Pulling timing for high IAT

[LAGA]

When an ECM pulls timing for for high IAT, how many degrees of timing is considered to be a lot?

 

[MrHorspwer]

It is typically not a set number. It is usually a function of IAT and engine load and varies based on the operating parameters.

I'll give you the two examples I have:

P01 PCM from 2000 Chevrolet Corvette:

At most, it will pull 9 degrees of timing, but that is at 194 F IAT. Looking through my logs, even on 90+ degree summer days, I've never seen IAT above 110 degrees. At that, the max it's pulling is 3 degrees starting at 50 kPa MAP. At IATs under 94 F, it doesn't pull anything.

E92 ECM in 2016 Chevrolet Colorado:

At most, it'll pull 8 degrees of timing at 198 F IAT. Going by the same 110 degree IAT as above, it's pulling 4 degrees max. The E92 uses airmass measured in g for engine load (which is a calculated value, not a direct measurement like MAP kPa). It does start pulling timing at 90 F IAT, where it'll pull 1 degree.

Both of these are directly from the calibration pulled with HP Tuners.

 

[benjy]

its amazing the difference REALLY cold air makes on the tuning while driving + especially on a boosted engine. looking at my boost gauge driving to work at 0 to 20 degrees my little port injected tuned 1.8T VW engine really hopped compared to milder temps. tuning likely allows more aggressive timing as well. my cold air intake filter was about 6" from the ground in my fenderwell + really worked!!! a fun drive from a cheap 30 mpg car, something not possible in the "good old days"

 

[LAGA]

I brought my 05 Edelbrock superchargerd Mustang Gt in to the dyno. I have a custom datalog tune now and just wanted to se what of power it makes. It was 92°F and the engine was completely heat soaked. I had IAT of 173°F and the tune pulled 16 degrees of timing. It was a Mustang dyno and the car did 396 RWHP. The dyno guy said considering the conditions, it did pretty good and he wouldn't change anything. I wasn't there for a tune just testing.