Tuning and high/low octane tables

[plastrd]

My Camaro has had a CAI since shortly after I bought it and this spring I'll be going for LT headers and HF cats. I'm thinking this is a good time for a tune (99% likely of the mail order variety) since I'll have to tune out the O2 sensor errors.
I run 93 octane all summer but in the cold months when I have the snow tires on I stick to 87. This arrangement has worked fine so far, between seasons I do the fuse pull after switching gas and I don't romp on it during the winter. Is a tuner going to be able to keep both octane tables when tuning for CAI/LTs?
The other option is put the stock tune back on during the winter and ignore the CEL light much like I ignore the TPMS light but I'd like the peace of mind that I'm not running too rich or lean year round.

[JANNETTYRACING]

Originally Posted by plastrd

My Camaro has had a CAI since shortly after I bought it and this spring I'll be going for LT headers and HF cats. I'm thinking this is a good time for a tune (99% likely of the mail order variety) since I'll have to tune out the O2 sensor errors.
I run 93 octane all summer but in the cold months when I have the snow tires on I stick to 87. This arrangement has worked fine so far, between seasons I do the fuse pull after switching gas and I don't romp on it during the winter. Is a tuner going to be able to keep both octane tables when tuning for CAI/LTs?
The other option is put the stock tune back on during the winter and ignore the CEL light much like I ignore the TPMS light but I'd like the peace of mind that I'm not running too rich or lean year round.

Yes You Can have it Your Way, Damn I Sound Like Burger King

[IndeedSS1]

Originally Posted by plastrd

My Camaro has had a CAI since shortly after I bought it and this spring I'll be going for LT headers and HF cats. I'm thinking this is a good time for a tune (99% likely of the mail order variety) since I'll have to tune out the O2 sensor errors.
I run 93 octane all summer but in the cold months when I have the snow tires on I stick to 87. This arrangement has worked fine so far, between seasons I do the fuse pull after switching gas and I don't romp on it during the winter. Is a tuner going to be able to keep both octane tables when tuning for CAI/LTs?
The other option is put the stock tune back on during the winter and ignore the CEL light much like I ignore the TPMS light but I'd like the peace of mind that I'm not running too rich or lean year round.

So far no one has given good reason to mess with the low octane table. Tell you tuner what you are doing and to not mess with it. I run snow tires in the winter and 93 all year round. But I would want my low octane table left alone or maybe only tweaked slightly, in case I get bad fuel or accidently the wrong octane.

[bluetorp]

I think there's a general misconception about the two spark tables and how they work. Forget for a second that these two tables are named "high/low octane" tables. Octane does not determine when the PCM drops into the low table- knock retard does. The PCM is blind to the octane rating of the gas in the tank. You can have 93 in the tank and be running on the low table, or 87 and be running on the high table; it's all down to how much knock the knock sensors are detecting. Running low octane fuel is just one of many things that can cause knock, which can drop the PCM into the low table.

If you run 87 in the winter, and are not driving aggressively, you're probably not getting much if any KR, so you're probably in the high table the entire time.

The only time the low table should not be changed during tuning is if the high table isn't getting modified either. Not tuning the low table is a hallmark of a lazy tuner. Other lazy things that get done to the low table: copy/pasting over the high table with no changes (Unless this is what you want and you are aware of it. It's a valid practice and some people prefer to run their cars this way), or copy/pasting over the high table and subtracting an arbitrary amount of spark from the entire table. A properly tuned low table should be pulling a good amount of advance in the high load cells, but should not be pulling much advance in the low load cells.