My little race car I built.
engine stock bp4w, with injectors, Haltech elite ecu and E85 fuel. Non turbo atm.
The last track day each time I took it back out and sat on the dummy grid the engine was running on what seemed like 2 cylinders. Once on the track about a minute later it cleared itself for the start of the race. It did this several times during the day but only after sitting in the pits Turned off for about an hour.
A couple of guys with turbo Miatas said it might be the plugs as they get chewed up by the E85. I pulled the plugs they look to be fine.
when it cleared it was all of a sudden, I mean foot down on the gas on two cylinders then bang clear and runs fine for the whole 17 minute race.
Could coils do this? they are stock too.
i don’t think it would be vapor lock as it seemed to be either two cylinders on or four.

 

The 2 cylinder symptoms make the coils a definite suspect. Can you borrow another (known good) set to test?

 

Agreed.

 

Stock 97-00 coils are a known week point. Start there.

 

Sounds like coils like the others said. My coil failed at the Gap last year. It would be fine and then when it got hot it would randomly run on 2cyl.

 

Thanks Guys for the replies. I have read about the coils being weak/unreliable for a track car. I do have another set of used coils which I'll try. The problem with it being a track only car is the testing. I'll see what it does in the garage over the weekend.
Cheers boys & girls

 

This may or may not be the issue in your case, but I had a somewhat similar problem during a track day, and the culprit was the cam sensor.
The sensor acts weird just as it is about to die.
You might want to carry an extra just in case.

 

Thanks for the heads up, I'll keep that in mind. I always have a spare crank and cam sensor in the tool box.