JakeS2

Hi,
I've been looking at the diagrams and as I cannot figure it out for sure I have to ask, sorry.

So I have air pump "delete" done, the vacuum line to the valve is capped so is the pipe down to cats (which don't exist atm)

But , the airpump's tubes are there and the one that goes into airbox is there as well. Will this setup cause problems i.e. should I cap airpump's tube to airbox as well (yes, asking if the airbox hole needs to be capped.

Leon Speed

Yes.

JakeS2

Thanks! I'll do it during wknd. Well, the stuff was not done by me, I am just wondering the reason for strange emissions values...

Bart-Jan

The reason the airpump is there is because of the emissions values, so if you measure at the end of the exhaust, the values will be different. The airpump pumps fresh air into the exhaust right after the valves in the cylinderhead. The reason Porsche (and other manufacturers) designed it in this way was to circumvent the strong regulations...

I personally doubt if capping the airbox would change anything. Also if it would be needed.

JakeS2

Plus I don't know what it means as the pump itself is not driven (belt is off).


But the bigger stuff to change are now the distributor caps and -arms.

In addition I need to make some moving platform to my replacement engine which is due to arrival monday morning.

Leon Speed

Capping off the airbox prevents hot air getting into the box. It wouldn't be much, but still.

Talk about priorities!

TheoJ

Not entirely true. The airpump pumps fresh air in the last part (last 1/3) of the CAT, not directly behind the exhaust valves like some other brands do. This helps NOx values meet regulations.
regards
Theo

the flyin' scotsman

Actually both are true statements. The first S4s had the injection from the air pump into the cyl head which was later moved to the cats.

Air pump delete should block off the air filter housing after removing the pump, input and output hoses, diverter valve, metal line to cats.

Vilhuer

Non cat version always pumps into heads, even in GTS when M150 leaded fuel option was selected. Cat version pump into 2/3 of the cats in every car which had cats.

danglerb

I think the diverter valve runs off a thermal vacuum switch in the head so air is only pumped to the cats during warm up when the mixture is rich.