I 'believe' that the ECU can only change timing in this way if there is/are knock sensor[s] and it's connected to them and set up to do this.

Mike

----- Original Message ----- From: Jennifer <ncc876@YAHOO.COM> To: <vanagon@GERRY.VANAGON.COM> Sent: Thursday, June 14, 2001 1:14 PM Subject: Re: Octane

> At 9:33 AM -0600 6/14/01, Richard A. Jones rearranged electrons to say: > > >>>In Texas and New Mexico ALL of the regular gas > >>>was 86 octane. Anyone know why this is so? > > > >Regular is 86 here in Colorado. I've been told that > >the refiners lower it because of the altitude. I have > >noticed 87 at lower altitude places.... > > Gasoline has different octane ratings because the different levels > inhibit premature detonation before the spark plug fires (knocking). > Since this can damage the engine, it is important to put the proper > octane gas in your car (see the owner's manual for details) > > At higher altitudes, there is not as much oxygen in the air > (explaining why people get winded more easily in places like > Colorado) and thus it is harder to ignite gasoline. For that reason, > it is not necessary to use as much octane in your motor fuel. Most > manuals are written to assume you'll use your vehicle at altitudes > around sea level because most inhabited areas of the US are pretty > close to it. > > Feed your car the wrong octane level, and chances are the ECU will > inhibit your ignition timing to prevent knocking and cylinder wall > damage. A friend of mine came to me asking why his Camaro "isn't > making Mustangs shrink as fast as usual" and I asked him some > questions, including what gas he was using. It turns out he was using > 89 instead of the recommended 91 -- and his own engine was slowing > down to prevent expensive damage later on. I think this was the > 8-cylinder engine... > > Not enough time has passed to know if switching back to 91 octane > solved the problem, but I suspect that it will. > -- > > ----- > > Jennifer - ncc876@yahoo.com > ... knee-deep in the hoopla ... > > _________________________________________________________ > Do You Yahoo!? > Get your free @yahoo.com address at http://mail.yahoo.com > >