Hesitation under acceleration S6 AAN

**UrS4boy** · 2 September 2007, 16:18

That's great you found the source of your missing/hesitation problems. Usually the issue is a plug, plug connector, POS or Coil. I have never heard of an air flow problem causing the problem. This probably because most people do NOT neck down the pipes/hoses to the MAF like your car's previous owner did.

But, after reviewing your excellent quality photos, I am perplexed: What is the fascination with cone filters? Yours looks like it has less gross surface area than the original panel filter. Your "heat shield" is a token effort and is about as good as applying sun-block SPF5 to the cone filter, i.e. very little benefit. Running a fresh air pipe to cone is a good idea. Too bad the factory did that with the OE flat panel air box which, for reasons not clear to me, people think is c**p. (It isn't).

Oh, yes, did you know the MAF is supposed to have screens both on the inlet and outlet to a) protect the hot wire and b) straighten out the flow to the hot wire?

Sorry but you posted the pictures and, once seen, I had to comment.

**AndyP** · 2 September 2007, 18:09

I agree, mine had a cone filter when I bought it and it was the first thing I ripped off when I got it home. The noise from the dump valve made me feel like a Barry Boy!!
The car felt so much smoother and quicker when I re-fitted the air box.

**smogthemog** · 2 September 2007, 18:50

This is the state of the bottom of the air box after the previous owner went to town on it

What a bleedin mess! - without filling in all the holes and fitting a new standard panel filter (which I ordered today) , I will not be able to see how it should run as standard.
I will endeavour to do this next weekend but as for now, the improvments I have made today to the power of the car - I am a happy man!

I have a few more plans up my sleeve to add to the air cooling system around the cone filter. I have thought about externally cladding the MAF with insulation material in an attempt to keep it cool and also adding further cool air pipes from the front of the vehicle. I have also toiled with the idea of extending the heat sheild, which at the moment is only there to stop heat radiation from damaging the plastics, to encase the turbo a little better in an attempt to keep the heat from the filter. Maybe a thin walled stainless tube around the whole filter being fed by the cool air pipe from the front of the car?

I dunno - it needs work..... I know this

**UrS4boy** · 2 September 2007, 19:12

I remember when I turned my Jetta 2L 16V air box into Swiss cheese and ran a K&N panel filter. Nice noises. - But not really efficient sucking warm air instead of cool/cold air.

There is a way with the C4 S4 to run an airduct (PVC plumbing pipe) from the OE airbox down to the oil cooler duct (right side "fog light" possition) and thereby get rid of "negative boost", i.e. pressure losses on the way to the MAF. The only down side to that mod, compared to the OE S4 duct from just below the top of the rad support, is you have to avoid going through puddles in case you scoop up water and "hydrolock" your engine (water is virtually incompressible) which causes it to break.

But, given that's an mostly avoidable risk, I would go down that route waaaay before I'd do a cone filter, even with a proper heat shield.

Google on Negative Boost to find out more.

Hesitation under acceleration S6 AAN

Hesitation under acceleration S6 AAN

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