So Chett tuned my car a few weeks back and I've been trying to come to grips with this whole tuning thang by analysing what he did (compared to my initial map). Its also been interesting getting all the tools working:

  • Tactrix OpenPort 2.0 Cable - connects to your OBDII port
  • ecuflash - opensource software to download and upload your ECU ROM (containing your map(s))
  • romraider - opensource software allowing editing of ROM, plus live logging of parameters as you drive (the logger)
  • airboys spreadsheet - excel spreadsheet put together by some expert which contains a bunch of handy graphs and data manipulation allowing better analysis of your logs and ROM.

As i've been pulling logs I've been uploading them to google drive:

Mods that are currently installed on my car (thanks to Wayne at WHP!):

  • Pyro Performance quad-tipped turboback exhaust
  • Grimmspeed electronic boost control solenoid
  • Perrin Cold-air Intake
  • Innovate MTX-L Wideband AFR Sensor + Gauge
  • Whiteline 24mm Swaybars Front and Rear
  • Walbro fuel pump
  • HKS M35iL Set
  • Cheapo oil catchcan

Now i'm a total n00b when it comes to tuning this car, and there is literally a metric shit-ton of reading and learning before I would even start to consider myself capable of understanding what the hell is going on, so I've tried to keep my life simple by focusing on 2 areas:

  • Boost & Wastegate
  • AFR & Fueling

(the best guide i've found is this one)

So lets start with Boost, maybe because it's the simplest one for me to understand. There are basically 4 tables at play here:

  • Target boost
  • Wastegate Duty Cycle Initial - RPM + Requested Torque -> Initial WGDC
  • Wastegate Duty Cycle Maximum
  • Boost cut - Achieving actual boost above these threshold results in fuel being cut (for engine safety)

Target Boost table simply contains the ideal boost figures the ECU will hunt for. If Actual boost is lower than Target boost, then the ECU must keep the Wastegate closed for longer (to spool up more pressure). In order to determine how long the WG should be closed, a WGDC value is calculated using the WGDC initial value, then transformed via some maths (contained in the Turbo Dynamics tables), and then truncated to a maximum of the WGDC Maximum value.

Effectively the WGDC is a calculated value each ECU cycle of how long the wastegate should remain closed when hunting target boost.

I am pretty sure my Target Boost vs. Actual Boost is off, as I never seem to hit the Target Boost value in the logs that I have pulled since my tune:

Target vs Actual Boost

So although Actual Boost is hitting 0.8 bar which I am perfectly happy with for a safe tune, I am sure that the ECU should at least be achieving Target boost around this level rather than constantly be trying to hunt an impossible Target value. Before Chett did the tune I was able to hit Target boost of slightly higher levels, by simply taking the WGDC tables and adding 20% to each value. This worked well for pull #1, and I hit a solid 1.0 bar of target boost, but on pull #2 I must have WOT'ed at lower RPM and hit the boost cut which killed the fuel (and I literally shat my pants!!!). I was probably way too aggresive with tweaking those values, so I might try it again with much smaller increments to WGDC.

So the questions I need to resolve are:

  • What target boost levels should I be aiming at, and what does a healthy target boost curve look like for my stock engine?
  • What are sane boost cut levels to set?

Once I have answers to the above, it should be fairly easy to tune the WGDC tables to hit the target values above through a bit of trial and error...