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important
I also found this in another section. Sorry I'd saved the text from a thread a while ago so I can't credit it to anyone apart from "Joel Reiser"
QUESTION
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This is a follow-up question to "Boxster 3.4L Upgrade" In this detailed reply from Joel Reiser he mentioned a Resonance Flap and a part from the Home Depot Plumbing Dept. I have a 1 week old 1997 Boxster 3.4L Conversion with a 1999 996 3.4L engine. This engine has a Vacuum driven Resonance Flap.
Resonance Flap:
Joel stated "You also need a 996 ECU, or a Boxster S one, to operate the resonance flap (like VarioRam only not as involved). Without this it will make no power whatsoever, less than before. That feature also requires running a pair of wires from the engine to the ECU"
Q: What pins on the ECU need wires to be added to them?
Q2: Where do these wires go? 12v Vacuum Valve? If so Part Number?
Home Depot Part:
Joel Stated "An air cleaner hose has to be adapted, we've used a Home Depot hose from the plumbing department." MAF to Throttle Body
Q: Can Joel provide a better description of the part? What is it used for in the plumbing Dept, etc. How much it cost approx?
This info might help me locate the part for my project.
ANSWER ---------------------
I can't tell how far along your project is. If it's been up & running for a week, and making more power than it did before, you should be OK. But if you mean the engine is in, and now there are things to hook up before testing, then read on.
After all your hoses and wires are connected and all fluids topped off, idle the car and rev it by hand gently. With the car sitting at idle, you should see the resonance flap switch over at 3120 rpm and switch back at 5120 rpm if the throttle is open by at least 30% momentarily (!) as you rev it by hand. That vacuum device you mentioned will pull its lever to operate the flap when the ECU tells it to. So, yes it is vaccum, but it is also electrical. If it does not operate, you'll be down about 50 or 100 hp. I don't know why it makes such a big difference, maybe the ECU goes into limp mode awaiting a tow truck and a repair. If you don't connect the resonance control line to the right ECU, the entire project is a waste of time.
If you used a 996 or Boxster S intake system you already have the resonance flap and its actuator (solenoid). If you used the Boxster 2.5/2.7 intake system, you have to take it all off and start over. That intake does not have the second cross plenum, nor the resonance flap hardware or tuned chambers. When you finish flipping the 996 intake system around backwards, to get it to fit in the engine bay, the air intake duct from the airbox does not reach the inlet of the motor. Now we're ready to go to Home Depot. Just measure how far you have to go, and your diameter. Go in the plumbing department and look at the big black hoses, there is only one that is even close, and it is almost perfect. I did not record the SKU number the few times we did this, sorry. They can change the SKU number anyway, any day of the week, retail store rules are different from car parts.
The 996 3.4 liter engine vacuum unit for the resonance flap is part #993.110.462.02. Same as is used on the Boxster S, and on the 993 obviously.
You need to run a white wire from its pin 2, to pin 59 on the ECU. You will likely find your wiring harness connector has an empty hole there instead of a pin. So you need a few new pins. It's an Audi part but I don't have the part number.
Yes 12v is a good guess, since the other side of the connection is to the nearest handy source of switched & fused power, red/black on the VarioCam adjusters. Or you can run that back to the ECU as a completed pair, like I do, using pin 54 just because its compatible and its adjacent. Use something sharp to poke a hole in the rubber grommet that passes through the firewall, then plug the hole with your two wires. Use cloth electrical tape to tie your pair in to the harness, and hand yourself $450 for not having to change out the wiring harness.
Joel Reiser /
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