Hello all, I am new to this, still learning but very excited. I had a few things that i can't seem to figure out, hoping you guys could help me out.
1) scanner config: i started from a config i found in one of the forums, i think it was gmtech's then modified it quite a bit. I dont understand the difference between "sensor" and "PID" variables. I think that the "sensor" variables are generalized names of the data in a certain PID. Data seems to be identical, so i switched my entire config to looking at PIDs, am i missing something here?
2) On the LNF i notice 2 different PIDs for Airflow. MAF (sae) PID.16, which i assume is the reading of the MAF sensor. And there is another "VE Airflow" PID.2311, which i assumed is a MAP and IAT calculation of air flow, kinda like speed density does?
a) My question is at part throttle, even low boost, those match very closely, however at WOT MAF reading seems higher than VE Air reading. Is this normal? does this imply that i have a boost leak? The only part on the car is a Injen upper charge pipe, that couldn't changed the VE enough to notice it in these measurements.
b) which is the true airflow? should i follow MAF?
3) I am trying to be mathematical about tuning this, it is my first tuning experience, and i don't particularly want to damage it. I am struggling to understand these "load" pids and these "load" axis in the calibrations. For instance, there is a "Air Load" PID.2322, then there's "Absolute Load" PID.67, then there's "Calc Load" Pid.4. and all are different. Then the calibration axis have some obscure "percent load" unit, and most of them are different.
a) Which "load" variable are you guys using? I am leaning towards "air Load" PID.2322.
b) Whichever load signal you guys use, "air Load" PID.2322 in my instance, I am assuming this is cylinder percent filling, which already accounts for Volumetric efficiency? Since at a MAP of 100kPa, PID.2322 is less than 100% i assume that's right, any input?
Now to tuning.
4) I've been reading up a couple books by Greg Banish. He talks about optimizing spark by running a "spark hook" test. Basically on a load bearing dyno, at a given RPM, and load, change spark and measure torque output, repeat for different speed & load. The name "spark hook" is from the idea that as time advance increases, torque increases, up to the point that it plateaus, then falls off due to knock. Apparently this looks like a "hook", i don't see it, but who am i to question Greg Banish.
a) the question is, for a relatively stock LNF, did anyone try to find the optimum spark advance, for 93 octane for a few points? Is anyone willing to share such findings?
5) cam phasing; from other threads i got the idea that during a warm idle, both cams are "parked", exhaust at -6 and intake at +10?
a) does that imply that at idle the engine is at minimum overlap?
b) as the exhaust cam value increases to a positive number, that means the exhaust cam "retards?
c) as the intake cam values decrease to a negative number, that means that the intake cam "advances"?
d) if the above are true, that means that if either (or both) cams move off parked, they both go towards increasing overlap? This seems a little different from some of the literature i've read that made it sound like usually both cams move both directions.
6) My first attempt to tune was to take the stock tune and add all GMPP stage tune values that we have access to. This got my MAP as high as 248kPa, 21.9psi (MAP-baso) at 4000 rpm, 3rd gear pull, 24 deg C inlet air temp. I thought the GMPP stage kit boosts to around 20psi, did mine boost too high? or is that normal?
Thank you for your patience with me, i'm hoping that eventually i'll catch up with you guys and be of added-value to the forum.
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