TwinCharged RX7

iTrader: (14)

Hey everyone, can a lack of fuel cause misfiring?

It goes up to 18psi fine, then when we tried to go past that point during the tune, whenever we got above 7k rpms it would start misfiring.

I think it is a problem with my ignition system, but wanted to rule out fuel if I could.

I have the Aeromotive Tsunami fuel pump in tank, 1680cc secondaries, 720 primaries,

100% meth with 2 X 625ml/min nozzles.

Specs say: flows 360+ lbs/hr @ 12 volts/45 psi

Which i guess may be a bit lite, but with the meth displacing it during high boost i think i should be ok. Thoughts?

ChrisRX8PR

Assuming it is not too much fuel, your ignition, like your injection, has less available time to spark the higher the RPM's go. Your coils need a certain time in ms to charge before they release the spark(Dwell)...if at higher RPM there is less space for this than you need to maintain the park you now have up to 7k rpm...then your coils are providing a shorter/smaller spark up there and this could be causing the miss fire.

It might be time to upgrade your ignition. What do you currently have?

Chris

TwinCharged RX7

iTrader: (14)

I've got the Electromotive TEC GT system, which should be plenty.

Sometimes after a hard pull the tach will bounce to 0 and then back up when i let off, which the Electromotive tech thinks is a grounding problem, and he said if the secondary winding ground isn't right then when you let off after a load it causes a problem. So I plan to move the ground, he said this doesn't sound quite right for the mis-fire problem, but may be the cause.

He also said to check the crank trigger pulley to make sure its within spec in relation to the sensor, not sure how it could be off though, it was fine on the old engine, and i just transferred the pulley to the new one. He said as it spins faster and faster it may flex enough to become out of spec.

zinx

iTrader: (3)

Definitely something with the ignition. Tell tale sign when you see the tach bounce like that. Its loosing signal.

TwinCharged RX7

iTrader: (14)

Right now it is grounded by the coils and they said I should switch it over to a ground on the block. So that will be what I do first (rained all weekend so couldn't do it)

What do you guys think about the pump though, I had done quite a bit of research regarding what i needed for fuel during the build, but have now heard that it might not be adequate, is it too small, borderline, or sufficient for 500 - 550 whp?

zinx

iTrader: (3)

I think that pump is too small as well.

TwinCharged RX7

iTrader: (14)

well that sucks, i removed my walbro, could have just added another for like 60 bucks, instead i bought the bigger way more expensive tsunami, stupid move