I read somewhere that a simple 'Happy Flappy' test can be done. You attach a piece of tape to the top of the shaft that the flappy rotates on (under the black rubber cap in the center of the intake plenum)so that the tape acts like a flag. Supposedly on start up, the flappy will make a brief 1/4 counter-clockwise turn - which means the tape flag will turn - before returning to normal position.

Thing is, I tried it with my '91 GT and my '90 S4 and neither one made the turn. I have a thing against excessively revving an unloaded engine, so I don't want to rev up to the 4k or so that would be required to turn the flappy.

Is there a simple Happy Flappy test that I can do, or are both of my flappy's sad?

 

get over your "thing". 4k ain't gonna hurt it. that IS the simple test...

 

According to the LH Test Plan, "Start engine: valve opens and closes on starting. Accelerate abruptly to wide open throttle after engine is running: valve opens and closes. (Conditions: speed greater than 3500 rpm and at least 1/3 engine load.)" Use the MightyVac to see if the flappy is stuck or or if the actuator leaks vacuum. There should be enough of the shaft sticking up to grab with a pair of pliers. Turn to see if it is stuck. (Mine was.) This eliminates the possibility of stuck flappy or faulty actuator. If these are OK, you could apply power to the solenoid valve that supplies the vacuum to the flappy actuator. (There must be vacuum in supply tank for this test.) Work back from there. Check to see if solenoid valve is receiving voltage. Bridge terminal 17 and terminal 21 on LH control unit plug with help of an auxiliary lead. Apply ground on terminal 34 of control unit plug with another auxiliary lead. Resonant flap should open. If flap doesn't open: Connect terminal 17 and terminal 21 on LH control unit plug. Disconnect plug on solenoid valve. Connect voltmeter on plug receptacle (pin 2) and ground. Voltmeter should display battery voltage. No display?: Check power supply to solenoid valve via relay XXV to wiring diagram and test power flow from LH control unit terminal 34 to solenoid valve plug connection (pin 1). These are the procedures for MY '87 S4. Good luck!

 

Thanks for the responses, gents.

The shafts turn with pliers, so that is not a problem.

I will try again today, although I am not going to have enough time this weekend to go through the entire procedure that Steve outlined. I have to install my new RMB!

 

<img border="0" title="" alt="[Wink]" src="wink.gif" /> haha... First things first! <img border="0" alt="[burnout]" title="" src="graemlins/burnout.gif" />