Update: Closed Loop Disable in $6E

[Shannen Durphey]

Yep, I've spent bunches of time watching this in Vettes.  The tuned port cars
just love a six speed, 'specially on the highway.  The torque curve is waay
down low in those cars.

Cam timing sounds like a good cause.  So does ignition timing.  If you've
backed ignition timing off due to ks activity, you could be fighting
yourself.  Cam can still make plenty of cylinder pressure, but now spark isn't
optimum.  Chamber design, octane, cylinder head temps, yadda yadda.  

I've seen rear gears changed from 2.73 to 3.73 and mileage actually increases.
Big cam, big car, had few other hi-po parts, and wrong gears.  You're at a
really, really low rpm, and it takes more work to get things right. 
Went from 2.26 to 3.08 in a big block car, mileage dropped from around 16 to
10 mpg.  Wrong cam.

Look at your spark and fuel maps.  They can give you a clue where the torque
peak of the engine occurs.  One suggestion might be trying different size
tires.  Even changing pressures can make a difference.  Or find a new speed to
drive at. Sounds to me like you'll get best mileage around 85-90 mph.  Plus,
you get through the tolls so much faster.
Shannen

Bob Valentine wrote:
> 
> This is something I've been wondering about for a while.   In overdrive
> cruise (70mph, about 1500rpm) tps is 11%-13%.   Drop it down into drive
> (70mph about 1900 rpm) tps drops to 8%-10%.
> 
> I don't remember the injector pw's right now, but I think they were
> slightly lower.
> 
> Thoughts?  I'm guessing the cam in the motor (unknown) just isn't in it's
> "good" area at that speed.   I've played with timing/fuel in this area and
> no real gains.
> 
> -> Bob Valentine
> -> bob at tecmark.com
> 
> At 09:29 AM 2/5/2001 -0500, you wrote:
> >>Go for changes for min TPS.   So far I haven't found an exception to that
> >>rule.   Just got to be anal about testing slight hills and it's meaningless
> >
> >Gotta agree there.  Less throttle at same speed = more efficient.
> 
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