High-RPM raspyness/misfire with new ignition system
 

Hi Everyone,

I've had my S2 for almost a month now, and have felt that something was off with it at high engine speeds. It sounds very raspy & fuzzy, and occasionally it feels like there is a slight hesitation or misfire over 7000 RPM. I've replaced the plugs, wires, and coils with new NGK & BHR parts (one at a time to avoid mixing up wires), and replaced the air filter with OEM but that's about as far as I've gotten.

There is a track-day that I'm signed up for in a week, so I would really like to get this sorted and make sure that she is in good health. This weekend I plan on:
- Checking, cleaning, and running more ground wires (battery, Ign coil tray, Intake manifold, chassis on both sides near strut tower brace)
- Cleaning the MAF
- Checking all the plug wire connections, adding dielectric grease

To this end, is there some way to tell what wiring harness plugs refer to L1, L2, R1 & R2 coils, just in case a previous owner mixed two up or something?
Is there anything else that I'm overlooking that could cause a high RPM misfire?

Thank you!

Oh, to add to this, there is no CEL, blinking, solid or otherwise, and no stored or pending codes (at least that I could read through an OBD bluetooth tool and Torque on my phone). Below 6000 RPM, the car is as smooth as can be, no stumbling at idle, starts up very quickly and pulls well.

Ok, a little searching later, and I'm adding cleaning the ESS to the list too. Does the 20 brake pedal stomp reset thing work for S2's as well as S1's?
- Check the catalyst.
- Are the S2 fuel pumps as prone to issues as the S1s?

The method to clear the ESS profile on the S2 is different:
https://www.rx8club.com/series-i-tro...memory-169443/

The firing order for the S2 should be the same as the S1. The OE wiring harness for the coils should be sized closely to reach each coil (i.e. it should be obvious to see which connectors connect to which coil).
From the front of the car moving back the order should be LF, TF, LR, TR.
https://www.rx8club.com/series-i-tro...-order-208027/
http://www.racingbeat.com/images/items/11516.1.jpg

Make sure you got the plugs themselves in the correct locations. I've heard that the engine will run but not very well if you mix them up.

Other things that are load/RPM dependent: intake valves. Make sure your VDI and SSV solenoids are working properly and that you don't have a vacuum leak around the accumulator the solenoids mount to.

I'll definitely be double-checking the plug wire routing and that everything is still clipped in place properly. I *think* that is the order that was there when I did them, but don't remember completely.

I hadn't been thinking about the intake system valves - I'll see if things seem to move smoothly, and as long as the actuators aren't junked up, wouldn't a vacuum leak show up in the idle speed and an electrical fault be a check engine code?

S2 fuel pumps are better. If you have a fuel pump issue, it will likely reflect as a hot start problem after a hard drive.

Well, I don't know precisely what fixed it, but I checked the cat and it looked perfect (phew!), all the plugs were in the correct place and all the wires felt like they were on, but I pulled them all off and added dielectric grease on both the plug and coil side, just in case, the MAF resistors and thermistor looked clean but they got blasted with MAF cleaner anyway, the ESS looked clean as well but it also got scrubbed, and finally I pulled the battery connections off to clean them and add dielectric grease as well (and left them off for ~15 min, and held the brake pedal down to relearn the ESS and reset the NVRAM). Now, she's smooth as can be, and really pulls above 7k RPM. Such a relief, and so addictive!

I didn't check the intake system valves since I was running out of time, but with this result and the lack of ECU codes, I think that they are probably OK for now.

Thanks for all your help!