When purchasing my WRX, one of the things I was very excited about was that it came with a Cobb AccessPORT the previous owner purchased. For the non-Subaru people out there, this nifty little device plugs into your car and allows different fuel, ignition, and boost maps to be loaded onto the car. On a bone stock WRX, flashing a new Stage 1 map will net you aproximately 25 horsepower and 28 ft/lbs of torque. Not too shabby for the little gadget. If you install a full turbo-back exhaust or a different turbo, the maps can be tailored to your car and power numbers can be even better. Finally, there are maps provided by Cobb for fuel economy and valet mode (low boost and RPM limited).
The car already had a Stage 1 (unmodified car) map on it, so I would eventually be interested in a Stage 2 map when I do the exhaust. Short term, I wanted to simply test out the fuel economy map and possibly the valet mode for fun. I got the data cord this past weekend so I could connect the AccessPORT to my computer and load the updated maps onto it. Once connected, however, I ran into a problem. I downloaded the correct 2004 maps for my car, but the AP was saying it was for a 2005 with an automatic transmission. Because of that, I wasn’t able to load my 2004 maps. Even when I tried using the AP software to change what ECU it recognized, it would still think it was for a 2005 AT.
Off I went to my various Subaru forums. After doing a lot of digging through threads, many over five years old, I found out Cobb released an update to the first generation AccessPORTs. They realized the maps for a 2004 WRX differed slightly from a 2005 WRX and released a software update for people to fix this issue. I’m not sure if the previous owner unknowingly did this update, or if he simply received it with the 2005 update already on it. Cobb later had to release another update to revert 2005 APs back to the 2004 version since they used the same hardware in the AP. Because this issue was only for the AccessPORT v1’s and the current v2 AccessPORT has been out for several years, tracking down the updates became quite a chore.
After doing more searching, I found the document Cobb released about the issue as well as the ReprogramAP_04WRX software needed to correct my AP issue. Even after posting a thread on Cobb’s technical forums, I didn’t receive much help. Their reply was they no longer supported the APv1, but would gladly give me a $200 credit for a APv2 if I sent them my old one. I don’t blame them since they want to make money, but I don’t currently need a v2. Because it was so difficult for me to find these documents, I decided I would put them out on the web as well for those looking to do the anti-update to their v1 AccessPORTs. The whole process takes about 45 minutes to an hour to perform.
Note: While this procedure worked for my AccessPORT, I do not make any guarantees it will work for yours. I read through the directions several times and followed them exactly. Doing this procedure wrong can fry your ECU. Be very careful.
- Unmarry your AccessPORT from your car. Be sure to follow Cobb’s instructions on how to verify your AP is in an unmarried state. Failure to do this can brick your ECU.
- Connect your AccessPORT to your computer. Because it is unmarried, you’ll have to press the up and down arrows at the same time to connect.
- Run the ReprogramAP_04WRX utility to revert your AP to 2004 mode.
- Be sure to download the newest Cobb Map Manager software from Cobb’s website.
- Before loading any maps in Map Manager, select your ECU by clicking on “AccessPORT“, then “Change ECU Identifier“. You may need to physically remove the ECU cover found under the passenger footwell to verify the correct ECU numbers.
- Load the current maps onto your AccessPORT.
- Remarry your AccessPORT to your 2004 WRX following the instructions in the AP user manual.
- Cobb’s Instructions: MY04_WRX_update (the links are outdated)
- ReprogramAP_04WRX Utility: ReprogramAP_04WRX.zip
After doing this, I was able to load the correct 2004 WRX maps onto the AP and put them on my car. I found with the new map on my car, I gained a lot more low-end power. My car bogged down quite a bit when taking off from stops, but the new map took care of that. Mid-range power was also improved. My car seems to run much smoother and, hopefully, will get better mileage now that I have the correct map version on my car. Hopefully, this comes in handy for anyone else having the same problem as me. Just remember to follow the instructions EXACTLY. Good luck.