GC8 ECU reset and fast re-learn.
Taken off another subaru site, but sounds like it will work good. I will try it tomorrow.
Classic (GC8 - JECS) ECU Reset
1.Ensure engine is at normal operating temperature, turn engine off
2.Locate the two ECU connectors, located under the steering column and consist of a black plastic male and female connector, and a green male female connector.
3.With the ignition OFF connect black to black and green to green.
4.Turn on ignition, do not start the engine, depress the accelerator pedal to full throttle, then return it to the half-throttle position and hold for a few seconds, and then release
(Engine Check lamp turns on).
5.Start engine and then drive for at least one minute, keeping road speed above 11 Km/h.
At this point the check engine light should start to flash the all clear signal (steady 1/2 second interval flashes). If the check engine light does not flash, or indicates some other sequence, there is a fault present in the system.
6.Stop the car and turn off the engine.
7.Disconnect the black and green connectors.
8.Job complete - ECU is now re-set.
This has been shown to accelerate the factory ECU’s ignition timing learning process. This procedure is commonly known as the Vishnu Reset after the company, Vishnu Performance, that wrote this on a Subaru forum.
Background
There is something called Ignition Advance Multiplier (IAM) as part of the OEM ECU software. It represents, by some complicated algorithm, the average learned positive knock correction applied to the ignition maps. It’s represented in 1/8th degrees increments. 1 being the lowest and 16 being the highest (1/8 to 2 degrees in absolute terms).
The “happier” (knock free) the car is, the higher the number will be. Conversely, the lower it is, the more knock prone it is.
This number, after an ECU reset or ECU swap defaults to 8 and usually creeps up to 16 (if well mapped, over a week to re-learn) through normal driving. Depending on driving characteristics, this can happen within a few hours or a few weeks. Well, here’s a way to make it happen in about 5 seconds ….
Fast learning procedure (GC8 WRX)
1.With the car fully warmed up, reset the ECU.
2. Drive to a nice open road without traffic. Don’t go on boost until you get there. Put the car into gear (3rd gear works the best) bring the revs up to 2600rpm.
3. Push the accelerator pedal down slightly so boost stays around 2–4psi (~0.2 bar). You will need to MAINTAIN 2500rpm and 2–5psi for approx 5 seconds (You can do this by left-foot braking gently as to prevent acceleration).
During these few seconds, the advance multiplier (which you can’t see, so you’ll have to trust me) will go from 8, to 12 and then to 16. Works like a charm. And on your reset ECU, it is worth an immediate 10–20 BHP.
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