Project RS

[ScottyB]

cheap mods are the best mods. this will probably interest the 05-06 (maybe 07?) guys who want to Romraider-tune their cars.

the cable for 02-05 cars (aka me) is about $140 and if you're lucky and quick on the draw you can get a used one for about $100. its a cable with a usb connection on one end an an OBDII connector on the other.....as a warm-blooded, opposable-thumbed, soldering-iron equipped simian who is only semi-retarded in nature, i was sure i could do better than drop 100 bones on a stupid cable.

what brought this all on was that i was going to be making a pretty serious roadtrip to Columbus OH in the worst heat wave in recent memory, and the RS still pings like crazy when its really hot out during extended cruises. i'm really not OK with the idea of climbing 5% interstate grades for miles through blacked-out WV (they're still recovering from the huge Derecho storm that hit 2 weeks ago), in 105 degree heat with my wife and some nice luggage, in a car whose engine is detonating the hell out of itself. i need the thing to be rock solid especially at its age. after finding a really helpful thread on NASIOC, i realized i could plug in a much safer engine tune for about $20 through the use of an alternate cable source. turns out this should work for any non-CANBUS (i.e pre-06) subaru, although it looks like 02-03's are still having issues with this.

what we're going to do is use a VW VAG-COM cable and solder some wires to provide the adequete 12v power to the cable so it can do its job. then, we're going to install the right drivers to our laptop so it can see the cable and send it our nice shiny new data. finally, we'll be using an old version of flashing software on the laptop so that the software can't tell that the cable isn't Tactrix brand. sneaky!

first, buy your cable. i used ebay seller Alpha-Bid and got the cable in 3 days from WA. $22 shipped. not bad.
more info obd2


then, find your soldering iron that can barely melt cheese and some wire than has metal on the inside and plastic on the outside. proceed to molest the nice factory solder joints with your junky radioshack iron. you're doing this to connect pins 11 and 16 to jump them and provide 12v power. ace!


finally, download and apply your drivers from FTDI (the producer of the chip in your cable), find an old copy of EcuFlash 1.29a, and go to town. I had to bump my COM port's baud rate down to 4800 so the cable could speak all proper-like with the RS's ECU.

so what was i up to in the first place with all this? i applied a new tune that cut a big chunk of ignition advance off of the low-load section of the ignition advance table so the engine would run smoothly and safely at highway engine speeds and loads. pulling timing is especially important in hot weather when the intake charge is already starting out at like 180 degrees by the time it gets into the combustion chamber. subaru, in its baffling wisdom, decided to just fuck all that nonsense and jack the timing to the stratosphere to probably eek 1 more mpg out of the car on the highway, presumably so they could compete better with their 2WD competition that was getting 30+ mpg. at cruising load the car was sitting at nearly 45 degrees advance. some cars can get away with that, but the EJ25 is an old engine and the head design just can't make use of that kind of timing. the constant pinging pounds the pistons and rod bearings and just isn't very friendly to the engine....at 100k miles i want it to last for another 100k at least, and cutting that abuse out is key.

the result was excellent. no audible knock at any engine speed or load, and power was barely affected on the low end. the ECU now has tons of headroom to pull timing as it pleases whenever it senses knock instead of in the past where it would pull timing all it could but would hit a wall at the factory base timing numbers which were still too high. the car never missed a beat through intense heat (to the point the A/C could barely keep up on high recirc to cool the car) and actually returned my all-time best mpg ever in Ohio at 35.7 mpg over a half tank.

i'll be tweaking the timing further after logging knock feedback over the next few weeks, but this has been a great success so far. Romraider (program to edit tunes) and EcuFlash (program to flash and log tunes) are both free, so i can truthfully say that you can tune your subaru now for less than $25 and an investment of your time in learning the tuning language.