[T3] Lean Cruise

[Jim Adney]

On 9 Mar 2013 at 8:40, Max Welton wrote:

> I work at 6000' and live at 7500' and was running VEAL in both
> directions. I found that VEAL was leaning-out the VE table in one
> direction only to enrich those same cells in the other. That stopped
> after I added the second sensor. 

Wouldn't the fact that you were going uphill in one direction and 
downhill in the other explain much of this. But that wouldn't explain 
why the second sensor made this go away.

> As far as how this plays into the fuel equation, I'm going to refer to
> the Megasquirt documentation. 
> 
> http://www.megamanual.com/v22manual/mfuel.htm#equation

Wow, that really gets into the nitty-gritty of things. I can see that 
you've put a lot of effort and thought into this and I'm really 
impressed. It sounds like fun, and just a bit tempting....

The link above seems to say that the second barometer is useful 
because it can take into account the difference in exhaust 
backpressure. IIRC, they say that this would be especially important 
if you're turbocharged. Are you?

I assume you're firing in 2 banks. Can you use the D-jet trigger 
points to trigger the MS? I find myself wishing that the trigger 
point cam advanced with the mech ignition advance. Do you think that 
would have been useful?

The '72-3 D-jet distributors have the FI trigger point cam advanced 
by about 30 deg. I think that feature could be swapped into any FI 
distributor. VW claimed that it made for smoother running, probably 
at idle, but I've never really noticed any difference. Once you get 
warmed up and up to speed, it doesn't seem to matter whether the gas 
sits behind the intake valve for a bit or not.

-- 
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Jim Adney, jadney at vwtype3.org
Madison, Wisconsin, USA
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