Ever since I put on the Power FC, the M2 intake resonates like crazy (I have the CF version). I'm guessing it has something to do with the fact that the emissions stuff is turned off because of the clipped wires or something?

 

The only resonance associated with engine control systems would be from the ACV dumping air back into the box. The stock air cleaner had a muffler for it. The M2 does not. When this air is dumped directly to the outside it makes a funny sound. Many years ago this was described as the "MOO FART" sound.

 

Hmm okay so why would it be dumping air back to the box now if it wasn't before? Shouldn't the air be going to the cat?

 

Very little air goes to the cat,some goes to the exhaust ports and a lot is dumped,depending on how good your airpump is.Above 3k rpm the airpump does not run.

 

Hmmm, okay. Does well to make my questions more specific then.
1. Does the PFC change the amount of air being dumped into the air box at idle?
2. Will my cat clog due to not having enough air going to it?
3. Is mooing at idle normal anyway or did I screw up something?

If it makes any difference I also installed a PFS intercooler at the same time that I put in the PFC.

 

1.not for my car,but maybe something else changed on your car.
2.no experience-always run with air injection system working.
3.I have silencer on mine--if you don't have factory airbox,you can get a silencer from a 2nd gen car. See your Red 90 TII.

 

This is quite normal and common, it was realy bad on mine when i had an HKS induction kit, much better when changed to Apexi induction and later when i fitted PFC the noise did change again.
I dont know if PFC changes signal to air control valve slightly.
It is possible to put a restrictor in the hose as some induction kits supplied these.ie a smaller hose inside the acv hose at airbox.
Unless someone has a better idea.

 

Remember that the PFC requires you to cut some wires or remove their load. One was on the ACV. Learn not to worry over stuff that has been in used for over 10 years without any problems.

 

For a long time my air pump was dumping air into the air intake, and I never really worried about it until I had to pass smog. In debugging, I found that the vacuum lines that are most likely to get damaged when removing or reinstalling the UIM will cause the ACV to dump air at idle. So you might want to check for vacuum line damage under the UIM.