Thinking about making my own ignition cut rev limiter...diagram included

[sean350z]

I have a PFC and the fuel cut leaves my A/Fs at 13.5 at the rev limiter under high load. I don't want to spend 220-250 dollars on a Bee*r unit or 500+ on an MSD ignition seeing I don't really need the added spark capacity. So I want to make my own.

All I am going to use is a RPM switch ($40), SPDT relay ($5), and some wires and solder.

Is my wiring correct? Will this even work? I needs some thoughts and opinions seeing I don't know jack about electrical theory but just some small knowledge. Here's the diagram..

[lazierhobo]

it seems like a really good idea. fuel cuts like that are pretty horrible and i have seen many kids blow engines because of that.

why are you using the CAS signal line for your interrupt?

i would just use the power for the igniter or some other component in the actual spark system. im just not sure how the ecu will feel about you just killing the cas signal.

[drifting_changed_mylife]

thats pretty frikin smart! +1

[sean350z]

I have an S15 SR so I have no ignitor or single power source for the coil packs. Cutting the CAS signal will not cut fuel but will cut spark (I'm pretty sure).

[lazierhobo]

it will still cut fuel i think, cause doesn't the PFC use sequential injection? if there is no cas signal then it wont know when to deliver fuel.

if you wanted to be really baller, you could turn this into a soft cut rev limiter.
the way its setup on my haltech is i drop ignition to one cylinder at a time. just use multiple rpm triggers with the relay in series with the power signal to the coil packs.

or if you want to keep it simple, just rewire your coil packs so that there is a common power source

[sean350z]

Or you could just tie into the +12V supply for the coils which would be at the ecu relay.

[sean350z]

Originally Posted by lazierhobo

it will still cut fuel i think, cause doesn't the PFC use sequential injection? if there is no cas signal then it wont know when to deliver fuel.

if you wanted to be really baller, you could turn this into a soft cut rev limiter.
the way its setup on my haltech is i drop ignition to one cylinder at a time. just use multiple rpm triggers with the relay in series with the power signal to the coil packs.

or if you want to keep it simple, just rewire your coil packs so that there is a common power source

That would be nice. It would def require a circuit board which I don't have access to creating my own.

[lazierhobo]

you can buy all the stuff you need to make circuit boards at radio shack. and i really dont think you would need one. just 4 rpm switches and 4 relays.