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MY05 STi (2Ltr) with Link G3 and lots of mods - tuning history.


Ben Prendergast
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Hey All, Thought I'd start a post here on my tuning progress, I'm at the point where I've tuned my fuel/timing maps as far as I can without a dyno, so thats next. Its the STi Ej20 so has a relatively strong bottom end. Mods: Intake: Hyperflow FMIC with CAI and Catch can, AVO silicone inlet Turbo: Gtpumps GTPS03 (TD06Sl2 core with 20G and 8cm housing) Exhaust: AVO dump pipe in Fujitsubo catback, Gtspec headers/uppipe heat coated and wrapped Fuel system: 800cc injectors, Fuel Reg, split fuel rails ECU: Link G3, Techedge WB02 sensor, Knocklink, and AVCR I'm running about 11.2AFRs at redline and 14.7 in vacuum/0psi, and about 23 degs timing advance at redline Shooting for 1.3kg/cm (18.5psi) and 1.45 (20.5psi) for special occasions :) Using Shell 100RON fuel. Just setting up a fast street car, maybe a few 1/4 runs and a track day here or there. So thats about it, can anyone chime in with some advice on the following? 1. Whats the best way to tune warm up enrichment? Should I still be shooting for AFRs in the 14.7s? If so I've had to pull a heap of fuel from the stock maps as the car just bogged like crazy when it was cold (even though I'm babying it). 2. Does anyone have any advice on tuning timing on the road? I'm not seeing any knock, but I don't really want to tune with the knocklink, rather maybe looking at MAF output or something? 3. Closed loop fuel, I've got it set to 5% and gain control on 3, at idle it seems to swing between 4 and -4 but a higher gain just makes it swing more dramatically. Is that normal? 3. Any general road tuning tips?? I've just been logging a heap of data, no load slow revs up the tacho, brake-loading to keep the cells occupied for a second, and cruising. Thanks for any help!

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  1. A factory car will pretty muchly run 14.7 all the time during idle/cruise at warmup.  Mainly this is for emissions, but thats what you should be tuning for.  The base maps never promised to be perfectly tuned so yeah, you will have to tune the warmup.  Make sure your IAT correction is set up properly also.  In warmer dryer climates you will need less enrichment for warmup.  It will takes weeks of cold starts and cold engine running before you get it just right...
  2. Use a knock listening device and headphones like a KnockBlock.  That is what most dyno tuners use.  The idea is not to run more timing until det occurs, but just enough to give you as much power as it will make.  Unfortunately on most turbo engines, they will keep making power until det occurs!
  3. Higher gain = faster response, so it will try harder to correct the fuel.  Because there is always delays in a closed loop system, higher gains means it will over correct and eventually oscillate.  It is supposed to oscillate around 14.7:1, that is the idea, but slowly and only a little amount of oscillation.   Remember it is a trim, so you must have your mixtures as close as possible with CLL turned off.  Run a gain of about 1.5 to 2. and up to about 10-15% trim.

  4. Sounds like you have it under control...  but get yourself a knock listening device!

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