idle problems with AUX, VDI and emissions completely removed
 

i just bought a S5 NA for cheap because the owner cant figure out why it cant idle and stalls when the gas padel is let off.
OMP and emissions are completely removed except for the BAC. all unused vacuum nipples plugged

the AUX ports and VDI are completely removed (all the moving/actuating parts were taken out) my questions are can the car idle and not stall with out those parts? with good working senors can the stock ECU keep idle?

ive searched for about a day now and cant find answers.

As long as the holes were the linkage rods to the aux ports were are sealed then yes idling shouldn't be a problem. That said the problem may be the lack of the OMP. The S5 oil metering pump is electronic and if unplugged puts the computer in limp mode. Not sure how it normally runs in this mode but it pretty much renders it undrivable. Also you need the valve to the VDI in place and wired to it's high rpm or low rpm position once you get the car running as it changes the lenght of the runners in the intake manifold. Without the valve I don't know what you get but a unclear path for the intake.

The OMP is plugged to its harness and tied down near the strut tower.
Does anyone know if A wired open VDI be the same as a removed one? And does the VDI need to be in working order to have idle?

Probably rules out the OMP then. I misunderstood when you said "completely removed".
As to the VDI a wired open one would be different than a removed one if the valve is removed. If all that is removed is the actuator that moves the valve and the valve is still in place then there would be no difference. I know having it wired for high rpm operation makes no difference to the idle. I would think having the valve removed wouldn't either, bt can't say for sure. Maybe someone else will cime in. It would hurt power once runnig properly as you don't receive the benifit of either the short or long length intake runners without the valve. Maybe you have a vacuum leak somewhere due to all this aux,VDI valve removal.

having the valves removed should be the same as wiring them open.

but the previous owner created so many places for issues that you will be better off just buying an unmolested intake system and replace it back to factory spec.

removing all those parts just creates potential vacuum leaks and a slower car than a stock one. as i mentioned about a billion and a half times, unless the car is strictly for the track and only driven above 5k RPMs constantly then all of those parts should be left alone, they serve a purpose. only tool bags(tweakers and kids who think they know worlds more than the rest of us) ignore the advice and come here asking why their car drives like crap, you can understand that it is very aggravating when people don't listen.

you can open up the intake and exhaust, elimate the cat on the S5 and still have funtional intake valve system but the smog pump must remain to activate the 5/6th and VDI. this is about the best you can do for all around performance yet not lose much from your power band.

before putting a complete intake back on i would just clean up the VDI and the auxiliary port actuators/sleeves so that they are in good working order. this is sometimes why people ditch them, because they can stick and people take the "easy" way out which isn't so smart.

Not to hijack his thread but for my understanding when you say "having the valves removed should be the same as wiring them open." are you strictly speaking about the aux valves or the aux valves and VDI valve? I thought the VDI valve selected which set of runners short or long the intake used and opens the path for the pulses from the opposing rotors ports and having it removed would let the intake flow through both. I'm not at home or I would pull out my FSM. I can't quite get the picture in my head.

that is correct, and it would hurt idle quality to a small degree but without the VDI sleeve in place it would otherwise act full time in a similar way as a long runner system, VDI open.

i'd be more concerned about how to seal that VDI housing, the walls which you have to seal a block off plate against are very thin walled and a great place for a large vacuum leak to pop up.

without the VDI there would be no separation from primary to secondary runners, which i guess could cause more problems than i assume but i've never had anyone be so ignorant to remove the valve completely. most just wire it open.. in that event the secondary ports still receive no air until the secondary throttle plate has opened. without it air is going through primary and secondary port at all times which might cause more dramatic intake air turbulence with all the differing port timing conflicts.

After looking at my FSM and my spare UIM and removing the valve from it I believe I was mistaken in how it operates. It doesn't change the length of the runners at all. Only the path the pressure pulses from the rotor closing the intake port takes to the opposite rotor's intake port. Thus only creating the supercharging effect at high rpm. The FSM says because it is not needed at low rpms is why the valve is closed then. I'm guessing it must have some sort of negative effect as well, otherwise why have a valve at all and have it open all the time like those that wire it open.?

Yes, without the valve there is one big open cavity where the primary and secondary runners essentially become one. Not sure what goes on in there in this situation. I'd be inclined to agree that whatever block off plate they're using isn't sealing good causing a vacuum leak and/or this cavity created by the missing valve is causing a problem.