Ok, so this JUST started at the track this past weekend...The last 2 runs I started getting misfires in 3rd and 4th gear above ~5k rpms. The car is just stuttering and hesitating above 5k rpms under WOT, and it was a little worse today. My leading coil is BRAND new (< 1k miles on it), my wires are very new, and I just changed the plugs. I'm running 9's all the way around.

Dave @ KDR said that he'd be very surprised if my trailing coils were going bad, but at this point in time I think that's the only logical conclusion.

Any thoughts? I'd appreciate some input from the gurus. I noticed that this mainly happens after the car sits and the motor heat soaks. (I'm guessing this is due to increasing resistance in the coil/coils)...

I'm running a PFC computer, 850 primaries/1600 secondaries, HKS twin power ignition, aeromotive regulator, and RP fuel pump...I'm also running a coolingmist water injection kit with dual nozzles. Any other questions about my setup, just ask.

 

Really?? C'mon, I know SOMEONE has to have had this problem before...lol

 

what happens in the lower gears?
20 psi on 9 heat range plugs?
you made that power on a single RP/supra pump?
have you pulled the plugs to see if they're fouled?
also, are you running premix and how much?

 

check the fuel pressure.

 

I go through lower gears much quicker, so I don't really notice it...
We only did a couple of 20 psi pulls, actually. I typically run 17-18 psi of boost...The old plugs didn't look that bad when I pulled them. What heat range would you recommend?
I am running premix...typically 4-6 oz per tank.

 

This is my suggestion, make sure the map sensor is plugged in. Had a customer recently with your exact symptoms on a t78 fd, the vac line had popped off the 3 bar sensor and the car would simply run out of fuel right at 5k rpms.

 

I'm running an identical ignition setup with the same boost levels with no troubles.

I'd def listen to the other guys and check fuel px. You never answered my question about the pump and wiring. Also, when was the last time the fuel filter was changed?

 

That's an excellent suggestion, I'll definitely check it out! Although now I'm unfortunately out of town until this Friday, so it'll have to wait.

As for the fuel pump question, I am running the RP fuel pump from rx7.com, and my fuel filter has less than 5k miles on it.

 

i think im having similar issues... just curious why do you suggest checking fuel pressure? what relation does that have with misfiring?

i THINK im misifiring since my leading coil is going bad... when i throttle more than 50% it just back fires like crazy and i dont move... does this sound like misifiring? could i do any damage if i drive the car with misifiring issues?

ps i THINK i may smell a scent of fuel when i boost hard could this be related?

 

O LORD BENNY. That cant be good for business.

 

Having the same issue I think, let's have a look at fuel pressure and pump in the FSM.

 

FWIW, my problem was bad gas...go figure. Even paying for premium doesn't always get you the good stuff these days.