Hi I have been reading up on Dfi systems. And the accel dfi 7 uses a dual sync distributor to run sequential injection....how is it possible to do that without a cam sensor ?

please educate me

 

In the absence of a cam signal, the DFI operates in a "random sequential" mode. It follows the firing order sequentially, based on a known crank signal pattern.

 

interesting!

It dosent sound very accurate..is there much advantage to doing that over normal batch fire ?

thanks

 

It's not recommended that you run this way intentionally. However, you still get the benefits of sequential: less fuel rail transients, individual cylinder fuel control...etc. If you are thinking about running sequential, definitely get the Dual Sync (or some other) sequential distributor.

 

wouldent a system like electromotive TEC3 be a better option since it have "real" sequential. With a high resolution ignition and a cam sensor. Their system looks very much like LS1 teknology. Not many people uses their system is their something about the accel that makes it the most desirable ?

thanks!

 

I don't know much about the tec3. However, I don't think older tec units could use stock cam/crank signals, you had to bolt on their crank trigger contraption. Don't think this has changed w/tec3, but I haven't used one yet either.

The DFI unit is software-configurable for many types of cam/crank/spout combinations. Either pick a predefined combination (Chevy HEI, Buick GN Coil Pack, Ford EDIS...etc), or select the cam/crank/spout trigger edges and signal levels that you want.

You misunderstand about the random sequential stuff. It is more like a failure mode such that when you are running "true" sequential, and you lose your cam signal, your motor doesn't quit. You can still drive home. The dual-sync distributor gives both crank and cam position signals to provide "true" sequential operation.

 

Must be one of em new fangled engineering terms. LOL

 

Technically the second pick-up in the dual pick-up distributer would be a cam sensor, it just does read the cam directly, but a part driven off the cam, like the newer s-series trucks, don't know what year they started with it, but I do know in '99 it has a cam sensor used this way.