CIS-lambda frequency valve question

[drew at scirocco.cs.uoguelph.ca (Drew MacPherson)]

I was sure that I read in Watson's Tune&Modify book that WOT is "near"
100% duty cycle, but damned if I can't find it now when I've gone back to 
verify it.

Even if this is true, it could be overcome by installing a 
pressure-limiting orifice on the downstream side of the frequency valve 
(may require some playing around with sizes, I guess,) could it not?

Drew


On Fri, 24 Oct 2003, Dan Bubb wrote:

> WOT enrichment is only 65% IIRC, so going to a constant 12V would be way rich.
> For reference, cold running enrichment is 85% again, IIRC.
> Pretty sure I'm in the ballpark with the above numbers.
> 
>   ----- Original Message ----- 
>   From: Drew MacPherson 
>   To: scirocco-l@scirocco.org 
>   Sent: Friday, October 24, 2003 1:11 PM
>   Subject: CIS-lambda frequency valve question
> 
> 
> 
>   I've got a couple of questions about the frequency valve on the
>   K-jetronic-lambda implementation (what's on the JH engine in Sciroccos)
> 
>   The frequency valve is controlled by the k-jet control box based on input 
>   from the O2 (lambda) sensor which indicates rich or lean running.  By 
>   increasing the duty cycle on the valve the mixture is enriched, by 
>   decreasing the duty cycle the mixture is leaned out.  When the full 
>   throttle switch is closed (JH engine) the control module increases duty 
>   cycle on the vavle to "near" 100% (according to Watson's BOSCH fuel 
>   injection book.
> 
>   What I want to know is a) is the voltage to the frequency valve 12V or 5V, 
>   and b) will the valve operate reliably for short periods when a constant 
>   voltage (ie 12V or 5V) is applied, rather than a fluctuating voltage as 
>   applied by the K-Jet box.
> 
>   I'm looking for full throttle enrichment for my winter beater (87 Jetta,)  
>   which is running stock CIS (ie no lambda.) If I use a stock JH fuel
>   distributor, and wire the full throttle switch to supply 12V (or 5V) to
>   the frequency valve, then I should (in theory) get full throttle
>   enrichment, without having to worry about wriing in the K-jet control box
>   and O2 sensor (which I have less than zero desire to do.)
> 
>   Any (pertinent!) information would be appreciated... :)
> 
>   Drew
> 
>   -- 
>   /=============================================\
>   |  84 Wolfsburg Edition TurboDiesel Scirocco  |
>   |    http://scirocco.cs.uoguelph.ca/gtd       |
>   \=============================================/
> 
> 
>   _______________________________________________
>   Scirocco-l mailing list
>   Scirocco-l@scirocco.org
>   http://neubayern.net/mailman/listinfo/scirocco-l

-- 
/=============================================\
|  84 Wolfsburg Edition TurboDiesel Scirocco  |
|    http://scirocco.cs.uoguelph.ca/gtd       |
\=============================================/