Re: 747 crossfire conversion question.

[Shannen Durphey <shannen@grolen.com>]

With tbi, the goal is to keep enough fuel in the manifold.  It's not
like a sfi engine, where one injector delivers fuel for one cylinder. 
It's like a controlled carb intake.  You're providing a bunch of fuel
for each cylinder to draw from.  And no, based on the firing order, it
wouldn't work that way in crossfire.  Regular dual plane tbi feeds
every other cylinder, but the injector pulses are still not synched to
the cylinders.   
Yes the injectors fire with ignition pulses, but it's just a
heartbeat.  If you use a timing light shined at the injectors while
the engine is running, you can watch the spray pattern.  One of the
injectors will be in synch with your light.  If you snap the throttle
a few times, you'll see AE as the ecm supplies more pulses.  Then when
things settle down the same injector may or may not be in synch with
your light.
 
Shannen 


Kevin R wrote:
> 
> > They're not firing "off", because they were never synched to fire
> > "on".  They just shoot fuel.
> 
> According to the shop manual they fire with the ignition pulses, alternating
> at times and firing together at others. I just wanted to make sure that in
> alternating mode they weren't set a certain way based on timing cylinder
> draw i.e. firing the injector for the left side when igniting a plug on the
> right. Now that I opened my mouth I'll probably go and check and find out
> based on the firing order it Couldn't work this way :-)
> 
> Kevin R
> 
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