better driveability after battery change

[Chicobiker]

Hello all.

I changed out my battery today on my 03 OBS (and I also put on my
winter wheels & tires ...) and I noticed a difference in how the car
drives. It seems that the RPMs don't drop as fast as they used to
after I push in the clutch, even when the A/C is on. Therefore, the
shifting seems much more forgiving.

I've read many people talking about the ECU and that resetting it can
sometimes be a solution to many a problem. This implies that the ECU
is adaptable, or learns over time. What is the purpose of this? If a
common suggestion is to reset the ECU, it would appear that the
"learning" feature of the ECU is not necessarily a good feature.

Chico

 

[Carl 1 Lucky Texan]

Hello all.

I changed out my battery today on my 03 OBS (and I also put on my
winter wheels & tires ...) and I noticed a difference in how the car
drives. It seems that the RPMs don't drop as fast as they used to
after I push in the clutch, even when the A/C is on. Therefore, the
shifting seems much more forgiving.

I've read many people talking about the ECU and that resetting it can
sometimes be a solution to many a problem. This implies that the ECU
is adaptable, or learns over time. What is the purpose of this? If a
common suggestion is to reset the ECU, it would appear that the
"learning" feature of the ECU is not necessarily a good feature.

Chico

I wouldn't discount the possibility that the alternator was being
overworked and/or the ground connection was poor.
The purpose of the adaptability of the ECU is, of course, to attempt to
compensate for variations in sensor wear, fuel octane rating, altitude
and temperature. maybe something else I can't think of.

Carl

 

[mulder]

Hello all.

I changed out my battery today on my 03 OBS (and I also put on my
winter wheels & tires ...) and I noticed a difference in how the car
drives. It seems that the RPMs don't drop as fast as they used to
after I push in the clutch, even when the A/C is on. Therefore, the
shifting seems much more forgiving.

I've read many people talking about the ECU and that resetting it can
sometimes be a solution to many a problem. This implies that the ECU
is adaptable, or learns over time. What is the purpose of this? If a
common suggestion is to reset the ECU, it would appear that the
"learning" feature of the ECU is not necessarily a good feature.

Chico

The ECU is continuously doing "adaptive learning" to maintain the
correct air/fuel ratios and timing with minimal knock. It also learns
the values for the idle controller to maintain the proper idle speed.
All cars do this, not just Subaru.
When you disconnect the battery the learned parameters are cleared and
reset to their default values, so the process has to begin all over
again. You may notice the car runs differently for a while until the
ECU has re-learned.
This is a dynamic process, which allows the ECU to compensate for
aging components and changes in the environment (temperature,
barometric pressure etc.).
It is also possible that if your old battery was weak it was placing a
noticeable load on the alternator.

 

[Chicobiker]

It is also possible that if your old battery was weak it was placing a
noticeable load on the alternator.

I'm starting to believe this a little more. The voltage regulation was
not as good with my old battery. When the engine was at idle, the
headlights were a little dimmer than at any other RPM. I could notice
this at stop lights. When I took off again the lights would get
brighter as soon as the RPMs went up. It also happened when simply
reving the engine while stopped. I could even see my dome light
flicker if I had the hazard lights on!

 

[Body Roll]

I wouldn't discount the possibility that the alternator was being
overworked and/or the ground connection was poor.
The purpose of the adaptability of the ECU is, of course, to attempt to
compensate for variations in sensor wear, fuel octane rating, altitude
and temperature. maybe something else I can't think of.

.... the mood of your significant other. If the passenger airbag sensor
detects too much
fidgeting it turns airbag off and reprograms dual zone control to blow
cooler air and turns on seat cooling, er, the latter was Mercedes
option.
My fault.