(2003) I partnered with Injection Logic, a small IT company working out of San Luis Obisbo and began developing what was the first Self Tuning Engine management system.Originally Posted by Hondaeater
(2003) I partnered with Injection Logic, a small IT company working out of San Luis Obisbo and began developing what was the first Self Tuning Engine management system.
When I download this file, it comes back as being corrupted. Anyone else have this problem? I would like to mess around with the model to see how it relates to the values I have in my PCM currently.
Are you using simulink? If you use Octave, it can't open slx files.
Try it again. Seems to work now. Have to do a little dance with the file extensions to get it onto the website... Change file extension from csv to zip, then unzip it...the slx will be inside.
Last edited by smokeshow; 04-26-2023 at 05:48 AM.
So like I was saying...
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Last edited by SiriusC1024; 04-26-2023 at 05:05 AM.
Watch the video again. The piping of the air conditioner super cools the water of the water to air intercooler on the supercharger.
This actually cools the air going into the motor, it doesn't trick it to think it's cooler air it IS cooler more dense air. It's not a new idea for Dodge but effective!
https://www.roadandtrack.com/new-car...ng-power-tech/
2017.
https://www.autoweek.com/news/a20955...e-performance/
Funny 1993 had this tech, yet the IAT principles are the same regardless.
I saw that but he did not go into detail but that makes perfect since.
TL;DR
Jeeeeeeeezzzzz... Leave me out of your drama.
1) IAT is not optional, more specifically, MCT (Manifold Charge Temp, or the temp of air actually entering the cylinder). Getting MCT right usually requires some creative blending between the measure air temp and coolant temp. Where the air temp sensor is placed has a huge impact on this.
2) I'm not sure how you guys intertwined PCV and IAT discussions, nor do I care to go read every line to figure that out. I run a proper PCV system on every boosted car I do. Just because someone thinks their engine "ran just fine without one" is not sufficient evidence on its own to discount the engineering reasons behind doing it right.
3) It's entirely possible for each of us to have offline conversations where we completely agree on another topic that has no impact upon some random future thread on a forum. There are lots of smart people on here. I like working with them on cool projects. If you really want to help me now, buy my new book or hire me for training and consulting.
Maybe I'll stuff some of these topics in my list of potential future articles for Hot Rod. Be nice and stick to the science, folks.
Nice plug, Greg. lol
So like I was saying...
Engine>Airflow>General>Cylinder Charge Temperature
If lean - bias 0lb/hr cell toward IAT
If rich - bias 0lb/hr cell toward ECT
or
Relocate IAT closer to the intake valve and compensate toward IAT in the tune.
Last edited by SiriusC1024; 05-10-2023 at 06:16 AM.
FWIW, I was have some warm start idle issues. I wound up adding 2 degrees of timing to the idle advance table and also tuned the base idle airflow table. My warm start idle issue seem to be gone now, but we haven't had any really hot weather yet. Still waiting to see how it holds up in 95 degree ambient air.
What is your idle speed and idle advance? I'm at 31 degrees and have bumped my idle up to 920. I would like to get this a bit lower, which should be possible with a stage 2 cam. But for now I'm warm starting okay.
When I added the 2 degrees of idle timing, the cold start idle was not nearly has happy. I could not drive the car until after it was fully warm, otherwise it would stall. But after tuning the base idle airflow, it now runs well. If your base idle airflow isn't set right, the computer is going to be making adjustments to fuel and idle timing. Both fuel trims and idle timing trims will be in play. Try to get those to near zero and things will be happy. You'll want to log LTIT, STIT, and the short/long fuel trims. Also log desired idle airflow (this is what's used to tune the base idle airflow).
31* sounds like a LOT of timing for idle on an LSx. You need to be a fair amount retarded from whatever the true MBT timing is at idle for your combination so the idle control (over/underspeed) can work correctly. Retarding the timing reduces idle torque, which should slow idle speed down and create a torque reserve from which the ECU can grab additional torque if needed to prevent sagging RPM later.
I just read through 5 pages of mostly garbage and nobody mentioned the actual problem. You can't properly model cylinder charge temps unless you have a REAL air temperature reading from somewhere. Under low airflow conditions, the iat sensor is giving the temperature that the sensor body has heatsoaked to instead of the actual air temp. Smokeshow explained how GM works around this with their combination of multiple airflow models, bias tables, and plain old o2 sensor corrections. I would like to know what iat sensors have the best ability to read actual air temps vs the temperature of whatever housing they are plugged or screwed into. Just a couple of hours ago I was working on a tune where the actual outside air temp was around 70f. Sitting in a parking lot to flash a new tune took long enough to cause the iat to read over 120f. In 5 minutes of driving at highway speed it was still reading 95f, even though the real air temp going past it was barely over 70f. Running CL would make this a non-issue for normal driving, but leads to chasing your tail in OL trying to tune the VE.
If you're having problems try adjusting IAT vs ECT bias.
ect iat bias.png
That table models the difference between the iat sensor reading and the actual charge air temperature going into the cylinder. It has nothing to do with the iat giving a false high reading that does not correspond to the real air temperature. Also, the first time I typed out a response and hit reply it did not show up.
I know what it has to do with and doesn't. It's a workaround. The idea behind it is to "pay less attention" to IAT at low airflows. At higher airflows the air intake tract will have less temperature gradient.
Look at how the sensor is constructed. See that tiny little bead held out on fine wire? It's not heatsoak of the sensor. It's heatsoak of the intake tubing, and the sensor is near the walls where airflow is slower. If the IAT sensor was prone to heatsoak then it wouldn't be very reactive to changes in temperature under normal steady-state conditions.
Only other option is to relocate the IAT sensor to the intake manifold.
This particular sensor is not very reactive to temp changes during normal driving. I had an Omega that worked much faster, but accidentally left it with the previous turbo kit I sold. And running an actual MAT sensor would be ideal in most situations, if you did not have any heatsoak issues. If I was concerned enough about this as a real problem, I would relocate the sensor to the airbox area that is sealed off from most underhood heat. As it is, this poor quality sensor is sitting in the intake tube right behind the radiator, which is almost a worst case scenario, but gives me a fine example of how heatsoak affects airmass calculations.
Putting it in the airbox would have the opposite effect. Should be close to the intake valve as possible. The components of the intake tract are still adding heat to the air charge.
In SD some report lean after heatsoak start and others rich. In terms of accuracy...intake valve not up the mast of your radio antenna.
Or play with the bias. That's free and easy.
It isn't a matter of sensor sensitivity... It's a matter of sensor location. Any change to air temperature after the sensor has measured the temp is what the complex temp model accounts for.
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