DFI revisited

[bcroe at juno.com]

If you know when to fire the plug, you ought to be able
to turn on the coil 4.4 ms early.  The engine rpm won't
change much in that interval.

Bruce Roe

On Thu, 25 Oct 2001 16:54:10 -0700 "Howard Chu" <hyc at highlandsun.com>
writes:
>> something.
> 
> And, having made that decision, I now realize I don't need to buy 
> any new
> sensors at all; the stock setup already has two CKP sensors and a 
> CID
> signal. I just need to tap off the CID and one of the CKP sensors to 
> keep
> track of which cylinder needs to fire next. The control logic will 
> be
> something like this: run a countdown timer set at a 5ms interval. If 
> the
> timer runs down before the next ignition pulse from the ECU, just 
> activate
> the current coil by echoing the ECU spark signal to the coil. If the 
> pulse
> comes before the counter runs down, then we have to start charging 
> the next
> coil while the current coil is operating.
> 
> So, the questions - has anyone done something like this before? It 
> looks
> like I need 3 inputs - CID, CKP, and SPARK and 6 +5V coil outputs 
> (These are
> LS1 "smart coils", remember). Any recommendations on how to do this 
> with the
> absolute minimum number of components? As another alternative - how 
> smart
> are these coils anyway? If I always tell them to dwell for two 
> cylinder's
> worth of time, will they operate correctly? (Someone please correct 
> these
> specs if I'm wrong: I believe the LS1 coils are 1Ohm resistance, 
> charge time
> of 4.4ms. I'm working with a maximum engine speed of 7500rpm, or 
> 2.667ms per cylinder. 

>   -- Howard
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