Noobie to tuning. I'm a programmer though, awkard.

[beigmatt]

Hi there all,

I am looking around the website trying to read as much as I can about tuning but am only finding bits and pieces of information I am having trouble putting it all together.

I am the proud owner of a 2005 Chevy Equinox. It has a 60degree 3.4L V6 engine, which brought me here. It has a Weapon-R intake and pipe with a custom heat shield around the filter, along with a resonator delete.

I am a computer programmer/website developer and have learned a ton about cars the past couple years. I'm really interested in learning alot more about OBDII, PCM's, ECU's and how to make the most out of modifying it.

I saw an OBDII to USB cable I can purchase on amazon. There were programs that enable me to reflash the computer, edit fuel maps, etc. I am really interested in how I may be able to tune the computer, or reflash a fuel map profile designed for increased horsepower, or better gas mileage.

Please excuse my ignorance, but I'm all ears. I am very familiar/comfortable with my car, the power it outputs and its shift points (based on how i've been driving it lately). I'm very excited to see what modifications I can make. I'm really hoping someone can help point me the right direction and make all this make sense.

Thanks.

[caffeine]

I think HPTuners supports your PCM, but its expensive at around $5-600 for the software and cable.

I don't think an OBD-II - USB cable will do you much good.

There aren't any inexpensive tuning solutions unless you considered swapping an older PCM from a different car. I'm not sure how much the BCM in your car is integrated with the PCM, but it may make a PCM swap problematic to get it to function properly.

[caffeine]

Looks like HPTuners only supports 07-09 equinoxes. You might be able to upgrade to that PCM with less headache than a downgrade though.

[SappySE107]

I wouldn't do it. Get another car that has better support. Something with an LS1 would be ideal if you really wanna do OBD2. If you just want to tune, run away from OBD2 and get OBD1 if you want to learn the programming behind the tuning. Get megasquirt if you just want to tune. Id rather use a carb and distributor than OBD2.

[Z26-T]

I wouldn't do it. Get another car that has better support.

x2. It's not like tuning a honda civic or a Camaro that has tons of aftermarket available to it. If hptuners doesn't support it or DHP won't work I wouldn't try any harder unless you want to go to a stand alone controller like a megasquirt. You will run into issues with your theft deterrent system since it is integrated into the BCM.

[beigmatt]

Thanks for the posts everybody. Unfortunately this car is my daily driver and I will be driving it for several years to come.

Here's a thought that I am hoping you guys can figure out. The air intake I installed is great and I have it surrounded by a heat shield for colder air intake. How much increase in performance/MPG does this allow? Does the MAS recognize the readings properly? Will a tune enable you to take more advantage of an intake then you would just by adding it on?

[ForcedFirebird]

If you understand binary, you can use that cable to crack the code using winols and tunerpro since it's not supported, but it's not for the faint of heart.

[beigmatt]

So from what I understand I am able to tune, but it's harder to do it with OBDII on my car because of limited support. I can downgrade my computer to something compatible with my engine, which will be easier to modify.

I am still light years behind you guys. Even when it comes time to tune, what paramaters are ACTUALLY being modified after a tune that allows for the change in performance?
Shift points? More proper intake/exhaust calculations? Fuel mappings? Camshaft or fuel timing?

Thanks all for making this less complicated.

[armos]

I know this is about 4.5 months old, but maybe the OP has email notification.
I first started trying to learn ECM tuning a couple years ago, and it definitely has a steep learning curve. It took a long time to get where I felt like I knew what I was doing.

So from what I understand I am able to tune, but it's harder to do it with OBDII on my car because of limited support. I can downgrade my computer to something compatible with my engine, which will be easier to modify.

