Integrated MAF pipe

[prj]

Yea it depends on the tuner I suppose. Mine certainly runs better with the pressure maf.

No one can bend the laws of physics. But there is pretty much one tuner besides Bosch who can actually datalog these ECU's and see what is going on as opposed to going blind...

When you only have VAG-COM (utterly useless on these ECU's), then of course everything seems fine and dandy.

Not to mention that your statement is just wrong. It does not "run better" because someone put the MAF on the pressure side, it "runs better" because someone poked around in the ECU.

But enough on the subject - experience has showed me that it does not matter what you say, there are 10 people for who "this feels better" and "that feels better", and no one who has numbers to back up anything they say on here.
I've mapped a dozen cars with the MAF on the pressure side, and I've seen pretty much exactly what happens - the biggest issue, if the wire remains in place, is signal degradation over time.

[tomwood_uk]

Ok well according to you it dosent run better. I'm happier with it. Is that better?

[S2central.net]

The MAF is maxed at 400-ish hp anyway, so that car is just mapped alpha-n if it is running a MAF.
All stoneage methods though. I map all higher powered cars without a MAF these days.

There is a reason I say what I say, might have something to do with the triple digit number of different 2.2T cars mapped. You are free to disregard it however.
As the saying goes - smart people learn from other's mistakes.

Yeah - no argument there... apparently the MAF is used on that one for idle & part throttle only but it still amazes me the MAF survives the physical force of air moving in & out !

[nesshead6]

I'm trying to see the benefits of doing this, care to explain?

Anybody??

[andy10v]

Anybody??

Packaging, space, with tubular exhaust manifolds and large turbos there is not a huge amount of room left for a MAF and airbox.

I think there were old posts on here that people with problems with the MAF wire getting damaged had less issues with it on the pressure side surprisingly.

[4WheelDrifter]

Packaging, space, with tubular exhaust manifolds and large turbos there is not a huge amount of room left for a MAF and airbox.

I think there were old posts on here that people with problems with the MAF wire getting damaged had less issues with it on the pressure side surprisingly.

Also when people started using Garrett BB turbos they had trouble with compressor surge at idle, and the MAF didn't cope with the reverse flow very well, and the engine would often stall when rpm dropped. I am pretty sure that the HF MAFs don't have this problem, but obviously Dmitri knows more about that.

[S2central.net]

The HotFilm MAFs don't suffer from wires ripping off, but I recently learnt that they do suffer from potentially serious drift (inaccuracy) issues over use which give rise to lean running - you cannot run them without a full time WBO2 display to verify that mixtures are safe. There is a lot to be said for the simplicity and flexibility of speed-density systems on vehicles that are targeting an excess of ~400bhp.

[A80Avant]

The MAF is maxed at 400-ish hp anyway, so that car is just mapped alpha-n if it is running a MAF.
All stoneage methods though. I map all higher powered cars without a MAF these days.

There is a reason I say what I say, might have something to do with the triple digit number of different 2.2T cars mapped. You are free to disregard it however.
As the saying goes - smart people learn from other's mistakes.

I know it's a different thread completely but what ever happened to the rs4 maf hoo ha? Now you are mapping without a maf altogether.? What ever happened to the long speeches of the maf being so important to monitor as measure the incoming air so as the mixture is always perfect etc etc etc?

Have you found a way around that now?

[S2central.net]

Lets not start another fricking argument... all systems have pros, cons and limitations !

[A80Avant]

Lets not start another fricking argument... all systems have pros, cons and limitations !

It's not meant to be an argument in anyway. I just find it interesting that a solution may have been found in that good old motronic unit that is just as good as 1000+ euros of aftermarket ecus

[andy10v]

With the MAF on the pressure side will the ECU still see a boost leak?

[S2central.net]

Thats an interesting point... MAF on pressure side will only measure air that is drawn into the inlet manifold... it would self correct for any air leaks between compressor output and the MAF (such as pipes and/or intercooler)... but its only really relevant up to ~400bhp

[S2central.net]

As an afterthought... the best way to increase life expectancy of a MAF on the vacuum side (before compressor inlet) is to run it with a DV (or two) that vent to atmosphere - this will prevent the reverse pressure blowing back on the hot wire when you lift off for gear change etc... but like many people I think it sounds totally crap and is a waste of all the effort gone to inhaling that air in the first place... the factory recirculating DV does a nice job of directing that air back into the compressor to minimise turbo stall - but at risk of hotwire damage.

So there are some choices when you get much above 400bhp -

1. Do nothing... keep stock MAF on vacuum side and carry a spare at all time as the hotwire is prone to failure
2. Move stock MAF to pressure side and have Motronic remapped accordingly (with alternative methods at high load)
3. Go for HFM on vacuum side and have Motronic remapped accordingly (must have WBO2 for insurance against sensor drift)
4. Delete the MAF altogether and have Motronic remapped for speed-density methods
5. Go aftermarket ECU with speed-density methods

[andy10v]

Thats an interesting point... MAF on pressure side will only measure air that is drawn into the inlet manifold... it would self correct for any air leaks between compressor output and the MAF (such as pipes and/or intercooler)... but its only really relevant up to ~400bhp

Would that not cause the turbo to overspin with a slight boost leak prior to the MAF?

I assume a major boost leak where the target boost was not reached with the n75 duty cycle would result in the ecu throwing a hissy fit?

[S2central.net]

Well as I understand it.... in that case... N75 will indeed be cycled harder to try and hit target boost, but only by an amount permitted by 'adaptation limits' - after which the ECU would throw a code along lines of boost pressure not obtained. The end result will be low boost pressure and a fault code stored, but the MAF will have measured the correct amount of air entering the engine (as long as the long is upstream of the MAF).