I've got this problem with the engine missing at higher rpms. Problem becomes worse as the boost increases. New plugs, BKR7E-11. Tried gapping them down to 20 and the problem is still there. Cap and rotor are good, not new, but in good shape with little to no carbon build up on the terminals. Car is tuned to 12:1 A/F ratio in boost and runs great under anything other then WOT. Problem is intermittant but 9 times out of 10, its noticeably missing up past 6k. Currently has Kragen wires on it, was going to get some NGK blues to begin with. Any other ideas? People whom have experienced this problem? Car is currently at 8psi. 10psi is pretty bad. Almost to the point where you notice no gains between 8 -> 10psi increase.

 

I would speculate it's the distributor or the battery/alternator. Put a volemeter on the battery and monitor voltage when you wind it up. If voltage sags that's the problem, if not then the dist is suspect. Or the dist/ECU circuit.

Of course, plug wires are also suspect. How about engine temps? Stable? Cooling system ok?

Any codes?

 

No codes at all. I don't suspect alt or battery. Both are in good shape. I will datalog some higher rpm voltage readings and check.

 

Good place to start - at least you will eliminate that and then you can move on to other things.

Battery voltage dropping will cause a motor to lay down @ WOT. The higher performance the motor, the more it can cause issues.

Is it leaning out? Did it run good, then develop the problem? Check fuel pressure too.

Speaking in general terms here - a boosted motor is fragile. If it's leaning down that's bad. Or detonation. So, be careful with it when testing.

Good luck with it!

 

I had this problem when my FPR line was split. So check it good. Then u can try to spray some CRC to your distributor cap / rotor / wires.

 

is it stock ignition? i doubt this is your problem but when logging keep an eye on tps. had a tps go bad one time and it had same issues.

 

Try gapping your plugs closer, like nearly no gap and report back. You might still be blowing out the spark. If not, I'd suspect dizzy. Both situations have happened to me (gap too big, and then dizzy went a year later)

 

I had this problem a long time ago it was actually the MSD ign box i was running, and I switched to an M&W Pro14 and walla no more issues

 

Stock ignition, yes.

I logged the battery voltage at WOT in second and third. Held solid at 13.6volts.

TPS also held solid at 4.55volts

FPR vac line is brand new, didn't see any signs of wear. It does have the BOV also tapped off that line as well.

I'll close the gap more and see what I get. If it does solve, should I suspect weak coil?

 

i had to gap mine down to.18 to clear up the breaking up

 

Just verified. Mine are at .026"

 

had similar problems, gapped down to .023 and it went away.

 

Shrinking the gap helped my break up under boost problems, but didn't solve them. I had a basically brand new set of Magnecor 8.5mm wires (1,000 miles on them). I tired everything. When I changed to a brand new set of NGK blues, all the issues were gone.

 

NGK ftw.

 

What map sensor are you running, how old is it and whats it look like reading wise ? Ive seen a bad map do this when all the obvious things like plug gap coil and distributor are confirmed good. Happend to me and several other people i know with a motorolla 2.5 bar

 

Map sensor is an Omnipower 3 bar. It seems to read nice and steady from datalogs. Its not too terribly old. I used it on my last setup I would say 4k miles.

 

i had break up problems with my ls also i gapped my plugs to 15 i also bought a msd external coil and ngk plug wires fixed all break up problems even at higher boost

 

Im going to regap the plugs tonight when I change the oil. NGK blues are on order. Prolly get them in a weeks time.

 

What about gapping with the MSD setup? Able to increase? Notice any power difference?

Thanks!

 

if gapping them smaller doesnt work and all the ignition components are in 100% working order i suggest it could be ONE of your injectors...i would have all cleaned dont think it cost too much...goodluck

 

If you run aftermarket coils off of stock ignitor it usuallycalls for tighter gaps from my experience anyhow. When I went from stock coil to msd coil I had to go from a .024 to a .020

if your running an ignition box however then you should be able to widen the gaps up a decent amount and get a better fuel burn without spark blowout. Currently running summit racig digital ignition box with mad blaster ss coil and the spark increased dramatically with the diital box and less strain on the ignitor which makes it run cooler so no failures

 

Gap to plugs to .018

What kind of power are you making?

 

You shouldn't need to gap your plugs that small. Replace your coil.

 

adding the msd coil and i also added a spc ingition i went from 382whp to 401whp with not touching anything then added 2-3psi more and made 419whp

 

Without changing the spark plug gaps? How much boost for 401 whp?