Fuel Cut Rev Limiter - Can It Do Damage

[turbo87]

Is there a problem with having boost in the chamber and no fuel? is it the same effect as leaning out or is it safe, as most aftermarket computers seem to use this function.

Just wondering, as my car can spend a bit of time bouncing on the rev limiter and my EMS only has a fuel cut function.

[Busky2k]

Apparently yes fuel cut can cause leaning out whilst banging the limiter. My theory is that as you're basically switching on and off the injectors whilst the engine is still breathing all the air in. So for example some piston intake cycles may not get the right amount of fuel it needs as the injector might only be active half way thru the intake cycle. Kinda hard to explain my theory. Ignition cut IMO is alot better.

Edited May 24, 2006 by Busky2k

[BOOSTD]

Ignition cut on turbo engines tends to cause fouled spark plugs....

[netrati]

Check out the MSD ignition thread. The DIS-4 has a soft-touch rev limiter. It randomly drops cylinders and picks them up on the next revolution, instead of dropping all cylinders at once. You can basically stand on the rev-limiter all day.

[carl h]

fuel cut revlimiters can cause detonation...best to stick with ignition cuts if possible, reason being there might be some fuel left over from a previous cycle and if it gets sucked in it can be ignited and cause a lean condition.

[PHATR32]

better fouled plugs than stuffed pistons.

does this MSD ignition plug into any ecu? e.g powerfc?

thanks

Steve

[turbo87]

Also interested in how this MSD works and what there worth

The DIS 4 is 4 channel, will that work on a skyline with 6 coils?

Edited May 25, 2006 by turbo87

[Sydneykid]

Turning the fuel totally off to a cylinder doesn’t not cause lean running in that cylinder. No fuel = no combustion, therefore there is no running for it to be lean. Remember we are talking maximum rpm here. In the unlikely event that there is any fuel left over from one cycle, it will be consumed in the nest cycle. One cycle of combustion of a miniscule amount of fuel will not damage anything.

cheers

Edited May 25, 2006 by Sydneykid

[Sydneykid]

Nah what I mean SK is if the fuel injector is switched off 3/4 the way through an intake cycle.. then... its lean for that cycle!

One cycle is not going to do anything.

Think about it, you snap off the throttle every gearchange.

The injector duty cycle goes to zero while you change gear

Until you get back on the throttle

What's the difference?

cheers

Edited May 25, 2006 by Sydneykid

[Busky2k]

Nah what I mean SK is if the fuel injector is switched off 3/4 the way through an intake cycle.. then... its lean for that cycle!