3 Attachment(s)
15 Silverado cam VVE/MAF calibrations issues/questions
First off, This is the one and only vehicle I've ever "tuned" or used HP Tuners on, so please bare with me and my rookie-ness. Yes, I'm aware a Gen 5 is probably the worst platform to learn on, but hey why not jump in the deep end to learn how to swim...
2015 Silverado 5.3L
Texas speed stg 2 (218/226, .635/.635, 113lsa), Factory fuel lobe, DOD delete
Texas speed long tubes, cat less y-pipe through a 3" exhaust with magna flow muffler
Stock intake box, tube and manifold with drop in K&N filter
AEM WB, using OBD port
Sunday I attempted to continue dialing in VVE, but the changes seemed to make it worse and ended in frustration. Drivability sucked, Error % seemed to be way off from the log before, so i decided to do a little more reading on the forums before I pushed the truck off a cliff.
My "normal" process has always been to let the vehicle get to operating temp before logging data to make changes by multiplying error % by 1/2 %, however this isn't the first time I've noticed a lean area change to reading the opposite, rich or vice-versa randomly during a log or towards the end of a drive.
With that being said, Hypothetically, my "average" error might be +/- 2%, however at the start of the log it was reading -10% error, and end +10% error. This cant be normal, so what variables am i missing??? SOI, IVT, injector temp?
Long story short, I read forums for the rest of the evening and found that VTT "can" be left stock with good drivability on "performance" applications.
Monday I decided to go back to MAF calibration (drivability has always seemed better while calibrating MAF and its "easier") so I started out by putting the Virtual torque tables back to stock 100% (only minor changes were made previously for idles areas) and to make some changes (slightly extreme) to Idle speed control reserve values to dial in idle and idle timing. To my surprise everything seemed happy in the drive way so lets take it for a little spin and see what happens.
Drivability was 10 fold better than anything I've experienced post cam install. See attached log, My timing advance was actually close to base advance which has never happens, throttle response was great, truck seemed to sound better as well, however there are still fueling issues... no big deal ill start making corrections. see log 3-22 maf 1 file
I then wanted to check drivability for calibrating MAP on the way back home, just to see if the it was the VTT giving me issues, BUT truck drive like crap again. Giant areas of the VVE that are off worse than previous logs, Timing is way to low, but as i keep driving the areas that were averaging mostly lean or rich are now reading to the opposite end of the spectrum by the time I'm getting home... mind you ECT was above 150* before logging so... see Log 3-22 Map initial
Again, i am aware that this is a Horrible "tune" and needs a lot of work but there has to be some variable I'm not seeing/paying attention to.
Do I really need to change SOI for this cam? if so, do i just use cam specs and math to find the exhaust valve closing point and then determine the "earliest" point of injection?
Are IVT and injector temps skewing my error %? what can i do to correct this if it is an issue? From what I've read so far, i understand the concept, but i have zero understanding of how the scanner needs to be set up or if it can be done in CL or OL?
Or am I just doing everything wrong? Most likely the main issue i am having, but I'm still to stubborn to bring it somewhere for tuning...
Any advice would be greatly appreciated, Thanks.
Colin
