Here is the strategy I tune with. Everyone does it different, but what is important is you find things that provide you with consistent, yet safe, results.
So, let us assume we are doing a simple stage two tune.
- Setup - First Flash -
- Remove all CL/OL delays as needed.
- Set all TA/DA maps to 6.5 to 7.0 degrees from 1.30 load on to max load.
- Set all base timing maps to one map and remove TA + 2.0 degrees from the same load points.
- Set WGDC tables to 0
- First, Boost -
- Query the ECU for Atmospheric pressure, manifold pressure, FBKC, FLKC, RPM, Engine Load, Engine RPM and LC-1
- Do a pull in fourth gear to redline watching AFRs and knock
- Graph the boost for the car in the log using manifold pressure - atmospheric with engine RPM to find where you natural boost curve is and what your spring pressure is. I do this for two reasons, one I want to see what the turbo does with no help and I also what to see what effect the exhaust system has on spool. For example, one of my 07 STIs has a EVO 2 and another has a full 3". One requires considerably less WGDC in order to achieve the same target boost.
- Take the information and start throwing WGDC at the car and see how it responds. I set all my maps the same and give my max WGDC 5% more on any given RPM on 95% throttle.
- Dial in the WGDC until your high gear is maintaining the boost levels that you are requesting.
- From here, log pulls in the first, second and third. Graph these and see what WGDC is need on the MAX WGDC map is needed to hit target boost or close to it in the those gears.
- Once boost is done, move onto fuel.
- Second, Fuel -
- Using the information from your boost map look at your AFRs and take note of what RPM and load the boost is coming on. I usually will choose around 2-4 psi depending on the turbo.
- This is where people differ in style. I choose to keep a 12:1 - 12.5:1 around spool area and gradually fade to 11.1:1 - 11.5:1 AFRs at redline. Figure out what works best for you and your gas.
- Looking at your log, choose the AFRs from the wideband that are withing .10 - .15 of each other. Then using the target AFR, let's say 11.1:1, take that value and divide it to get your scaler. Using 11.1 with a current AFR of 10.5:1 we get a value of 1.057. So, take the load ranges and RPM and multiply by that value.
- Now, you should notice that the afrs can dance around up to a whole AFR point. That's OK. Just roll with it and dial it in.
- Once you have that done, scroll over the maps and look for stupid stuff. For instance, let's say you are running 11.0 around the map, and there is a point where it is 11.5 and then back to 11.0 for whatever reason. Even it out. Some may feel this, other may not. I prefer to find a consistent value that gives me the acceptable ranges.
- Do a couple pulls and look for knock and graph your boost and AFRs on the same graph. Try to fade rich while boost is start to move but keep a little lean while spooling.
- Third, Timing -
- After boost and AFRs are dialed in, go in for timing. You want to KC, timing and knock with load and engine RPMs. From here do a couple of pulls in high gears to get a decent load.
- I usually add in half the timing I pulled at the start and see how the car reacts. Slowly add timing in and again look for timing jumps that can cause knock with heavy jumps. For example, 10 degress to 25 degrees.
- Once you find a happy balance between timing use ECU edit to interpolate things a little bit and call it done.
- I usually leave timing conservative until I can get the car on the dyno.
- Last, Loose Ends -
- Before I am done, I like to just 'drive' the car. Watch how it behaves and the different load ranges the driver goes through.
- Watch the AFRs to make sure you do not need some fine tuning based on the way the person drives. Watch for knock. Cruise on the freeway to ensure that there is no cruise knock.
- Get money.
Phew! I just spilled that out and I know I am missing some things. Just go slow and things will work out just fine.
Don't worry about things like AVCS and whatnot until you feel comfortable with the basics.