Quote:
Originally Posted by mwebb
[COLOR="Blue"] ...on a speed density system
with a MAP sensor as primary load sensor
a vacuum leak will result in rich condition with retarded ignition timing
NOT lean condition with advanced ignition timing
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Correction, it will result in a stoichiometric condition as long as the system can compensate for the additional air via the o2 sensor (and updates the trim values, etc). Coyote and others have noted that their cars are basically "pegged" on the "try to add more fuel" side on e10 as the ecu tries to bring the mixture back to stoic (14.2 ish for e10). Once at the limit of the system to compensate, any additional bypass air means leanness.
Though their spark plugs should be pretty clean if they are constantly lean.
It may also be a function of "driving on the o2 sensor", i.e. the internal maps are targeting 14.7 for the fuel schedule and the o2 compensation algorithm just kinda sucks when you get to 14.2 (large mixture "ripple")
EDIT: Nery's what fuel injections system(s) do your cars employ, all TBI by any chance?