My car has been bouncing at an idle for my a/f ratio from 10.4 k at start up to 15.4 at idle about 3 minutes into it.

That big of range is normally not good correct? What are corrective messures for this? Do I need to buy a SAFC or could a reflash of my ecu fix it? The car does have an intake and a exhast. My lack of knowledge towards tuning cars is.... if my exhaust is broken off would that effect it due to back pressure?

If it keeps running like this I can see damage to the engine , correct? Please help a newbie rx7 guy. Never had a car running this rough before!

 

These are numbers from a wideband gauge? Cold start mixture can be 10-11 AFR, and it should settle down to about 12-13 AFR when warm. The only way you could get 15.4 AFR at idle is if the air pump is diluting the mixture before the sensor. The engine will not idle with a true 15 AFR mixture.

What car is this anyway? If an S4 FC, you have the option of adjusting the variable resistor to tweak idle mixture. A rough idle can also just be a vacuum leak or TPS problem.

 

Its an S5 FC

So the exhaust would have nothing to do with it?

 

The only way exhaust can affect your numbers is if you have an exhaust leak before the sensor. You don't need backpressure. That's just a myth.

 

Good to know. I should prob bring the car to a professional to check it out. Once i get this boot off my foot i can actually get under the hood and do **** i need to do.