Detecting spark/ignition breakup at high rpm

[supraguru05]

I "think" I may be having some breakup at high rpm (5750)+ in my race car. Engine is essentially stock with 10 psi of boost. Ill be heading to a dyno this offseason to do some tuning with the SAFC2 I have (not installed yet) to try to get the air fuel ratios under control. My main question is how do I detect this breakup on the dyno and know its ignition and not fuel related? or is there a way? I heard some weird noises and some slight missing prior to rev limiter this last race at mid ohio. I havent changed the plugs yet (iridiums) but I do have good NGK wires and the awesome stock coil packs.

 

[Communistwookie]

I also get this "break up" around the same rpm on a stock 7mgte with NGK platinum gapped to .28, new tx08 wires, used coil packs, AFM tested good, running 10psi as well on 550cc/Lexus AFM. I have been doing some reading/ researching and still haven't been able to pin it down either. Figured my fuel pressure may just be off at high rpm as I don't have a adjustable fuel pressure regulator yet.

Good luck finding out what it is I'll be watching this thread

 

[Nougie]

I had a very similar issue as i thought mine was fuel/spark related. Turns out, it was a leaky/leaking BOV. Mostly "missed" in higher RPMs in 3rd!

 

[Communistwookie]

I had a very similar issue as i thought mine was fuel/spark related. Turns out, it was a leaky/leaking BOV. Mostly "missed" in higher RPMs in 3rd!

Thanks for sharing that, have had a suspicion that my hks knock off may have a hand in it, will have to replace it and see if that helps

Sent from my DROID RAZR HD using Tapatalk 2

 

[SeeUSmile]

If you got a oscilloscope around use it to monitor your ignition patterns. See if the A/F graph doesn't go haywire on the monitoring screen. Can't imagine spark blow out at just 10 psi unless your gaps are big.

 

[IJ.]

Spark blowout usually happens around Torque peak (5200ish) you can get around it somewhat if you have enough detonation overhead by cranking in a little more advance from high 4000's as this lowers the peak cylinder pressures.

Dropping the plug gap also helps as does a high energy ignition system.