Alright, I am now able to align data together from EGT & VCDS logs. Took what I used to consider some fancy Excel work and is relatively simple now that I've been crunching data (30K-ish data points since they don't know how to use a database) in Excel for work. Yes, the plots coming up are "bling" but they aren't ostentatious, I hope. Anyhow, this leads to looking at operating conditions and parameters and fine tuning my tune.
Notes about the Plot
The logs used for the following were pulled for the sake of looking at injection timing, IQ limiters, and EGTs. I stopped off as a pseudo-rest stop on the way home from work, change the N108 adaption a tad, and proceeded to do a 1-2-3-4 gear pulls on flat ground. After finishing a stretch of road a little over a minute later, I have a nice, long, elevated freeway onramp that I did a 4th gear pull out to 4000 RPMs and drove home.
RPM / 100 = Black
IQ derived from Limiters = Orange
SOI Spec. & Act. = Grey & Blue
EGT = Yellow
The first three are plotted to the left y-axis and EGT is plotted to the right axis.
The Excel file, aka log, is here (294 kib). You can change the time offset by modifying A44. EGT data copied from a separate file.
Click to embiggen:
Notes about the Tune
Timing map is the "standard" SOI map that stays BTDC from my tuner with a -1.9° adjustment applied globally. This was done intermittently due to troubleshooting my N75 map and is a stand in for greater modification due to the Diesel HPR fuel's Cetane rating of 75. Boost map is the modified/adjusted stock map from the 2.7l the GTB1756VK was fitted to. The N75 map is a custom one that I'd iteratively going through test-and-adjust on.
I have no way of verifying smoke output since the pull was at night, but given that I know I'm virtually a light haze to haze free during the day with similar test pulls, I'd expect the same. Boost is 2.2-2.3 bar absolute from 2500 to 4000 RPM in the tune, but with EGTs going up, I creep to 2.5-2.6 bar absolute.
Questions I have
Is it feasible to lower EGTs?
If so, will increased boost solve this even though I have no smoke?
What about SOI?
Should I open the vanes more via the N75?
I'm missing a PCP sensor (next year in Q2 maybe) and I'm on non-standard fuel. Opening vanes will decrease the likelihood of reaching requested boost (dependant upon PID control), increasing SOI increase PCP, increasing boost leans the AFR. All of these are acceptable methods to work by, but given that I'm at no smoke at ~20 PSI at "50 mg/str" I'm curious what action should be taken. Log the pump to see what voltage its at?
I'm looking to have EGTs peak at 950 °C/1742 °F, but then via "the tune," drop them to ~900 °C/1650 °F out to redline. Could I have my tuner do this? Yes, with a lot of trial and error and delayed back and forth and nit picking, but largely because I'm curious and I want to know how to do it myself.
Thanks for reading.
-DC