I really appreciate what you're doing even though I don't truly comprehend it. But I thrive to learn anything technical. Thanks for trying to educate.

 

I actually really enjoy trying to help others learn - of the info above, what can I help you understand?

 

Well, turns out I was being dumb and scorched a bunch of plug wires. I didn't see the damage as they were under fiberglass sheathing. Anyone interested in a quick heat transfer post on what happened, why it happened, how it could have been avoided, and what the best way to go about shielding your plug wires would be?

 

Hey fellas, I'm back. Truck is up and running! Base tune is alright, nothing too special at the moment - just the standard air charge tweaks and spark checks at the moment. Current calibration is safe to about 13 lbs on 91 with the GT45 - I would have preferred 93, but I'm dealing with what's local at the moment.
Found a couple small mistakes with the injector characterization that I got worked out quickly (didn't account for the difference in fuel density to Stoddard fluid causing a global lean condition, was hitting injector turn on time limits during deep decel) so after head studs, gaskets, and a larger pump I'll be dropping the Gen 2 78/75 on for some more fun.

Next steps are to get the indicating system figured out. Thermocouple modules are completed (will post pics later), WBO2's are back at the manufacturer for diagnosis, analog inputs are still a WIP, and I can finally start working on the combustion stuff.

Here's the tricky part. I've been looking around at companies that would be able to Xray the heads so I can figure out where to tap the transducer and have come to the staggering realization that xraying metal is kind of expensive...the most recent quote was $900 for a single shot of the deck. I already tried to sneak a head in with me when I got my elbow xrayed (smashed it while mountain biking...) but the tech wasn't having any of my shenanigans.
Anyone know an Xray technician near Minneapolis that could help out?


Also, a question for the HPTuner guys out there - why is it that I rarely/never hear about people messing with the intake charge temperature bias tables? I'm talking about the multiplier table that gets applied to the model that spits out the modeled temperature at the back of the intake valve. It has a fairly significant impact on a bunch of different stuff, but I rarely see anyone touch it.

 

I’ve tuned charge bias, not everyone talks about everything they tune. If you tune that table be prepared to re tune your whole VE table, every setup is different concerning that table.

 

You sure it wasn't the penguin on your keyboard that did it accidentally? Lol

Certain things can only be calibrated on a bench in a controlled lab environment, and further that calibration lends itself to a level of modeled charge accuracy that is beyond the requirements of anyone simply looking for more power...something tells me this guy should know that. I love feigned humility

 

Well, to your point, I did come off as being a little arrogant with that last question. I suppose I should have worded it to read as such:

How are people setting up their charge bias tables, if they have ever touched it? I rarely ever see this included in build threads and was wondering how people are gathering the model output.

I also should have mentioned that I get bothered by little stuff revolving around drivability and run quality. I'm aiming for stock-like or better-than-stock run quality since I have the chance and setup to do so.

I don't have any visibility on the actual model or how the outputs are processed in the software but I was planning on trying a few things as I'll have a temperature probe close-ish to the valve but out of the spray. There are ways that I can reach a pseudo steady-state environment in-vehicle as well, I just need an intake drawing ambient. I figured this would be important as I've significantly changed the intake system and moved the IAT sensor way upstream from the normal position.

I don't know how different things, such as EGR flow, affect the model output - I'm looking for someone that has actually been able to find and log the output of the air charge density model. It doesn't hurt to ask how they may have done it.

Given your knowledge, terminology, and location, I'm inclined to believe that you may have some insight to the charge temp model though - care to share?



03sierraslt, what kind of process did you go through to modify the charge bias table?

 

If you can get a sensor to measure actual temperatures before the injector tip, you can calibrate the model directly. However for the layperson who wants to calibrate airflow temperature bias, things are far more difficult. You can't rely on fuel trims for feedback because for one, the error deadband for populating the trim values is too wide, but most importantly...temperature affects airflow and the resulting airflow is an input to the temperature estimation. So it becomes recursive. It can only be properly calibrated in a lab where you're not using onboard feedback as your metric for calibration. There are some complicated math techniques that can work, but they take a long time, won't be as accurate as a lab and again are not feasible for the layperson.

I only make changes to that model if I'm both 1) not running a MAF and 2) have issues that fuel trims are always chasing. Then I would look at what material the intake manifold and intake piping are and what connection they have with heat sources and then what sort of heat transfer properties they might have to the incoming airflow. If the manifold is rough cast aluminum, I would bias the temperature more heavily to coolant temp at lower airflow until I can see the response in the fuel trims. But I will say that I've never had an actual drivability issue that was directly related to air charge temperature biasing...it has always been a cosmetic issue that I could see in the data but not feel.

 

agreed, and I don’t have a lab. I spent the better part of a year pissing with this table randomly and comparing changes to effects on after start enrichment, heatsoak etc. My initial goal was to learn and I did, I also made some changes that proved to help with consistency in speed density applications. However every setup is different.

 

My 2 peas in this pod:

my 02 Tahoe is speed density on a 2bar OS and I've been live in person with my tuner for every session of tuning. He has never messed with charge temp bias that I have seen.

my educated guess is that he didn't mess with it at all

that was ~50k mi ago if I recall correctly. And she's been returned several times as blowers come on and off, cams change, trans parts change, gears change. I've always felt my truck started as nicely as stock and runs as nicely as stock down the highway. Mpg has suffered as my truck has been built, but I can't expect my tuner to fix bigger tires, shorter gears, added bumpers and skid plates and fuel tanks lol

so anyway, take it from the guy who has ~50k mi on a SD tune from sea level to over 10k': it will run great and if you feel something out of the ordinary, it's probably a problem with a local table (VE and spark) vs the global table: imo