Mixture question

[type53 at gmail.com (Drew Mac)]

On 5/23/06, Dan Bubb <jdbubb@verizon.net> wrote:
>
> It's long been my understanding that adjusting the mixture on CIS
> mostly affects idle and has less and less of an effect as the fuel
> metering plate moves higher.



I've often wondered the same thing, does changing what is essentially the
rest postion of the control plunger have any effect on fuel delivery above
idle?  I have experienced improvements in driveability (on the same engine
as what Cathy's using, as it happens) through adjustments to idle mixture
though, but can't explain why...?


At least that's what my engineering sense tells me.
> So.....that means you'll have virtually no effect on cruising or WOT
> mixture if you're idle mixture is in the range where the engine will
> actually idle.
> Anyway, I'd set the idle a tad rich from stoichiometric. Most engines
> like to idle a little on the rich side.
> But, I am curious if adjusting the idle has any effect on cruise or
> WOT AFRs?????



Me too, but Cathy wouldn't tell what the numbers were to start at WOT, I
think she was too busy looking at the road... :P

My thoughts in this area are to dynamically adjust control pressure (without
installing CIS-E!) based on load.  Many CIS cars had vacuum input to the
control pressure regulator, I'm wondering if "upgrading" to one of these
CPRs would help, now that Cathy has WBO2 and a stable (i.e. non-assrunning)
environment it's easier to track the effect of these changes.

Essentially though she's running a stock 1.8 (non k-lambda) distributor now,
so the only thing that will reveal if fuelling is adequate for the
application is the AFR reading and the (butt) dyno...   Shimming the fuel
distributor to decrease control pressure is an option, but last time I
checked the shim kit was NLA from the dealer.

Now we have to wait for Cathy to do more fiddling around with it!

Drew

Dan
> who would have responded long ago if I'd have noticed your original
> post and WB-O2 content ;^)
>
>
> From: "Brian McGarvey" <bmcgarvey@gmail.com>
> Sent: Monday, May 22, 2006 9:43 PM
> Subject: Re: Mixture question
>
>
> Because I didnt know all the facts.. You said 8v @ 10.1:1 compression I
> immedialty assumed non-stock or 2.0l aba. I can confirm the small 8v
> (1.7EN) CIS-Lambda will run an 11:1
> 2.0L aba -- although not well the JH CIS fuel dizzy and armature works
> much
> better doesnt knock at WOT... or hot days.
>
> But the basic thought was VW in the 70's and 80's was worried about long
> lasting cars and pretty good fuel mileage. so running lean at load would
> be
> seemingly a bad idea. I was assuming you were not getting enough fuel at
> load...
>
> and since your running CIS ( no lambda correction ) and knock box ( ign
> retard on knock) you are running a non-factory option setup. IIRC...
>
> Rich at idle + stoich else is ok. afaik...
>
> see you in a couple days..
> Bigmac
>
>
> On 5/21/06, C Boyko <roccit_53@scirocco.cs.uoguelph.ca> wrote:
> >
> > On 7:17:22 pm 05/21/06 "Brian McGarvey" <bmcgarvey@gmail.com> wrote:
> > > Cathy,
> > > Check your fuel pressure..or you may need to upgrade to larger FIs or
> > > a bigger fuel dizzy..
> > > bigmac
> > >
> > ?????? It's a 1.8 dizzy, and the engine's a 1.8. And pressure's
> wonderful,
> > top of the spec. (new pump). But I want to dial in the mix, and wondered
> > if
> > rich at idle's okay if it's at stioch otherwise. Vaccuum changes at
> idle,
> > so I'd assume mix does also. I haven't touched the mixture screw on the
> > dizzy at all at this point. So, why are you suggesting an equipment
> issue
> > here? Just curious, I'm sure there's room to richen it, I doubt it's
> > topped
> > out or anything.
> > cathy
> >
> >
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