Yamaha apex not firing on cylinders 3 and 4

[dtoybarn]

I have a Yamaha apex with turbo kit swapped into my Polaris RZR. Car dynos at about 375 HP with lower level tune running 110 race gas.

Running dyno jet ign and fuel modules with auto tune.

Was not revving past 6k rpm. Swapped coils and did some tests with fresh plugs as well. I am checking exhaust manifold temps and cylinders 3 and 4 are not firing.

I do have equal spark when tested individually
Have equal injector duty cycle and spray
Have equal compression across the board
Timing is correct as well with cylinders 1/4 at tdc at same time

What else in these motors ties cylinder 3/4 together? Is there a sensor somewhere that would put it in a limp mode?

 

[Srxspec]

Unplug the ignition module and see if the spark comes back. I'm guessing you have a faulty ignition module.

 

[dtoybarn]

Unplug the ignition module and see if the spark comes back. I'm guessing you have a faulty ignition module.

I have spark on all cylinders. Just not making any heat in those cylinders/not firing.

 

[Srxspec]

I have spark on all cylinders. Just not making any heat in those cylinders/not firing.

You have spark but it's not firing under load, again, take the ignition module off and try it. I'm gonna guess you'll find it's in your ignition module that is faulty. It has spark when there's no cylinder pressure, but when there's cylinder pressure it can't fire the fuel, which is why you have no heat.

 

[dtoybarn]

You have spark but it's not firing under load, again, take the ignition module off and try it. I'm gonna guess you'll find it's in your ignition module that is faulty. It has spark when there's no cylinder pressure, but when there's cylinder pressure it can't fire the fuel, which is why you have no heat.

Maybe I am misunderstanding but without my module won't I have no spark on all cylinders?

You have spark but it's not firing under load, again, take the ignition module off and try it. I'm gonna guess you'll find it's in your ignition module that is faulty. It has spark when there's no cylinder pressure, but when there's cylinder pressure it can't fire the fuel, which is why you have no heat.

 

[dtoybarn]

You have spark but it's not firing under load, again, take the ignition module off and try it. I'm gonna guess you'll find it's in your ignition module that is faulty. It has spark when there's no cylinder pressure, but when there's cylinder pressure it can't fire the fuel, which is why you have no heat.

What would you suggest I unplug? Will it have spark at all when unplugged?

 

[Srxspec]

Unplug it at the coils & crank trigger plug-in.