well as promised, heres my guide to removing the sai on the s3, first off i apologise for the lack of detailed pitures, i got half way through the job and realised i had forgot to take any, so ive done my best to highlight the important bits with things removed
also i would reccommend that you do the n249 bypass before doing this mod, makes sense really
things you will need:
blanking plate (http://www.forgemotorsport.co.uk/con...roduct=FMEGRBP)
coolant (i ended up completley draining my system)
10w 330 ohm resistors x2 (see http://cpc.farnell.com/welwyn/wh5-33...330ohmresistor)
5, 6 &8mm allen keys (must be ball ended)
soldering iron (for resistors)
an extra pair of hands always comes in handy
well it took me and my mate absolutley ages to do this, we hit a few problems such as a bolt being rounded off that secured the combi valave to the block and we didnt have a couple of necessary tools so had to improvise, but if all had gone well i would of said 2 - 3 hours
right here we go:
first off jack up the front of the car and get your axle stands under there, the higher up you can get the car, the easier you will find it to work under there! if you have the plastic undertray remove these (i took mine off a while ago and never refitted them)
get underneath and look to the drivers side inbetween the oil filter and auxillery belt and you will see the sai pump we are removing, there should be an electrical plug connected, pull this out and put it to one side for now.
now look down into the engine bay from above, remove the braided hose from your combi valave that goes to the n112 valve and now you can remove the metal plate that holds the n112 valve (put this to one side, we will come back to it later) now you can trace the two black hoses down to the pump, one will go from your airbox to the pump and the other will go from your combi valve, disconnect these from the pump (i found it easier to do from above but can be done from underneath too) if you are unsure how to do this disconnect the one from the combi valve first, just squeeze the two ribbed sides of the clip together and pull, it will take some force but it will go, once disconnected both hoses are clipped in place about half way along their length, find these clips and undo them then the pipes are free to be pulled out.
now get back under the car, at this point i would reccommend you wear some safety specs, in and around the pump is very ****ty and i got all manner of crap in my eyes but its up to you, there are 3 10mm nuts securing the pump to the bracket, two of them are easy, the third not so but it can be got at, just a bit fiddly, now your pump is loose but i bet you cant get it out, right?
look at the end of the pump where you disconnected the electrical plug, there should 3 plastic tabs spaced around the diameter of the pump, these are easy to undo, get these off and that end of the pump will come away from the main body, there is a plastic bush and spring in there so watch it dont catch you in the face! inside theres two wires connected up to the motor by spade connectors, pull these off.
now the pump still wont come out of the bracket at this point but you have just given yourself alot more room and manoveability! you should now be able to see two 8mm cap head bolts at the bottom of the bracket, jiggle the pump around to give the best access possible and get these undone, this is fiddly but keep at it, once they are cracked off they will come out by hand.
now you got two choices, depending on whether you got a mate to lend a hand or not, if you do then both get under the car and have your mate pull the bracket towards the oil filter (its a strong old bracket so dont be scared of giving it some welly) while you jiggle the pump around, theres a rubber hose on the aux belt side that gets in the way, you need to bend this as much as poss and slide the pump past it, trust me give it some force and you will get the pump out this way (this is how i done it) also if you choose to go this route you have the option of leaving the bracket in situ i.e you need not struggle to get the top bolt undone, just replace one of the bottom bolts to stop it vibrating
the second option is to undo the top bolt that secures the bracket, looking from above again, the bolt is inbetween where the thermostat is housed and the oil dipstick, a ball ended allen key or flexi drive is essential for this as the dipstick tube prevents you from getting in there square on (be careful not to round the head off) get this bolt undone and the whole thing will fall out the bottom, simples!
which ever way you decide to do it you will now have removed the pump, its bracket (unless you leave it in of course) and the two plastic pipes, now to be fair you have done the hard bits so have yourself a break!
all work now will be carried out from above, now if i were you i would drain the coolant system it saves getting coolant all over your bay and garage floor and is just easier imo but its up to you, whilst draining, remove your airbox and engine covers (if you havent already)
now you can see where your combi valave connects to the block and you can see the coolant pipe which is blocking access to the two bolts, so get that out the way and it is possible that you may have to disconnect the plastic coolant pipe from the block too (if you do take care there is a rubber 'o' ring seal in there dont damage it or lose it)
before fitting your blanking plate i cleaned up the surface of the block using some fine emery cloth just to ensure a nice clean seal, then fit your blanking plate, replace whatever coolant pipes you removed and refill/top up your coolant system (if you drained it remeber to bleed all the air out they system)
now going back to your n112 valve, nothing needs to be connected to this anymore and so can be removed from the plate completly, although if you cant be bothered no one will see it and it can be left there, makes no odds really, the hose that runs from your dv used to lead to the n112 and inlet manifold now only needs to go to the inlet manifold, all i done is to modify my existing tee piece that i put in when i done the n249 bypass
now all thats left to do is to fit your two resistors, one will go in the wiring for the sai pump (trace this wiring you should be able to pull this up into the bay save you trying to solder under the car) and the other will go in the wiring for the n112 valve, easy enough, snip the connectors off, strip the insulation back and solder the wires onto the resistors, cover in insulation tape and you're done!!
if plugged into vagcom you will get an improper flow fault from the pump, but if like mine yours was knackered in the first place then you would of got this fault before removing it, other than that you should have no codes, no warning lights etc
please note this is a guide, i cant take any responsibility for any damage done/caused by following this guide, this is exactly how i done it and i have had no problems at all.
please leave feedback if following this guide as to where you think others may benefit from additional information, thanks