Originally Posted By: rationull
Originally Posted By: gathermewool
You're absolutely right, but this is my wife's vehicle, in which she had driven maybe 100 miles since the reflash. I'm not sure if this enough to set all parameters in the ECM, but her having driven the vehicle prior to me hopping in and driving around is different than my experience might have been had I driven it directly after the reflash.
Yeah, sorry I wasn't actually trying to imply that the reset was the only cause of the changes. Just came to mind because I'd been surprised in the past by how different mine drove after a battery disconnect. I would've thought 100 miles would be enough although I think some parameters can also take a certain number of hot/cold drive cycles to set correctly.
You're absolutely right, and I replied to clarify. I didn't take your post as anything other than inquisitive, since "how long after the reflash" is a pretty key piece of information when describing changes.
Originally Posted By: dgunay
Originally Posted By: gathermewool
Originally Posted By: dgunay
Originally Posted By: gathermewool
I'll have more time to really explore the change when we drive 2+ hrs to visit family next weekend, but I had some time to drive it yesterday (about an hour total of mostly highway driving) and here's what I think so far:
1. Startup: since the update, the startup cat-lightoff behavior seems different. By this, I mean that it used to stumble and run a little rough until the secondary air injection pumps turned off, and then things would smooth out. now, it's smooth and remains smooth through the whole process.
2. Acceleration: acceleration seems to be smoother, with a little more linear throttle response. Before the update, throttle response was a little too punchy, with instant 4-5# of boost and a surge forward at tip-in, unless you very gently depress the accelerator. Now, the same level of throttle will produce a pound of boost or so.
3. Power: Seems, so far, to be unchanged. Again, it's much less punchy, but, with a little more application of throttle, it seems to pull about the same.
4. Other Changes: Boost control seems a little more refined. Aside from the above-mentioned effects, acceleration seems to occur at a more appropriate RPM. Before the update, RPM wouldn't vary a ton, with boost building when more power was needed. Now, RPM seems a little higher, with lower boost, for the same load. I don't hear as much turbo spool noise, but that's not a bad thing.
Boost doesn't seem to spike as much, remaining relatively steady once max boost is achieved. I don't accelerate at max boost often, so I'll have to spend some more time feeling out the change.
I bet they re-tuned the STFT.
I'm not sure I know what that means. STFT, or short-term fuel trim, is the ECM adding or subtracting fuel based on the O2 sensor input, as compared to the MAF sensor. STFT is a live correction, whereas LTFT is more of a semi-permanent correction, based on long-term STFT trends.
That's why now you have a smoother ride. The more STFT gets close to 0%, the smoother ride you'd have (when it's in closed loop indeed).
The car needs to run 300+ miles to get LTFT properly adjusted.
I don't think so. Fuel trim is simply based on the difference between what the ECM should be and what is, applied as a correction factor, based solely on sensor input (in this case, the O2 sensor, compared to the MAF sensor.)
BASE fueling tables might have been changed, but I'd put my money on the following:
1. Throttle mapping: change the requested torque tables for throttle positions, so that response is more linear.
2. WGDC: Just like aftermarket offerings, Subaru has taken what it knows from driver and test mule feedback and adjust waste-gate duty cycle tables to more smoothly control boost, and limit over-boost conditions.
3. Other: I'm sure timing adjustments, boost and, as previously alluded to, fueling, were all fine-tuned.
What I'd be curious to know, is whether Subaru does more than fix a problem when they do these types of updates. What I mean, is do they apply a fix AND add some refinement, based on empirical data? In this case, did they not only fix the pre-ignition and rough idle issue, but also apply other fixes to make the overall tune better, too?
Originally Posted By: Virtus_Probi
Just picked up my car...got the old plugs back and they definitely look well used, but I am not sure what they are supposed to look like with that mileage. I did notice upon close inspection that one had a chip in its insulator, but I'm going to be a nice guy and assume that happened during the removal process.
The leakdown test results...
Cyl 1 - 3 PSI
Cyl 2 - 2 PSI
Cyl 3 - 2 PSI
Cyl 4 - 3 PSI
The drive back to work was short, I will drive it more tonight and see how it feels. Guess it will take a while for the ECU to "learn" the car with its new program, anyway.
Please report back. I'm curious to hear what you think.