Collections vs. accumulations, was Re: How many collectors? - test-drb@ccmp.vtda.org

7 Aug 2001

...
  Douglas Quebbeman wrote:

 [stuff delete]

  So, prior to the fuel crisis and emission
controls, what was
 the motivating factor for the use of EFI?   
 Cost, weight and reparability.  Mechanical injection pumps have to
 be mechanically timed to the engine (either gear or belt driven off
 the cam), require their own oil supply and return lines, and have
 about 973 parts ranging in size from large to itty-bitty.  When the
 3D cam starts to wear (and it does) it effectively changes the map of
 the engine, and anytime you modify the engine in terms of 
 displacement or compression (or even futz with the exhaust too much)
 you have to re-profile that weird 3D cam -- something that requires
 taking the pump to bits and having a Really Good Time in a fairly
 specialized machine shop. 
But K-Jetronic (CIS) isn't timed at all- every cylinder port is
getting fuel at all times. The fuel distributor controls how much
by the area of the slots exposed int he control plunger as it
moves up and down in response the the motions of the airflow sensor.

But then again, as you and others have observed, CIS debuted later
than I thought... so I don't know as much as I think I do!

-dq