Hi all,
It's been awhile and even though I've moved to racing/riding motorcycles but I still love my S. Unfortunately it (S2000 with SOS Stage 2) seems to be under the weather.

It acts like it is running on 3 cylinders, but it's intermittent.

Replaced:
1) Spark plugs
2) Primary O2 sensor
3) Coil packs

Added:
1) Injector cleaner
2) New gas

All of the above have improved how it runs, but it still is running a little low on power.

I was considering replacing the Map sensor next (still stock) and then looking into potential injector issues.

I welcome tips/suggestions. Is there something else I should look into?

 

What injectors are you using? The id injectors pnp harnesses are notorious for failing and causing a misfire

 

X2. I would look here first.

What engine management are you running? Log and you should be able to see a bit of what is going on.

 

Quick and dirty way to see if it is an injector/harness problem is to have the car running. Remove injector plug #1. The engine should run a little rough. Plug back in the harness and the engine runs normal again. Repeat step for injector 2-4. If it is a injector or harness issue, you'll know because removing the injector plug will not affect how the engine is running.

Was on 3 cylinders before due to a injector harness issue and the car was idling rough and noticeably sluggish. Fix the injector pin and everything was back to normal.

 

Thanks for the replies/thoughts. AEM is the engine management system and RC Engineering Injectors.

I did the unplug/replug process for all 4 injectors and it ran a little rougher than the usual rough for all 4 when unplugged.

I'll look into how I can pull a log from the AEM.

 

If it was running on 3 cylinders you'd sound like a Subaru and have no power. In your case sounds intermittent, hmm.

 

Just do a compression test to check:

http://www.autolifers.com/how-to-diy-compression-test/