bobafc3s

So Im pretty sure i have an exhaust leak, I have an S4 Rx7 and if there is a leak big enough will it cause the 5th and 6th actuators to stutter when opening? Like I stepped on it over 3000rpms and I could feel the car dip and stutter then kick back with power. Will an exhaust leak cause this to happen?? I know that the S4 Fc's use exhaust back pressure to open the 5th and 6th ports. So somebody confirm me on this??

Thanks, and If there is should I get an aftermarket exhaust? Will those exhausts open the 5th and 6th ports correctly?

SureShot

Even a small exhaust leak on a rotary is very noisy, so you would clearly hear it at idle.
What you're describing sounds more like a mis-fire.
Things to check:
plugs
plug wires
fuel filter
secondary fuel injectors (since it happens at higher power)
engine-to-body grounds

FWIW, I am currently troubleshooting a high power mis-fire.
So far I've replaced the fuel filter, fuel pump, plugs, plug wires, & grounds.
Each item (especially the fuel filter) helped some, but it's still there.
My secondary injectors will get checked this weekend.

bobafc3s

well my exhaust has all restrictors taken off and its been ported. so its pretty loud so i can't really tell. but the fumes are pretty bad right now so im pretty sure its an exhaust leak. series 4 FC uses the backpressure to pull down the vacuums to open the 5th 6th actuators. so my question still stands will this happen with an exhaust leak?

kungfuroy

iTrader: (6)

Start your car on a very cold morning. the condesation will steam up and should escape were your leaks are at. thats how I found mine. Or you can just go ahead and replace all the gaskets if they havnt already. Less than a few hours of work.

SureShot

A loud S4 exhaust is a low backpressure exhaust, so the aux ports are probably not operating.
To confirm on the S4, you can put a dab of grease on the aux port actuator rod.
Then go for a ride and see if the grease gets pushed up the rod.