Strange Intake Manifold Sound
 

While the car was on the dyno today, we have been trying to address some of the small problems that have surfaced. We've been able to figure out most but there is one that is baffling us.

There is a sound coming from the intake manifold when you give partial throttle, which sounds comparable to lifter tick in a typical piston motor (but obviously there are no lifters in a rotary).

Also under partial throttle the intake manifold actually expands and contracts, this is partial throttle blips revving to like 2000 if that.

While we are trying to fix this we are open to suggestion, anything will help right now :) thanks guys

Welcome to my world. I've been hearing this noise for a little over 2000 miles now, and have no idea what it could be. Good luck.

Scope your coils if tick increases with revs.

Could be a faulty SSV rattling with the pulses of the engine. Manually activate the SSV with a vacuum pump and see if it makes any difference. (I don't think the APV or VDI should cause problems because they are both rotary valves).

Maybe the one-way valve to the purge solenoid is rattling, once again, with the pulses of the engine? Disconnect and block the purge to see if it is this.

Loose fuel injector?

On the peripheral port engines I have heard of broken apex seals making this sound as they pass across the exhaust port (second-hand information this, maybe incorrect), which is of course impossible on the Renesis, but it could be a mechanical sound....

You will just have to go around isolating all the external components and listening for changes first. Good luck!

Mine makes this noise too. Been to Mazda with it twice. They say it's normal. I say bullshit.......going t another dealer, and a better mechanic hopefully.....