Another: what base map

[Centripetal]

I had originally used the "93 octane, intercooler" base map but I was getting 4 degrees of knock retard on all cylinders on my first pull. Since I know the gas can be tricky in New England, I switched to "91 octane, intercooler" and have seen very little knock retard.

2017 Civic Type R
Mods:
Mishimoto Catch Can
PRL FMIC
PRL HVI

Octane: 93

Location: Massachusetts

[Centripetal]

I'm a little disappointed that Hondata didn't reply. I was hoping we could open up a discussion to benefit the community.
Unfortunately, I got impatient and figured it out why different 93 octane gasoline has different knock retard. With winter gasoline, I no longer have knock retard and I did not have to modify the 93 octane calibration/base-map. Consequently, If enough people want to understand this, I will spend the time to write it up.

Hondata, could you please provide the following information so I can determine the exact thresholds such that I can dial this in. The context is the conditions while developing the 93 octane calibrations.

• Origin(s) of the 93 octane gasoline used
• The ethanol content of the 93 octane gasoline (if known). For example, in California, the ethanol content in gasoline ranges from 5.6% to 10%
• Ambient air temperature
• IAT temperature range

Hondata, if you'd like more of technical details, please send me an email.

[Hondata]

In you first post I did not see a question to answer.

For the your next questions, the short answer is that if you get knock retard on a 93 octane calibration and you don't get any on a 91 octane calibration then the 91octane calibration is what you should use.

Gasoline varies from station to station, supplier and time of year. That's why vehicle have knock control. I'm not sure that getting into the exact brand of fuel and temperature at time of tuning is going to help, since the ECU adjusts for temperature and the gasoline varies. In CA only a small number of 76 stations have 93 octane, but if you start to dig deeper than that you have to look at where the gasoline was purchased (a lot of purchased on the open market) and what refinery was used, and then what time of year. I don't think anything useful would come out of that research.

It's probably better to look at why your vehicle was retarding the ignition. Intake temperatures, fuel trims, gasoline source.

[Centripetal]

Thank you for your reply.

It's probably better to look at why your vehicle was retarding the ignition.

I couldn't agree with you more. Consequently, I am using the 93 octane calibration fine now with no knock retard (with winter gasoline) because I understand why.

I'm sorry, I should have been more specific about my request. I'm not looking for the brand of gasoline. I did not want to assume it was 93 octane from California.

I completely agree. Cars adapt to temperature of the air in the intake as well as how much fuel is needed to reach stoichiometric ratio. As I understand it, knock control is more of a protection than closed loop adjustment for fuel. However, there is a property the car cannot directly measure—far as I know—that greatly affects knock, especially on DI engines. Therefore, the ECM/ECU cannot adjust for it, which is why some 93 octane (AKI) gasoline will have knock retard. I guess in the end it actually does adjust for it by detecting knock but more as a reaction.

You have a really great product and support. Thank you for your time. I shall not take your time on this subject any longer.