Humidity spark tables

[Clutch]

Opps! Sorry I understand the concept of how it works; I just wrote that up wrong. It's fixed now; I think LOL...

Anyway, my point is that if GM has it set up right; weather you're tuning on a "more humid" or "less humid" day these tables will compensate for it "for you" while you're tuning on that particular day and also compensate for changes in the humidity forever after the tune is done. If you zero out the table or modify it, then you're not taking full advantage of the reason it's there in the first place, to optimize the spark under "all" humidity conditions. Just sayin...

[TriPinTaZ]

The OEM GM Humidity Spark logic is no longer optimal once you start tuning the car and changing spark & fuel. So you have two correct choices. Adjust the humidity to fit into your tune or zero it out. There are use cases for both options.

[Clutch]

At the track going for your best time; sure, zero it out and make changes in the tune to get the best performance. No argument there.

I want to qualify my opinion on this is for a tune that will be put on a daily driven streetcar. Perhaps a customer's car or even your own. Point being a tune that will stay in the car and not be messed with until future mods are made.

As you know it pretty humid down here in SW Florida most of the time but there are days when dryer cooler air makes its way here and that makes for a good day to go for a blast. I had tuned my 97' (pictured) and that day came. Went for a blast and car ran awesome but it did pick up a bit of knock. So, I wound up pulling a few degrees of timing to keep her happy. If the tune had the ability to adjust for humidity like my 2015 Z06 does, I wouldn't have had to manually change the tune.

So...My contention is this. Having the ability to tune for humidity is beneficial and can offer the best performance in all conditions.

Stepping down from my soap box. LOL

[TriPinTaZ]

Sorry, I'm confused by your posts. It sounds like you're trying to convince us that humidity spark logic is viable, which is what we've been saying in this thread. Or are you confirming you align with our consensus? Not being rude here, I'm actually confused lol.

[Clutch]

There was no consensus. There were multiple posters saying they just zero it out. I was just giving my opinion.

[engineermike]

I’m jumping through hoops on my ford to get humidity spark logic to work on a coyote and gm guys are zero’ing out the humidity tables they already have! Seriously though, I’m finding I can run up to 3 deg more timing in humidity than dry, and that’s 50-60 hp without having to reflash.

[Clutch]

I'd like an explanation on how "Humidity Spark logic is no longer optimal once you start tuning the car and changing spark & fuel". I'm pretty sure it doesn't change the physics of how flame propagation works in dry vs. humid conditions. So, what is it then? What are we talking here, 1 degree?

[TriPinTaZ]

I'd like an explanation on how "Humidity Spark logic is no longer optimal once you start tuning the car and changing spark & fuel". I'm pretty sure it doesn't change the physics of how flame propagation works in dry vs. humid conditions. So, what is it then? What are we talking here, 1 degree?

Because I often increase the base timing when tuning a car, so I'm already at or near peak timing in humid conditions. Then I only remove timing for dry air. As I've mentioned, I tune for cars in Florida and Texas mostly so this logic works for me. It is easier to account for maximum possible timing this way. This may not work well in some other areas that often have large swings in humidity. As I've also mentioned, I often only adjust this for WOT conditions and maybe adjust a few peaky areas for part throttle. The amount of timing that I allow to be removed depends on the setup and where the car is located. There have been a couple of cars that I have allowed the Humidity Spark to still add in some situations, its just not usually the case in the more southern states in North America.

If I want to target 25 degrees at WOT in humid air and 23 degrees at WOT in dry air, the OEM Humidity Tables are not setup to match what I want. So I change them.