted. Check that too...

[quattrojan]

Have you checked your AFR lately? Have you got a wideband kit on your car?
Maybe it's not the MAF but some other physical issue - fuel or ignition related?
When you disconnect the MAF, motronic goes into Alpha-N mode.

.

Yes. i have LC-1 that showed (when maf nr 2 started to fail) 16-18 AFR on easy cruising, on WOT it was low 10's. so something was worng. Normally i would have 14+- on easy cruising and mid 11's on WOT.

With the maf disconnected it shows 12-13 on easy cruising and of course goes to max(22,3) if trying to build boost.

But this new maf hasn't even been driven yet and what are the chances i got a brand new maf with the same problem?

[quattrojan]

That should not happen if you have a bypass valve fitted. Check that too...

The bypass valve return hose goes into the 3" sillicone between the turbo and maf. I was gonna try just letting it go to free air and give a damn about the maf then increasing the fuel amount, but since the car doesnt run at all i'm back at start

[quattrojan]

Fuel supply maybe

Fuel preasure is at 4,5 bars when idling so that seems to be fine, but thanks to the advice

[JP]

If the maf is before the turbo on intake side it rips the fine wires then doesn't run properly. Happens due to the shockwaves. If you run the maf on the pressure side you won't get the problem as its a more table airmass. You need to make a strapped metal boost pipe contraption si you don't distort the plastic maf housing from over tightening the hoses. And open up the maf to seal the air pipe.

[prj]

If the maf is before the turbo on intake side it rips the fine wires then doesn't run properly. Happens due to the shockwaves. If you run the maf on the pressure side you won't get the problem as its a more table airmass. You need to make a strapped metal boost pipe contraption si you don't distort the plastic maf housing from over tightening the hoses. And open up the maf to seal the air pipe.

Except the fact that the MAF will read wrong, so you will need a (very thorough) remap anyway.
MAF on pressure side is just a crutch. Real solution is to fit a HFM5 and forget all about wires ripping.

[Astro]

Has anybody tried this?
It looks interesting.

http://www.abacoperformance.com/

[Costash]

HFM5Can you translate?

[prj]

Has anybody tried this?
It looks interesting.

http://www.abacoperformance.com/

For the price of those things you can buy a standalone, plus they will be useless without a remap.

HFM5Can you translate?

http://tinyurl.com/4de95fk