[Diy_efi] Re: Diy_efi Digest, Vol 13, Issue 1

Torbjörn Forsman torbjorn.forsman
Tue Mar 7 18:08:24 UTC 2006

There were some early cat-equipped cars that did not use closed-loop, 
instead there were two catalyzers and a air injection connected between 
them. The engine was tuned to operate with a slightly rich mixture 
(always lambda < 1), so it would produce much HC and CO but not much NOx 
emissions. The first catalyzer then effectively cracks the NOx, and the 
second one, which operates with lean mixture due to the air injection, 
will burn the HC and CO.
Of course, the two catalyzers often were combined to one unit with the 
air injection tube connected at the middle.
This system was abandoned when gas became expensive in the early 
eighties, as it gave bad fuel economy.

Best regards

Torbj?rn Forsman

Adam Wade wrote:
> --- Bill Washington <bill.washington at nec.com.au>
> wrote:
>>and thinking about it anyway, with a CAT fitted
>>running closed loop is mandatory.
> I believe that the first wave of cat-equipped cars had
> a few without an O2 sensor.  I know that there have
> been a number of motorcycles, largely Kawasakis, of
> recent vintage that have a high-flow cat and no O2
> sensor.  They clean up emissions *enough* to keep them
> within standard requirements, which have only just
> increased substantially in cleanliness.
> | Kawasaki Zephyr 615 (Daphne)       Kawasaki Zephyr 550 (Velma)|
> | "It was like an emergency ward after a great catastrophe; it  |
> |   didn't matter what race or class the victims belonged to.   |
> |  They were all given the same miracle drug, which was coffee. |
> |   The catastrophe in this case, of course, was that the sun   |
> |     had come up again."                    -Kurt Vonnegut     |
> | M/C Fuel Inj. Hndbk. @ Amazon.com -  http://tinyurl.com/6o3ze |
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