After installing a K&N gen 2 intake on my RX-8 I couldn't help but notice that my idle is a little lower and rougher. I'm not talking much here (it went from 800 to around 700-750rpm) but as a result in the cabin the car idles a lot rougher. I haven't had my motor mounts replaced yet so I'm wondering if that'll go away afterwards, but I'm curious to see if this is normal for the idle to drop or if I may have a problem.

I've looked over the install and everything looks perfect. The vacuum hoses are all in place, the rubber tube that helps connect the intake to the throttle body is free of tears, and everything is tightened down nice and firmly.

The car is a '04 RX-8 with 32,000 miles on it. New battery, plugs and coils in the last 1000-2000 miles. Original spark plug wires (they were out of stock when I ordered the plugs and coils, haven't bothered ordering any new ones yet) and original motor mounts.

 

well recently my idle seems a bit rougher, and i have had an engine mount replaced a couple months ago [51k]. but then again i have noticed a bit of oil stains coming out of the intake filter. so im guessing im over filling the oil. [time for a catch can]

you can probably check if you have oil in your intake and clean your MAF

 

mine idles fine....but changing to Racing Beat soon....I just got tired of the loud intake noise.......

 

I love the sound of the intake and never had any problem with the idle. Car idles the same as it did with the factory intake. Hope you figure it out. Good luck.

 

When I installed the intake I noticed oil in my stock intake so I went ahead and cleaned my MAF sensor and disconnected the negative to reset the ECU as well. I'm wondering if that combination may have caused the idle to drop and maybe my idle was just a little on the high side as a result of the oil beforehand. Is the idle for an RX-8 normally around 700-750 RPM?

Last night I cleaned the MAF again (since it had a little oil on it from the K&N filter), reset the ECU again, and did the E-Shaft reset as well. I also checked all the hoses and they are all on nice and firm with no movement or play whatsoever so I don't think I have a vacuum leak. While I was in there I noticed that my positive battery cable was fully tightened down but was still moving around when I touched it so I got it nice and secure on there as well. That's the second time my positive cable has done that so I'm wondering why that's going on. I don't think it'll be a problem again this time though as I used a rubber mallet and lightly tapped on it to get it to go down on the terminal as far as it possibly could.

I'll take the car for a spin tonight or tomorrow on the way to work to see if it runs any differently.