Within the next month I'm going to get my ride (2005 STi) tuned. Not sure if I wanna stick with my Cobb AP version 1 or just get an open source tune. Currently without a tune, I'm putting down 289 hp / 305 lbs torque to the wheels according to a dyno run at TopSpeed. My main question is which type of tune will squeeze out the most mpg. And also, should I wait for spring, summer, or just do it now while the weather is still a little chilly?
Ask your tuner which he prefers. I don't think one is going to give you better MPG than the other. I guess with the AP, you can create different maps that you can switch so one is a high MPG map and the other would be your high boost map.
There aren't any actual "running" differences between OS and V1 AP. There are a few tables that we have access to with OS that we don't on the AP. The AP V2 gives the launch control and flat-shifting, but the V1 really doesn't give anything that the end-user will notice. HOWEVER, the V1 does allow your tuner to do real-time tuning. That will save some time and let your tune be very precise. It also lets you change maps if you want to without having to have a laptop in the car. If you've already got the AP, I'd suggest keeping it. Siegel
The V1 still has the same real-time tuning, it just has a limited amount of "memory" in the base/reflash map. The more changes made from stock, the more memory gets used up. So with a V1, if you make a lot of changes you might have to run a Base Map and a Realtime Map. The V2 has "unlimited memory" for base/reflash, so any map can be Base Map or Realtime Map. Siegel
I agree, with the above, but as for mpg, there is no great secret on it. Main determination of that is the accelerator pedal. As long as you keep it out of boost you will get much better mpg.
out of curiosity, since this is about mpg, can you adjust he target stoic for closed loop (which is what you use most of the time when cruising) and try for a bit leaner AF ratio? in either AP or OS. i used to have a CRX and what i did was bump the timing a bit. it would not pass inspection though so i had to retard it a bit before testing.
Yes you can...in both I believe, but would have to check the various year ECUs to make sure. There are just some tables in Cobb that we don't have access to.
the tune has EVERYTHING to do with MPG. Get a tuner that can tune worth a crap and the mgp will get better. Precisely a tuner that knows how to calibrate the MAF curves.
if you have to pay to play if you want a mpg car there are other options if you like an optimized car go talk to a few tuners and make your decision Anyone can make it run high mpg but do you really want to run the risk of running too lean ? Do you want to pump tires up and run a skinny wheel to get 40 mpg ? or take out all the seats and door panels to get a few more mpg?
your mpg actually will be determined by a number of factors. Scott Siegel tuned my car back in may of 07' 06 sti Turbo XS tmic, Perrin 3" intake, DP, Prodrive Exhaust 3"-4"tip, and Cobb accessport, he extracted about 420crank/460crank torque at 18.3psi. I haven't added a thing in 3 years but the mpg changes depending on load/season/fuel provider/and where i am driving more so then any other element. Stock city average was 19mpg/hwy23 that was my stock readings. tuned in 07 this is the whole year average city-20.7/hwy24.9 08'-city-20.3/hwy 23.2 09'-city-21.1/hwy 23.7 10' so far gas mileage has been crappy this year for some weird reason city 19.9/hwy 22.8 I get the best mpg from april-oct here in Washington, from Nov-March the gas is really crappy because of how cold it gets here, that and I am running studs- amazing traction, very loud and not ideal for cruising above 65mph. I never use cruise control to many hills. One thing to point out I imagine I could hypethetically get better mpg all around if I took about 30lbs of things out of my trunk, however the items I have in there have actually helped myself and other drivers throughout the last 3 years while driving through Snoqualmine Pass. Survival Box in the back Rope 70' First aid kit/big bag Water 2 camel backs 20lbs of tools Lastly How you drive will determine how well or poor you mpg will be. I rally offroad in this car, I do the speed limit and rarely ever use the AC. I only get fuel at Shell or chevron- thats what scott told me to put in it and nothing else goes in this car ever, other then maybe race gas once in a while.