93 octane

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#11

08-21-2007, 02:07 PM

finch13

Been Around A Long Time Member

Join Date: Jun 2007

Location: St. Paul, MN

Posts: 7,381

RE: 93 octane

Quote:

ORIGINAL: JimBlake

Quote:

ORIGINAL: smaglik

why will the v6 respond and the i4 wont?

Without better information, I can take a reasonable guess..

The 4-cyl ECU has maps for spark timing & mixture over the operating envelope of the engine. The knock sensor can retard the spark from that map, but the ECU is probably not programmed to advance the spark beyond the map. So if the knock sensor is NOT hearing any knocking, it won't go hunting for the point of incipient knock.

Maybe the spark map for the V-6 is set up with enough advance so that the ECU has to pull back the spark when it has 87 fuel?? I was not aware that Honda would have done this...

Actually the ECU from the 95 4 cyl doesn't have a knock board in it, and thus, no knock sensor. Also, the ECU only uses the maps stored on its EPROM when it's in open circuit mode (i.e. flooring it). While in closed circuit it uses data from the sensors, o2 especially, to adjust the a/f mixture. I believe both engines respond, the v6 responding more because it is in fact a bigger engine and the I4 response is not as noticeable. 93 octane has 6% more octane than 87 and octane produces the most power in gasoline.

#12

08-21-2007, 02:09 PM

finch13

Been Around A Long Time Member

Join Date: Jun 2007

Location: St. Paul, MN

Posts: 7,381

RE: 93 octane

Quote:

ORIGINAL: noboundaries6289

i have the same type of car with 175k on it as well. I use synthetic oil with no leaks and use premium fuel. Personally, I never got a chance to know what 89 octane performed in it. I put 93 in it since I got it. No smoke, No knocks, i'm happy with it.

Same car, 225k, always used 87, no smoke, no knocks, i'm happy with it.