Mr.Atlantis Posted July 9, 2014 Share Posted July 9, 2014 Since I purhased my '08 Legacy Outback, I've noticed that everytime I unplug my battery (usually pull the ground, while leaving the positive attached) my car wants to stall everytime I let off the gas with the clutch in thereafter. This will persist for about 100 miles or about 5 - 6 start-up cycles and then everything seems to smooth out. Is my computer being flashed every time I unplug my battery and forcing ECU to re-learn every time? This can't be normal if so. Is a car similar to a computer whereby it has some kind of CMOS battery in order to store stuff when battery is unplugged? Any advice would be nice. It's very hard to identify whether I fixed anything if I continually have to deal with this problem every time I unplug the battery. Link to comment Share on other sites More sharing options...
ocei77 Posted July 9, 2014 Share Posted July 9, 2014 It does not have a cmos type battery. The computer is starting from zero and has to learn everything each time. If you wish you can get one of those units that plug into the lighter and keeps a small charge in the system. O. Link to comment Share on other sites More sharing options...
Mr.Atlantis Posted July 9, 2014 Author Share Posted July 9, 2014 I saw those at the store but I thought that was more for radio settings and such. Oddly though, this does not happen to my buddy who has an '08 Impreza. He can unplug his battery and his car drives exactly the same after plugging it back in. Link to comment Share on other sites More sharing options...
1 Lucky Texan Posted July 9, 2014 Share Posted July 9, 2014 it may very well be that your car has a problem that the ECU is 'barely' able to correct. Such that, when trying to run on the ECU's default map, which assumes all positive factors, it exhibits poor running. Then, after a few drive cycles, the ECU has made ,perhaps drastic, changes to ignition timing and A:F ratios to get reasonable performance. Getting freezeframe data or using FreeSSM or some other deeper scan technique to look at fuel trims and similar data would be a good next step I think. Link to comment Share on other sites More sharing options...
Mr.Atlantis Posted July 9, 2014 Author Share Posted July 9, 2014 it may very well be that your car has a problem that the ECU is 'barely' able to correct. Such that, when trying to run on the ECU's default map, which assumes all positive factors, it exhibits poor running. Then, after a few drive cycles, the ECU has made ,perhaps drastic, changes to ignition timing and A:F ratios to get reasonable performance. Getting freezeframe data or using FreeSSM or some other deeper scan technique to look at fuel trims and similar data would be a good next step I think. Makes sense... Basically, my car may have underlying issues that are being corrected to the point that I don't even notice them. If this is the case - is it something that the dealership could scan for me? The same friend with the Impreza has a pretty good scan tool with a Windows CE GUI - I'll see if it's capable. His scan toold is called: "The Determinator" believe it or not. Silly name, but works pretty well and does quite a bit. Link to comment Share on other sites More sharing options...
1 Lucky Texan Posted July 9, 2014 Share Posted July 9, 2014 yeah, from what I've read, some of those apps can get more helpful data than just DTCs. Give it a shot! Link to comment Share on other sites More sharing options...
Caboobaroo Posted July 10, 2014 Share Posted July 10, 2014 Anytime the ECU power is disconnected or the ECU memory cleared, the ECU has to learn from square one. Since 2005, they've been using a drive by wire system and the ECU has to relearn where the stepper motor needs to sit at idle. Here's what I do... After disconnection or cleared, turn key on, wait for gauges to sweep, don't start the car, shut key off and remove from ignition. Do this three of four times and give yourself 30 seconds between each time to key off to key on. Start car and don't touch the throttle. Let it idle for 20 minutes and take it for a drive. During test drive, pull over, shut it off, pull key out, wait 30 seconds, key on, gauges sweep, start car. Might have to do that 2 or 3 times. Link to comment Share on other sites More sharing options...
Mr.Atlantis Posted July 10, 2014 Author Share Posted July 10, 2014 Anytime the ECU power is disconnected or the ECU memory cleared, the ECU has to learn from square one. Since 2005, they've been using a drive by wire system and the ECU has to relearn where the stepper motor needs to sit at idle. Here's what I do... After disconnection or cleared, turn key on, wait for gauges to sweep, don't start the car, shut key off and remove from ignition. Do this three of four times and give yourself 30 seconds between each time to key off to key on. Start car and don't touch the throttle. Let it idle for 20 minutes and take it for a drive. During test drive, pull over, shut it off, pull key out, wait 30 seconds, key on, gauges sweep, start car. Might have to do that 2 or 3 times. Yeah, that may speed up the process to at least the same day. My car is running normal now anyway though. Basically with my driving habits - the ECU seems to re-learn in about 2-3 days. Link to comment Share on other sites More sharing options...
Mr.Atlantis Posted July 11, 2014 Author Share Posted July 11, 2014 yeah, from what I've read, some of those apps can get more helpful data than just DTCs. Give it a shot! Will do, thanks again. Link to comment Share on other sites More sharing options...
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