Cam sync question

[RickWI]

On a sequential system I am wondering what is happening when I disconnect the cam sync connection on the distributor, fire up the car and drive around like normal. How can the engine fire if the sync is disconnected. Just wondering if somehow the computer assumes a postion for number one and considers that good enough? Basically the car seems to run just the same as before.

Wondering then if when the cam sync is connected if the computer just sees where number one is and after that never uses that signal until the next start cycle?

 

[RickWI]

TTT, anybody?

 

[Two Lane]

T T T

 

[Glen]

Not sure about aftermarket systems. Factory units have an extended cranking time and use resort to batch fire to control the injectors

 

[RickWI]

Thanks Glen, I don't think the FAST system would have the ability to default to batch, although I could easily be wrong.

 

[Craig Smith]

Without a cam sync, a FAST sequential system still runs sequentially. Injector timing can vary, though.

The system fires the injectors in order, ABCDEFGH, right from the start. Since the motor could be anywhere at the start of the cycle, though, the injector for cylinder 2 (for example) might open when cylinder 6 is firing. In most cases this doesn't really present much of a problem. As duty cycle increases the impact of this is lessened. Typically, the only time this creates noticeable problems is with really big injectors at low duty cycles.

The cam sync resets the cylinder counter inside the ECU. This means that injector A will fire immediately after the cam sync. If everything is wired properly this means that the injector will begin spraying on an open intake valve. More importantly, it means that the injector timing will be the same every time you start the car.

 

[RickWI]

Got it. Makes sense. Thanks for clearing that up for me.