Ken,

As I’m sure you are know, the Gen II Lightning’s make huge amounts of additional HP when the ambient temperatures drop and the charge density increases. The change is so dramatic that some Lightning owners feel it is not safe to run the same tune year-round.
They believe the WOT fuel and timing tables are immutable fixed values and going open loop with cold air temperatures puts you at risk of running lean or detonation. To compensate they pull back timing and richen the fuel on their Predators until spring.

I know the MAF and IAT sensors provide information to the Predator re-flashed EEC to keep it running stoichiometric during closed loop. Since I’ve been open loop with temperatures in the 30’s and not seen any detonation I believe the ECC probably modifies or scales the WOT fuel and timing tables to compensate for the changing conditions.

Who is correct?

 

You're both right.

First, what's common is these vehicles can vary quite a bit. Two chips with the same tune on different trucks can have different a/f ratios (which explains why you may hear one person praise their programmer and other says the very same guy sucks). The only solid way to know is with a dyno and a wideband O2.

Now... some details. Even at open loop the Lightning's PCM is not ignoring air temps. The PCM has a fuel multiplier table for WOT based on air temp. Additionally, there is a spark table specifically for WOT, and a spark table multiplier for air temp. This is not to say that spark knock or lean conditions can't happen. There are a variety of factors, such as fuel octane, and some areas change fuel blends in the winter to oxygenated fuel which can cause the vehicle to be more prone to knock. What works for one guy in one part of the country may not work for someone in another part of the country. DiabloSport did a lot of testing on the tunes to insure safe ratios. The majority should not experience problems.

If you want more details, such as table specifics, I can give that....

 

Thanks Ken,

Knowledge is a good thing! I’ll gladly read all the details you have the time and patience to share.

 

Let me clear this with Diablo and SCT first. I don't want to break any non-disclosure agreements....