ECU reset

[Sandals]

Noticed in some other threads about doing ECU resets after minor mods or using higher octane fuel. I am only the 2nd owner of my scoob and the previous owner only ever did around 3k miles a year and since the car was completely standard, I'm questioning whether they used high octane fuel (which I have always used Shell v-power with the occasional momentum 99). 

 

Been doing some googling and some say just disconnect the Battery (negative terminal only?) and press the brake for 30 seconds to deplete all charge. Then I've read that with some imprezas it can only be done via software on a laptop plugged into the car.

 

My car is a 2004 blob WRX, can someone confirm whether the disconnecting the Battery technique would work?

 

Ta :D

[Linx]

I'd also be interested in a definitive answer to this. I'd like to reset the ECU on my Blob but Google searches are contradicting and confusing.

[Gambit]

The Denso ECU’s (Newage) don't have a manual reset function like the JECS ones (classic). The Denso units apparently have a non-volatile RAM, so even disconnecting the battery won't do it. The only way to reset these ECUs is via the OBDII diagnostics port using a computer. Until recently this has only possible at the main dealer or using other commercial solutions e.g. Delta Dash or SECS. So in other words can't really be done without using the OBDII on our cars :( 

[stants]

If you've changed fuel it will 'self learn ' after a hundred miles of so I wouldn't worry too much the bad thing about doing a reset is that it sets all the trims back to zero so knock and afr will be set to factory levels

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[Sandals]

Yeh after various googling I found the same information, from the man Andy F:

 

Ignition timing

This is determined mainly from the MAF sensor and the engine speed. There are maps for high octane and low octane fuels and the ECU selects between them depending on knock sensor activity. The ECU also learns ignition timing from the knock sensor and effectively sculptures these maps over time. Pre 1999 models !Removed! the timing in an area of the map if the knock sensor was ever active. 1999/2000 models will try periodically to advance the ignition again. 2001 and later models run very actively on the knock sensor and adapt very quickly. The practicality of this is that resetting the ECU should be performed on pre 1999 cars if a higher octane fuel is used or if just recovering from a tank of “bad fuel” as sometimes happens. This will enable the ECU to relearn more appropriate ignition timing for the present fuel. It is not worth resetting later models. On 1999/2000 models, typically after twenty or so miles, the ECU has adapted quite a lot. There is no need with any car to excessively load the engine on the brakes or by putting four heavy blokes in the car and driving up long hills. If anything excessive load will only expose the car to more detonation and it will learn more pessimistic ignition timing!

[stants]

Checking mine with the evo scan software it advances it as far as 40 Deg ! Not sure if that right but at idle it goes back to 15 Deg tdc

Knock corrections are only between -2 & +2 so I'm not that bothered

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[Linx]

Great answers. Thanks guys. I have an odb2 cable and laptop . The software I have only reads and clears fault codes. Can anyone recommend a free or cheap program to do the reset? Linx.

[stants]

The free version of ssm2 (subaru select monitor 2 )

It's really good and you can do just about anything with it

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