My RX8 has been sputtering at idle for awhile now. It has new coils(bhr), plugs, air filter, clean ESS with reset maps, seafoamed, Catback, grouding kit. Fluids all flushed.
Had a compression test done a couple months ago, compression is good.
The rpms will dip just a tad when it sputters. And the sputter is pretty loud. With the hood up you can hear it from 10-15 feet away. Just sounds like a little popping sputtering noise.

I had a check engine light awhile ago, I wish I remembered the code but I lost the paper I wrote it on, it was like low circuit B or something, I think it was the air pump when I looked it up. But the code went away on its own.

I tried disconnecting the MAF sensor and letting it run on defaults and it still sputters so it's not that.

Any ideas here?
Thanks

edit: It sounds like the sputtering noise in this video if you skip to 14 seconds

 

Some possible causes:
- Front O2 sensor problem throwing off idle fuel trims
- Idle tune is just slightly subpar
- Coolant is leaking into the housing

Do you have any trouble with cold starts after it's been sitting a long time?

How is your 100% highway gas mileage?

 

Thanks for the reply!
I did have trouble with cold and hot starts until I put a new starter in, now it starts up right away with the bigger starter.
I haven't really paid attention to the mileage, I do a ton of city driving(washington D.C) mixed with highway so it's hard to calculate. I like to step on it real well pretty often too. From the times I've cruised around it seems pretty decent though.

If coolant was leaking into the housing wouldn't that put some white/blue exhaust fumes out and lower my compression though? I have checked my coolant a few times over the past 2-3 months(since the coolant sensor has failed on my car) and it's at the same level constantly.

 

A coolant leak will actually improve compression for a while, as it will clean the carbon before starting to corrode and sludge up everything.

Probably not a coolant leak from your additional information. It's just a possibility with a stumbling idle.

I'd get an OBD2 bluetooth/wifi adapter, pair it to your smart phone, and grab an OBD2 app. See what your fuel trims and AFRs do when it stumbles like that. You should be able to surf around the sensors and see exactly what's changing when it dips. We can go from there.

 

Oh interesting I didn't even think about that.
Okay great! I will get an OBDII wifi adapter and app and let you know what it says.
Thanks

 

Okay it's been longer than I expected due to some crazy life events, but I finally got torque pro and scanned everything. It pulled up codes P0336- Powertrain: Crankshaft position sensor A circuit range/performance
and also P2259-powertrain: secondary air injection system control B circuit low

So I'm guessing I need a new crank sensor, where is the sensor located, I've read it's located on rotor housing? Any more specifics, and what would cause the P2259, air solenoid?
Thanks!

PS: It also didn't start forever this morning, I have a brand new starter, and all I could hear was the starter whizzing away, the engine wouldn't turn over. I waited for a bit and randomly it started after that.