ELEVENS

Or did you leave the air horn and only remove the flap (like others have done).

silverRS4

2) the function of the electric switch,3)the function of the vacuum side of the switch and 4)the horn's ability to open/close the flap. The operational check asks the whole system to duplicate exactly what it does when the car is going down the road. Its ignition on, engine off - not everything off and some yahoo sucking on the vacuum line. The ECU signal is the same whether the car is moving or not. Its perfectly suited for checking the system when the system is working and even better suited if the flap is stuck, i.e., if the op check can't open the flap when your car is sitting still, its highly likely the signal won't open it when the car is going down the highway.

ski35off

I am, however, still horny as ever

ski35off

...to open the flap when expected during real driving situations.

two2

nice writeup.

i still have my flaps., is it really worth this trouble?

gains, if any? what about sound no difference? just curious as im debating to do this.

ELEVENS

LOL - Bob's pretty quiet, we must have caught him snoozing.

silverRS4

In modern fuel injected systems, most problems arise from faulty sensors or actuators. I was under the impression that the flap would allegedly get stuck closed since its a plastic flap in a plastic housing. How would you know its getting stuck? There's no feedback to the ECU to identify its position (so you're basically in the dark until you can generate a signal from the ECU and watch the flap with your eyes). The de-flap originated when few knew the difference between the intake manifold flaps and the power flap in the airbox. There were vacuum hose problems which led to intake flaps not working properly, but the ECU has feedback on their position so if there's a problem, you will know it. The fact that there is no feedback on the air box flap says either the engineers forgot something, or the airbox flap is not critical to engine operation or emissions.

Bob W.

I didn't win the car in some damn contest, ya know.

Bob W.

he's the one who inspired me to do it, albeit with a different approach. I think he had completely disassembled and reassembled the entire car in his first week of ownership, and now he just does it for fun when he has a couple of hours to kill. Blindfolded.

ski35off

I was not remembering the "history of de-flapping" correctly.

The way it's supposed to work was described <a href="https://forums.audiworld.com/rs4b7/msgs/52116.phtml">here</a>:

"To ensure a sufficient supply of air to the engine at high RPM, the power flap in the air filter is opened at engine speeds higher than 5000 RPM and at road speeds higher than 200 kph. The power flap is opened and closed by a vacuum actuator which is map-controlled by the ECM via the Intake Air Switch-Over Valve N335."

At one point I believe Bob W. did some MAF logging tests with and without the flap (or was it with and without the horn?) and it was determined that there was more air flow in this arrangement, even at &gt;5000 RPM.

At a minimum, the de-flapping makes the car sound cooler at lower RPMs

:-)