Fuel Injectors actuation patterns?

[BlackICE]

The GT has 2 identical fuel injectors for each cylinder, 16 injectors in total. Let's call them A and B injectors for a given cylinder. Does anyone know if one of the injectors is always fired first unless the fuel requirements require the second injector to fire in tandem? For example the A injector is always used until 300 HP is exceeded. then B is fired too. Or are the injectors firings rotated to even out the wear. e.g. If only one injector is needed use alternate using A and B until both are needed.

Any facts, or opinions welcomed on this topic. Even if your knowledge is from another vehicle.

 

[DoctorV8]

Great question. I can only offer insight on the 90-95 Corvette ZR-1, which is the only other car I know of that has 2 injectors/cyl. The LT5 32V motor that powered that car ran on a dual stage intake manifold that opened its 8 secondary injectors and 8 secondary intake ports above ~3500 rpm at WOT. Prolonged conservative driving on these cars often leads to coking/clogging of the secondary injectors from disuse.

 

[Fyr-FtrGT]

The GT has 2 identical fuel injectors for each cylinder, 16 injectors in total. Let's call them A and B injectors for a given cylinder. Does anyone know if one of the injectors is always fired first unless the fuel requirements require the second injector to fire in tandem? For example the A injector is always used until 300 HP is exceeded. then B is fired too. Or are the injectors firings rotated to even out the wear. e.g. If only one injector is needed use alternate using A and B until both are needed.

Any facts, or opinions welcomed on this topic. Even if your knowledge is from another vehicle.

Hi Clinton,

Per the Workshop Manual, "To provide smooth engine operation at idle, and at low engine load and RPM, one injector per cylinder is operating. As engine load and RPM increase, the PCM and FIIM also operate the second set of fuel injectors to provide adequate fuel to the engine".
Gary T.

 

[BlackICE]

Hi Clinton,

Per the Workshop Manual, "To provide smooth engine operation at idle, and at low engine load and RPM, one injector per cylinder is operating. As engine load and RPM increase, the PCM and FIIM also operate the second set of fuel injectors to provide adequate fuel to the engine".
Gary T.

This can be loosely true ieven if the injectors alternate. I guess I could use s stethoscope to find out.

 

[Shadowman]

I asked Rich aka The GT Guys this very question when they were here and as I recall Rich said that the secondary injectors (meaning the second set of 8) come into play around 3-3500 RPM. I also asked if they were tied to other variables such as load, throttle position, and boost and he said that they were solely activated based on RPM and that they do not alternate back and forth.

All the best

Shadowman

 

[BlackICE]

Thanks for the information Shadowman. I am giving some thought to how to make an add on board for the Racelogic traction control system so that it will work on the GT with 16 injectors. If I can be sure than the secondary injectors only fire at the same time as the primary, then the circuitry will be simpler.

As they say KISS (keep is simple stupid).

I am not a great fan of most traction control system. The one on my BMW 750 bugs me how it drops power when I am powering out of a corner. It upsets the balance of the car in an un-natural way. However from many of comments on this board and from conversations with people with modified engines, you just cannot get the power to the ground in the lower gears. I think the Racelogic device can help here, but it doesn't work with more than 8 injectors. Just think what a consistent launch would do with a 800 hp GT in the TX mile. I think you would get kicked out on the 1st run if you didn't have a roll cage.

 

[californiacuda]

The Racelogic can also be purchased to cut spark instead of injector. I own one that I originally wanted to put in the Gt, but because of the dual injectors I can't use it and I am planning on putting it on another car. If you can figure out how to cut both injectors, I would be very interested.

 

[BlackICE]

The Racelogic can also be purchased to cut spark instead of injector. I own one that I originally wanted to put in the Gt, but because of the dual injectors I can't use it and I am planning on putting it on another car. If you can figure out how to cut both injectors, I would be very interested.

The cut spark won't work either because of coils on each plug. The racelogic unit only works with 2 coils. Also I don't like the spark cut method as much as the gas cut. It hurts the mileage and environment.

I emailed racelogic on getting some specs on the electronics on the unit. Some tests on the GT will need to be done to verify when the injectors fire, but I think it is doable and the wiring doesn't look as ugly as I 1st thought. Although it will require cutting more than 16 wires on the harness to spice into.

I would caution those thinking about it, failure modes may be ugly if the racelogic or add on board don't cut enough fuel to stop ignition. I can see a lean condition and BOOM! As devices can fail even if designed correctly and adding more parts in the chain of things that have to work increases the probability of failures.