Hi Guys,
Sorry for my dumb questions, but I'm a noob...
I have several issues I'm trying to understand.
First one is :
I first installed an AFE CAI and ARH LT headers on my 2017 C7 GS 1 month ago. I bought a wideband O2 sensor to monitor how the car would run with stock ECU program. It was running at 0.89 Lambda at WOT, a little lean. Since the tuner I was planning to use (JDP Motorsport, Salt Lake, UT, HPtuner) was 3 month out for a dyno tuning, I bought Diablosport Intune ( I know should've bought HP tuner, perhaps will do it) just to be able to adjust my fueling to be safe in the meantime.
I had to add around 5% of fuel at WOT to go in the 0.85-0.86 lambda range.
Then I installed my MSD Intake manifold last week end. Very strangely (at least for me), with the same tune (stock tune with 5% more fuel) the car ran a lot richer 0.79 Lambda at WOT. I completely don't understand....I had to go back to stock fuel map to go back to 0.86-0.87 at WOT... How it is possible with a manifold that has more volume and flows better ???? When I look at my absolute intake manifold pressure it is the same as barometric pressure....and same or slightly better than stock manifold. My MAF values are a little higher than before ... (around 330-335 g/s at 3000ft, saw a pike at 346 ) It doesn't seem I have a leak as I would run a lot leaner with a leak, my idle is stable, driveability good (though it seems I have lost in throttle response and little torque low)...
Second one is :
I completely don't understand how works the timing on this car... Here are 2 datalogin 15 min appart. First i have between 20 (high rpm) and 23 (max torque) degrees of timing ( 91 octane, around 3000ft elevation) . After 15 min of sport driving (mountain road) but with same intake temps, same fuel same elevation, only 12 degree at high rpm and only 15 deg at medium rpm. No knock retard at all.... What the heck ??? The more i was driving the less timing I had it seems... The car felt definitely way slower at the end with low timing...
Datalog 1.jpg
Datalog 2.jpg
Any insight would be appreciated, as I don't understand at all...
Thanks guys