How tuning works

[race24x]

So I had some questions and was hoping some of the experts could answer them. So how does tuning work? I have had some experience using a Power Commander and other tuners on Snowmobiles, Motorcycles and even my Seadoo. I thought the ECM in the car adjusts fuel and timing using a knock sensor and the O2 sensor. Are the tables adjusted with smaller differences so it has to stay in the variables presented and if so why doesnt it set off a code if it tries to go outside? I would imagine there are some tables being written too, but why for instance wont the stock ECM monitor the O2 sensor and richen it or lean it out without having it tuned and use the block learn to keep moving it up more and more rich or how does it work. Does the table not have enough room to move up? I am just curios as to how it works.

[acammer]

There is an awful lot of information out on the web about this that can give you far more detail than anyone is going to be willing to type out here. There are a lot of things that go into the typical "tune" that a 5th gen Camaro receives. Speed limiters are removed, torque management is modified or removed, transmission shift points/pressures are adjusted, spark timing is modified, knock sensor response is modified, ECT and IAT spark adjustments are modified, MAF response is modified, VE may be modified, target AFR, etc etc. It really depends on why the car needs tuning in the first place.

You are correct that the car when running in closed loop will monitor the O2 sensor and make fueling adjustments accordingly. You're also correct that the ECM only has so much authority to trim those adjustments before it'll run out of room - it will set codes as it approaches the limits of it's adjustment authority. It does the same with spark - it watches the knock sensors to get a feeling on fuel octane content and works between a low and high spark table to lay out the best ignition mapping it can.

It's a broad, broad subject. I suggest you decide what you're most interested in, and start googling and youtubing. Also, the HPTuners forum is a great place to dive deeper into some of the specifics of tuning the Camaro's ECM.

[dreksnot]

Here are just two tables that can be modified; the 1st one is the high octane timing table, the other is a volumetric efficiency (SD) table. And, there are tables that are modifiers of these, and tables that modify the modifier tables. Crazy fun! So, the moral of the story - lots to learn, lots to gain, need lots and lots of time to invest.

[Pro-tuned]

I was wondering who was gonna take a shot at this... if you wanna pick this up it’s a very long road and requires a lot of research and Dyno time even the best are sill learning. I admire your enthusiasm...

[acammer]

Originally Posted by dreksnot

... the other is a volumetric efficiency (SD) table...

And technically this is a complex series of equations in the E38 PCM rather than a simple table. There is software to extract the equations out to a table, and then back to equations after modification. Most will just patch over to an upgraded OS for the ECM with a regular VE table.

[race24x]

Thank you guys I should have jumped out to Google first. In my experience with a Power Commander for instance there is a table at X throttle position and Y Rpms the timing is set to Z. There is no sensor to change that setting. It sounds like this is much more complex that there is a base setting, and then based upon further input from sensors like MAP and knock for instance there are other tables that make adjustments to that setting. I am not a tuner I dont plan on doing anything really with this, I just want to learn more because it is interesting to me.

[acammer]

Originally Posted by race24x

Thank you guys I should have jumped out to Google first. In my experience with a Power Commander for instance there is a table at X throttle position and Y Rpms the timing is set to Z. There is no sensor to change that setting. It sounds like this is much more complex that there is a base setting, and then based upon further input from sensors like MAP and knock for instance there are other tables that make adjustments to that setting. I am not a tuner I dont plan on doing anything really with this, I just want to learn more because it is interesting to me.

It's fascinating stuff! There is a lot of good information out there - just gotta have a good BS filter, because like most things on the internet, there is a percentage of it that's crap.

[race24x]

Acammer Weedsport huh. I was born in Syracuse and used to sneak to the Weedsport raceway (I think) I was pretty young back then. My grandfather owned a bar over in Jordan

[acammer]

Originally Posted by race24x

Acammer Weedsport huh. I was born in Syracuse and used to sneak to the Weedsport raceway (I think) I was pretty young back then. My grandfather owned a bar over in Jordan

Small world. Weedsport speedway is still here. It shut it doors for a few years, and then got some really good financial backing and is now the nicest dirt speedway I've ever seen (and I've been to a lot of the in the north-east). I get over there a few time a year, usually just a bleacher creature, and occasionally helping out in a pit.

Still a good bar in Jordan - it's called Kegs now (maybe it was then too) and they bring in some pretty big country acts a few times a year.

If you're ever passing through make sure you reach out and we can connect!

[JANNETTYRACING]

Originally Posted by race24x

So I had some questions and was hoping some of the experts could answer them. So how does tuning work? I have had some experience using a Power Commander and other tuners on Snowmobiles, Motorcycles and even my Seadoo. I thought the ECM in the car adjusts fuel and timing using a knock sensor and the O2 sensor. Are the tables adjusted with smaller differences so it has to stay in the variables presented and if so why doesnt it set off a code if it tries to go outside? I would imagine there are some tables being written too, but why for instance wont the stock ECM monitor the O2 sensor and richen it or lean it out without having it tuned and use the block learn to keep moving it up more and more rich or how does it work. Does the table not have enough room to move up? I am just curios as to how it works.

There is a huge difference between a power commander piggy back device and actually being able to read and edit the factory calibration.

Piggy backs can only intercept the timing and injector pulse and modify it one way or the other from what the factory computer is commanding.

Piggy backs went out 10-15 years ago in the auto world the Powersports segment has a lot of catching up to do.

It is a whole different world my friend.

[race24x]

Acammer, I sure will if I get down that way. I sometimes travel to Syracuse for work.
Ted, Thank you, I am just curious how it works. I cant help myself sometimes I just want to learn something I will never really use LOL. I appreciate your knowledge. I would love to see the inner workings. I do some SQL programming so in my mind it seems like tables behind an application and the inputs are calculating very quickly to come up with a setting, like asking an application to give you a number based on a whole bunch of numbers millions of times per second. But that is just how I imagine it.

[chef-beavis]

Originally Posted by JANNETTYRACING

There is a huge difference between a power commander piggy back device and actually being able to read and edit the factory calibration.

Piggy backs can only intercept the timing and injector pulse and modify it one way or the other from what the factory computer is commanding.

Piggy backs went out 10-15 years ago in the auto world the Powersports segment has a lot of catching up to do.

It is a whole different world my friend.

Not necessarily. I've been running dual wide-band O2 sensors closed-loop on my tractor since 2007! Daytona Twin-Tec has been around longer than that. HD race tuner and several others are long-time players, too. Not many people still farting with power commanders in my circle.