There is no learning for the octane. The knock sensors fire off when they
hear noise and the timing is immediately retarded. The new timing numbers
will automatically be adjusted no matter what or when. Assuming you knock
sensors and the code strategy is up to it.
Now the less btu content of the higher octane will have a small change on the
learned tables by requiring a slightly richer mixture when in closed loop.
But the O2s will adjust to the proper 14.6 AF ratio then start saving new
values to the adaptive tables immediately.
But the WOT tables are fixed and therefore without adjustment you get what you
get. Stock tables are way rich anyway for open loop (on the V8).
I've always gotten a bit better mileage from premium, ~1-2 mpg, but cost wise
it's a draw.
I do see an advantage to using premium when the ambient temp is above 80F as
the timing will stay higher.
Paul
On 7/5/2006 12:21:12 PM, Juillerat, Aaron J (aaronj@autojectors.com) wrote:
> Drive like you normally would that is best. The computer will adjust to
> the optimum performance of the parameters
> it's faced with. Meaning your
> car was use to how you drive with premium, then all the sudden you
> dropped to regular and thus changing a parameter so it needs to learn
> what to do with the lower octane. You may even want to pull a battery
> cable off and clear the computer and let it start from scratch.
>
> -A.J.
>
> -----Original Message-----
> From: shotimes-admin@autox.team.net
> [mailto:shotimes-admin@autox.team.net]
> Sent: Wednesday, July 05, 2006 1:05 PM
> To: shotimes@autox.team.net
> Subject: Re: [Shotimes] Poor mileage
>
> Is that for the first few tanks, or do I always need to floor it?
> I'm
> usually easier on the gas than not.
>
> On Jul 5, 2006, at 9:35 AM, Rick Glass wrote:
>
> > It will improve after a couple of tanks, the computer adjusts for
> > stuff like that......just give it more than 1 tank and
> don't be
> > afraid to put your foot in it, if you don't get on it, it
> ain't
> > gonna run right.
> >
> >
> >
> > Rick Glass
> > '99 SF 98k
> Flowmasters
> Kirk'd
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