#2003 WRX ECU FLASHING HOW TO#
#2003 WRX ECU FLASHING SERIAL NUMBERS#
#2003 WRX ECU FLASHING DRIVER#

#2003 WRX ECU FLASHING HOW TO#

I will not go into detail on how to preform everything step by step. This modification can not only make the car preform better and feel more responsive, but also can theoretically increase the reliability of the engine over the stock ECU tune due to eliminating detonation from running a lean AFR. Correcting this by editing the stock ECU ROM to force open loop fueling mode results in increased timing and an increase in engine power as a side effect of eliminating detonation. This is why you may notice that the car feels more powerful after an ECU reset or battery disconnect. Since the knock is not caused by timing and is due to a fueling issue, the ECU continues to pull more timing each time it sees a knock event resulting in dramatic reduction in performance. In my car, this actually caused detonation (knock) which the ECU attempts to correct by pulling ignition timing. In most cases this is due to the stock ECU tune holding closed loop fueling mode for too long. It was nice to see the car go into what I believe is flash mode.Many owners of second generation Subaru Impreza WRXs have noticed poor throttle response or a 'lumpy bogging' feeling in the low-mid rev range. What we need is for somone to read their settings from an open port 1.2 and upload them. If you look at the 1.2 schematic there are inversion bubbles on the transmit side of the TXD and DTR# comparators. I noticed the configuration file seems to have the TXD and DTR# lines inverted. After this change I still wasn't able to successfully read the ecu however, ecu explorer now says 'Preamble 1 error' rather than 'preamble 1 no response' After uploading the configuration the car now goes into proper flash mode!!! The CEL flashes once and the fans don't cycle for 5-6 seconds waiting for a connection. I uploaded that cable configuration to mine and tried it. I found someone on openecu who had offloaded a 1.3U cable configuration.

#2003 WRX ECU FLASHING SERIAL NUMBERS#

It turns out the FTDI has internal EEPROM memory for holding cable serial numbers as well as other interface parameters. I downloaded a programmer for the FTDI chip it'self called MProg 3.5. I modified my Vag-Com to have these connections. The Vag-Com is missing a connection from pin 7 to pin 3(L line) and from pin 15 to pin 9(K line) as shown in the open port 1.2 schematic. The Vag-Com cable's ground pin's 4 & 5 appear to be the same as the open port 1.2 schematic.

I have modified my adapter to run the battery voltage directly to pin 11 bringing it high all the time(Maybe a bad idea but it hasn't fried anything yet). In the Open Port 1.2 schematic this line is connected to the battery voltage through a regulator chip and modulated by the RTS# serial line. I'm not sure why the 04's flash without this. This line is said to be Subaru specific and needs to be brought high during flashing.

The Vag-Com interface lacks a connection to the VPP line (Pin 11) on the J1962 OBDII connector. The Vag-Com interface is most like an open port 1.2 cable and uses LM339M Comparators to electically isolate the car from the rs232. I took the Vag-Com cable apart and started drawing out a circuit schematic. When the key is turned to the on position the car enters test mode (fans/relays cycling) but never gives the check engine light flash and waits for a connection as proper cable does(no fans cycling). The odd thing I noticed about this cable is that it never puts the car in flash mode.

#2003 WRX ECU FLASHING DRIVER#

I have tried about every combo of driver and flash software possible with no luck. It seems anyone attempting to flash an 02-03 with the vag-com cable gets the same results. EcuFlash 1.29a - says 'There was an error check the log' Ecuexplorer - says 'Preamble 1 no response' then shuts down the read. Using every combination of driver(FTDI/Tactrix) and flash software I've found:

Flash block installed with +12VDC straight from the battery. Ebay Vag-Com, Blue, alpha-bid(ebay seller name) style 2002 WRX USDM (Tried the combo on a 04 wrx and it worked first time) Lets pool knowledge in here and figure this out. I've played with this cable quite a bit lately and I think we can make this work for the 2002/2003's.

2003 wrx ecu flashing