My (limited) experience with tuning is really just on OBD-1 era GMs. Recently, I took a quick look into tuning a late 90s OBD-2 Cavalier. I gave up that idea when I saw what a morass of BS the OBD-2 world is. Not much is openly documented, everything is a secret and costs a ton of money. It seems to be nothing like the ease and accessibility of tuning an OBD-1 car, unfortunately.
That said, downgrading your ECM would seem like a pretty rash thing to do, unless you have a really good reason. For a daily driver, probably not a good idea to get too crazy with it. Besides, you'd be starting from scratch if you did that, which is really not realistic for someone who doesn't have prior experience. It's a lot easier to learn by making small changes to a stock tune. Essentially, you start with the "Hello World" app.

I am still light years behind you guys. Even when it comes time to tune, what paramaters are ACTUALLY being modified after a tune that allows for the change in performance?
Shift points? More proper intake/exhaust calculations? Fuel mappings? Camshaft or fuel timing?

Thanks all for making this less complicated.

In terms of performance, you're not likely to gain much unless there have been significant mechanical modifications. The factory tune is already well matched to the factory build. When people make major modifications that's when the factory tune gets increasingly problematic.

On cars that use a MAP sensor, and not a MAF, a major component of tuning is to adjust the Volumetric Efficiency table. This table tells the ECM how efficiently it should expect the engine to burn fuel at different combinations of RPM and manifold air pressure. This table serves a major role in calculating how long to open the injectors.
I assume pretty much every modern car uses a MAF sensor. I don't know much about tuning MAF systems, but they are adjusted differently than what I described above. I get the impression they aren't as sensitive to being dialed in just right.

The upstream O2 sensor allows the ECM to automatically compensate the fueling values to some extent, but that doesn't work perfectly. I don't know how much better it is on a modern system, but I know at least on a 1980s OBD-1 car, the learning behavior has major limitations which make it far from ideal, and not a good crutch to rely on.
Even on modern cars, the factory has a different tune binary for pretty much every possible combination of drivetrain options. That right there shows that automatic learning isn't as adaptive as people sometimes assume.
If there's some reason that the factory fuel programming isn't accurate, it's better to retune it rather than relying on the learning behavior.

Datalogging, and preferably a wideband O2 sensor, are needed to observe whether the tune appears to be running rich or lean under different conditions. Then you adjust the tune accordingly.

I don't have a computer controlled transmission but I assume shift points could be modded, yes. You'd need to be careful with that stuff because if it's programmed wrong it could cause slipping and hurt the trans.

Another common adjustment would be ignition timing.

Depending on how well the code has been reverse engineered, you can enable/disable various features. Some examples: security, check engine codes, "lean cruise" highway mode (some old ECMs supported this but had it disabled due to EPA)

There's personal preference adjustments people sometimes make. I've adjusted the conditions when the lockup TCC will engage on my car. You can usually adjust temperature thresholds for the radiator fan. People sometimes change idling parameters - on mine I got rid of the excessive fast idling when cold.

It can turn into a hobby. My car is essentially stock but I still play with it. Making small changes to a stock car is a good way to learn IMO. If a car is heavily modified, tuning becomes more complicated and much more necessary.

The ability to datalog can be valuable when diagnosing problems with the car.

When I was learning this stuff, I found a lot of useful discussion and some long articles on thirdgen.org. That's an OBD-1 site, but if you dig into the old articles you might find it interesting. This site is good also but not as frequently posted upon. There's also gearhead-efi, and I read a lot of old threads (like 10yrs old) from diy-efi - they came up a lot in web searches.
There might be detailed articles out there for OBD-2 systems, I don't know as I've never worked with it. But the basic principles shouldn't be much different, and OBD-1 cars are simpler so they might be easier to learn. Unfortunately it might be a challenge to get any kind of tuning access to your newer car.

Just poking around in TunerPro can be interesting. To do anything useful that program also requires an .xdf definition file and a binary for some vehicle. Binaries take some digging. I think they sometimes get posted on gearhead-efi and I remember downloading some from an old diy-efi archive. The .xdf tells it how to interpret the binary, so it needs to match or the data will be garbage.
Again though I have to point out, TunerPro is an OBD-1 thing. I don't know what the OBD-2 guys use.