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Old 05-18-2011, 01:58 PM   #33 (permalink)
abogart's Avatar
Join Date: Mar 2011
Location: Michigan, USA
Posts: 50

EcoCorsica - '96 Chevrolet Corsica Base
90 day: 32.01 mpg (US)
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Originally Posted by dcb View Post
A reasonable explanation why WOT is not more efficient at making power than %75 throttle on a gasser may be that the cars computer goes into enrichment mode at WOT (the obd port MAY indicate open loop operation under these conditions as well).
I have observed this using Scangauge. Not sure of the actual TPS value, but it was definitely somewhere between 75% and 100% throttle opening. Loop goes to OPEN and AFR (air/fuel ratio) drops to 12.5 from 14.7.

Another reason that higher throttle settings may not necessarily be more efficient is fuel's resistance to detonation. I have observed while running regular 87 E10 fuel that the engine's knock sensor will detect detonation and start retarding ignition timing under as low as 23" Hg manifold pressure in certain cases.

Check out this thread for more on this subject.
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