IAT Spark Advance Correction Table

[Munch]

What is it and how does it impact the normal timing of the motor?

The reason I ask is this: HSW has a timing controller for their nitrous kits in which you can set it to pull timing when spraying. According to them it will pull up to 3 degrees of timing on the LS1.
They also add:

The Interface uses the IAT Spark Advance Correction Table in the PCM for retarding timing. The Interface is limited to the values entered into this table, so if you would like to pull more timing then what is available for your application you can do so by modifying the IAT Spark Advance Correction Table.

[Y2Kvert4me]

That is a spark timing modifier table which will retard spark when IAT gets high enough.

On a stock tune, this table is basically irrelevant until you start seeing around 100° intake temps, then it will gradually pull some timing to compensate for the hot air charge entering the engine. The hotter IAT gets beyond that point, the more timing is retarded.

More than likely, what you are describing is basically altering the actual IAT value sent to the PCM to cause it to read high and pull some timing to compensate.

If it's only triggered with the spray, I can't see why it wouldn't work effectively.

[Munch]

So what about a non-stock tune? (heads / cam) Are these values altered for any reason or are they solely for use in high IAT situations?

I don't know what my timing is set at now but I'll find out before I actually start this whole project and I doubt I would need more than the 3 degrees (if that) for my application but, let's say you did need to alter the values in this table and then were out driving on a day when temps were 100+... what then?

[Y2Kvert4me]

Originally Posted by Munch

So what about a non-stock tune? (heads / cam) Are these values altered for any reason or are they solely for use in high IAT situations?

I don't know what my timing is set at now but I'll find out before I actually start this whole project and I doubt I would need more than the 3 degrees (if that) for my application but, let's say you did need to alter the values in this table and then were out driving on a day when temps were 100+... what then?

Doubtful that table was modified in your h/c tune. There's really no need to, as it's just a modifier that only comes into play when the intake air is hot. It's not setting your normal timing, but will pull some when in very hot conditions.

Without knowing exactly how this interface "interfaces" with the PCM, it's tough to say if the normal IAT correction is still employed when spraying, but based on the note that you can still modify the table to further change the intended 3° retard, it would seem the table does remain fully functional and would still do it's job in hot weather too, meaning if you hit the spray and get a 3° retard on a cool day, you should get more pulled on a hot day where it would already be retarded some because of high IAT.

[Munch]

Gotcha!

Thanks