S4 B6 / 4.2 V8 BBK - Advice Please.

ShaunS3

ShaunS3

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Hi guys,

I've been knocking about on ASN for a few years now and have recently added a B6 S4 to my garage.

I have been scouring the net over the past few days and i cannot find a definitive guide or opinions on the PCV and SAI system fitted to the B6 S4.

I also run a 1.8 20vt S3 8L of which the PCV system was totally removed and replaced with an oil catch can.

From what i am reading on the net, either nobody has done it before or there are strong views against removing them.

Anyone able to offer some info here?

Thanks in advance.

:)
 
I don't own an S4 so not done this myself, but my understanding is that the problem lies if there is not enough pressure on the catch can side to pull pressure from the crankcase. Too much pressure in the crankcase will lead to blow seals, so my understanding although not very scientific would be;

Leaving turbo pressure as standard
Delete the PCV and SAI and run a catch can

Remap and uprate boost pressure
Delete PCV and vent to exhaust to pull through

Like I say, limited understanding but from what I see if you run just a catch can then the pressure in the crankcase would build if your boost is above standard, but on standard boost with a catch can, this should be fine and you'll notice a cleaner burn in the engine so smoother running and a better throttle response, or so some say?

Not a definitive answer but might confirm what you're thinking also
 
Cheers for the reply buddy.

The S4 B6 is 4.2 V8 and not turbocharged so turbo doesn't apply here.

Sent from my SM-G920F using Tapatalk
 
In hat case then vent to atmos shouldn't be an issue! Not sure what the fuss is about (on the internet) unless it's causing lumpy idling or something silly?
 
SAI pump is snnoyingly noisy and PCV hosing split...causing lump idle and random misfires due to evap leak.

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ShaunS3 said:
SAI pump is snnoyingly noisy and PCV hosing split...causing lump idle and random misfires due to evap leak.

Sent from my SM-G920F using Tapatalk
Click to expand...

Is this what you have now?

If so, then delete the system I would say. Having owned a few Audi's and VW's I've never seen a problem with PCV deletes. As we know these systems are designed mainly for emissions and "cleaner" burning engines, when in fact it gives a contaminated burn (with oil vapours).
So if you have a leak, I'd remove it, see no problem with that, even on the V engines this should be fine.

As for SAI, my knowledge is limited in that it's used for when the car is cold and requiring more air to aid in start, effectively a choke system. If you remove this then it might be worth fitting something like a K&N to aid a faster flow of air into the engine but other than that I've never heard of a problem, people were always removing the SAI's without hesitation.

I had a quick google but couldn't find concerns over removing these on an S4, what were the ones you've read?
 
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SAIP, secondary air injection pump, it's function is to draw air from the air filter box which is then pumped into a drilling in the head that enters the exhaust manifold. This will only run on a cold start for around 90 seconds, it's purpose is to add air post combustion, this helps the catalytic convertor burn off any extra fuel used for cold start and also helps heat the cat up much quicker, so essentially it's for emissions.
 
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QuattroCalum said:
SAIP, secondary air injection pump, it's function is to draw air from the air filter box which is then pumped into a drilling in the head that enters the exhaust manifold. This will only run on a cold start for around 90 seconds, it's purpose is to add air post combustion, this helps the catalytic convertor burn off any extra fuel used for cold start and also helps heat the cat up much quicker, so essentially it's for emissions.
Click to expand...
Trouble being although it runs on cold start only, i think the bearings have failed as they are constantly whining all the time despite getting a little quieter when warm.

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ShaunS3 said:
Trouble being although it runs on cold start only, i think the bearings have failed as they are constantly whining all the time despite getting a little quieter when warm.

Sent from my SM-G920F using Tapatalk
Click to expand...

I have a spare SAIP, if you can get part number and I can compare them, it will put EPC light on for incorrect flow detected.


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Thanks guys. Learnt some info here about possilby getting mine removed as I plan to go catless in the not too distant future.
 
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