Pacembellum

What makes the factory ecu unable to keep up with additional air flow?

if you dont change the MAF, or intake, and just port the blower and heads, or an x pipe and exhaust, shouldn't it be able to adjust since all that changed is the amount of metered air going past the MAF?

davepl

Yup. And it uses second order predictive functions when it sees the closed loop parameters drift too far.

Since the engine accurately meters the incoming air (MAF) and knows the results of the combustion (O2) I don't know why it's not WAY more accomodating of changes.

I think the biggest problem is the torque tables. The engine knows it's supposed to make (for example) 600 ft-lb at 5000rpm. If it's making 650 it will actually pull timing or even close the throttle to get to the "expected" torque value. So that's part of what a tuner is changing.

Generally, the people who understand it take the attitude of "If it was hard for me to learn, it should be hard for you too". We don't have a competent tuner on the board that really invests any time in explaining things.

Roadrogue

Higgs Boson

then you haven't looked hard enough. I know I have submitted lengthy posts explaining all that. The problem is, no one wants to keep typing it over and over because it is indeed a lot of information, nor is it "hard to learn or teach."

even if you searched User Higgs Boson and a term like say...."trim" you still get 3 pages. "fuel trim" gets you 2 pages. "modification" gets you 3 pages. "tune" gets you 20 pages (lol).

the info is there, the reason the forum keeps all these threads is for future reference....like a modern day library. except everyone wants to reinvent the wheel with a blank page.

I will see if I can find something for you, but really, you guys can search as well. Seems that's actually what's hard to learn and teach.

Higgs Boson

how about post 7? is that helpful?

https://www.corvetteforum.com/forums...-your-z06.html

(dave you even clicked thanks, lol)

Higgs Boson

the simple answer is it can up to a point at part throttle. an ecm bases fueling around a set airflow model that is created around a stock combination. the more you deviate from the temperature and altitude and "airflow combination" the stock airflow model was created around, the less accurate your fueling will become and the less accurate your torque model will become, affecting shifting and other aspects of your drive. yes, you can now change the shift pressure of your automatic transmission by changing how much air goes through your engine.

the most basic aspect of a tune is to get your airflow model to more accurately match the airflow of your new parts combination (among so many other things).

full throttle situations (on a GM V8) have no ability to correct fueling, it runs straight off the stock airflow model so while you will get a limited amount of correction at part throttle, you will not at full throttle, which is a bigger issue and a tune is even more important.

davepl

If there's an active group of hobbyist tuners eagerly sharing information back and forth about the current ECMs in an open forum, it's sure as heck not this forum. And if there is an exception to this rule you're likely it, because you personally do answer a lot of stuff! But even so, as a generalization:

I see a lot of "Do I need a tune" and "Your tune is screwed". But if there are threads with screenshots of HPTuners explaining how to fix anything non-trivial beyond fans, their authors must be on my Ignore list because I sure don't see anything like that.

Maybe Hib Halvorson used to write articles or something, but around here it's too often just guys trying to make each other feel stupid and/or trying to impress by the implication, but not the actual demonstration, of the depth of their knowledge.

And this business of saying "It's not hard because I already know it" is first grade passive aggressive nonsense. I understand lots of complicated things that are easy to me that would be hard for others. I've long believed that if someone can't explain something in simple terms, they do not fully understand it.

Your Post #7 in that thread is a clear counter-point and a great example of what I wish we had more of. Make it annual, not biennial -)

For my personal purposes it's actually the next level of info up... not "what is fuel trim", bur rather "How does the new parametric estimation work and why is it so much better than the old linear". That's the harder stuff. That's the stuff I don't have a good grasp on but that I don't dismiss as "easy".

Anyone who wants the basics should read "Corvette Fuel Injection", with is outdated now but still really good anyway because it's just really well written by a good author. The info is available elsewhere, but he makes it "easy", as you'd say.

All it would take to prove me wrong and shut me up is a really good sticky on the torque model, for example. Or point me at the post that explains it and I'll summarize for a sticky.

Meow, meow. I know how to operate Google. To wit, the word "Idiot" occurs 109 times in your posts.

Higgs Boson

I mean the CF Search function, not google.

and if idiot really happens 109 times in threads I participate in, it doesn't occur in my posts. ;-)

Higgs Boson

https://www.hptuners.com/help/vcm_ed...vanced_e78.htm

davepl

I assume you know, but if you use the prefix:

site:corvetteforum.com

...then you can use Google, the full grammar, and it's a lot more effective search than the search box on the site.

That's hard to know. It occurs 109 times in the threads and 44 times "near" your name. But quotes and replies skew the count as well.

Umm.... sending me offsite for information kinda proves my point about the forum, does it not? But yes, I've read that one in the past, it's decent. It's the kind of thing our members should be writing for stickies! I wrote one for adding an underhood fuse wiring, that was my contribution...

Higgs Boson

Well, I guess that kind of depends on your expectations. This is the Corvette Forum, it's not a E92 tuning forum so I would not expect lots of extensive detail here, I don't come here expecting a one stop solution end all - be all information center.

We could drill down almost infinitely into the code / hex of an ECM but I personally don't think this is the place for it, most people here want to talk about 0-60 times and wax. If you have a hunger for specifics in the ECM, join HPT Forum, you will find many many familiar people there.

I don't look at internet forums as "us against them" communities, that's why there are so many....The ECM in the C7 is used in other cars as well and there will always be more detail when the community is more specialized.

That doesn't take away from the value of Corvette Forum. The topics here are much more diverse and you can hang out here longer than somewhere like HPT Forum where there is basically one topic.

Use each for what they are good at.

davepl

If you're saying "The information is out there but it's not here", then I think you're more or less agreeing with me. But that's OK because I agree with most all of what you said anyway.

I just wish there were folks willing to act as a bridge. For example, I can tell you -exactly- why you cannot format a FAT32 card greater then 32G in a command window. So if someone has a hard question about clusters or sectors or tracks or blocks or bits or bytes, I can answer it to whatever level of detail is required. MFM or RLL? Your call.

But getting "expert information dumbed down" around here on automotive topics is tough. It is literally as though the few people that know the answer disdain those that don't already know. If I ask "Why doee factory ECM have an unused wide band port and how could I make use of that in my own logging", I'm unlikely to get a satisfying answer.

Waxing, chrome vs black wheels, manual vs automatic, C6ZR1 vs C7Z, that's all well covered.

Higgs Boson

That's what links are for!