[T3] Drove Hothe tonight.

[Keith Park]

Well I bumped the fuel pressure to 34, that brought the whole curve up to
reasonable AFR numbers after leaning out the partial load adjustment on the
pressure sensor, problem is... it wont track that well, it still tends to
lean under near or full throttle... will go up to AFR's in the 14's and low
15's when the cruising is around 12 or 13.  The Bucking at 1800 RPM seems
better with the late system, but it has still tried to do it a couple times.

I suspect I do need to go back to the earlier system, the one that was
originally used on the 2L porsche, it tracked better but had transition
problems as 1200 and 1800 RPM.  I can adjust the partial load and full load
mixture independently with that system.

Keith



> now remind me... what gives the full load enrichment on the stock 73
> T3 injection? I remember it being an extra pin on the throttle switch,
> but is that it?  you wont hit that till your floored. 

Yes, full load comes on via the 5th pin on the '72-3 TVS. Yes, that's near
full 
throttle, but that IS full throttle, after all.

Two other pins on the same TVS give extra injector pulses, same as on 
'70-1, to provide opening throttle enrichment, just like a throttle pump on
a 
carb.

I'd recommend tweaking the fuel pressure rather than the pressure sensor. I 
think that will give you what you want, AND is something you can measure 
and put back where you started if it doesn't pan out.

Recalling the trouble Daniel and Jessica went thru with their '69, when they

tried to tune via their air/fuel sensor, I'm reluctant to recommend that
route. I 
suspect that the Big Boys, the automakers, have much more sophisticated 
instruments, that are much better at measuring transient exhaust conditions.

It seemed to me that their experience indicated that under rapidly changing 
conditions, their sensor was responding to other things, in addition to 
air/fuel, other things like exhaust flow velocity and exhaust temperature.

I had a friend, a recently deceased engineering professor, who ran an 
engine research lab here at the Univ. of Wis. It was a pretty amazing place,

with instrumention you and I couldn't imagine, and none of it would have fit

in an actual vehicle, other than possibly a medium sized truck. Most of his 
work was funded by Ford, but I suspect that what Ford had in their own test 
labs, was even more impressive.

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

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