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Old 05-06-2009, 11:43 AM   #1
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Another Dead Battery - Computer Reset Question

Yep, left my Boxster alone for too long and discovered the battery had died. Thanks to this forum I was able to get to the battery and start charging it.

Question: After recharging the battery and getting the car started and running again, I noticed that on full throttle the car surges and slows, while the engine is still revving towards redline. Seems like the computer is retarding the ignition or something. When I go to 3/4 throtle, it starts to pull hard like normal....well, normal for 3/4 throttle.

Is this due to the computer losing some info? Any way I can reset this? Or is this something a shop using OE software has to plug in and program?

The only other issue is a problem with the secondary air injection system...only during cold starts, CEL codes (I lost my OBDC scanner) the ususal O2 sensor error. It could be any part of that circuit though. In the past I've reset the code when the engine is warmed up and noticed no difference in acceleration.

Any help is greatly appreciated.

MD

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Old 05-06-2009, 11:46 AM   #2
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Garage
Could it be bad Spark Plugs/Spark Plug wires?
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Old 05-06-2009, 12:11 PM   #3
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Quote:
Originally Posted by michael_dba
Yep, left my Boxster alone for too long and discovered the battery had died. Thanks to this forum I was able to get to the battery and start charging it.

Question: After recharging the battery and getting the car started and running again, I noticed that on full throttle the car surges and slows, while the engine is still revving towards redline. Seems like the computer is retarding the ignition or something. When I go to 3/4 throtle, it starts to pull hard like normal....well, normal for 3/4 throttle.

Is this due to the computer losing some info? Any way I can reset this? Or is this something a shop using OE software has to plug in and program?

The only other issue is a problem with the secondary air injection system...only during cold starts, CEL codes (I lost my OBDC scanner) the ususal O2 sensor error. It could be any part of that circuit though. In the past I've reset the code when the engine is warmed up and noticed no difference in acceleration.

Any help is greatly appreciated.

MD
When the battery goes dead, or is disconnected, the ECU resets itself and has to "relearn" several things. Drive it for a bit and it should clear up.
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Old 05-06-2009, 01:12 PM   #4
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I've driven the car about 150-200 miles since...not sure if that's enough time/miles to re-learn.

Maybe mines a slow learner?

Is it possible I need to disconnect the battery for a few hours then reconnect to make any changes to the computer? I did recharge the battery while it was connected to the car....

As for spark plugs/wires, I'll have the shop check those when I bring it in. Hopefully this (power surge) won't be the reason to bring it to the shop in the first place.
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Old 05-06-2009, 02:03 PM   #5
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Quote:
Originally Posted by michael_dba
I've driven the car about 150-200 miles since...not sure if that's enough time/miles to re-learn.

Maybe mines a slow learner?

Is it possible I need to disconnect the battery for a few hours then reconnect to make any changes to the computer? I did recharge the battery while it was connected to the car....

As for spark plugs/wires, I'll have the shop check those when I bring it in. Hopefully this (power surge) won't be the reason to bring it to the shop in the first place.
That distance is more than enough; I think at this time you need to do a scan for any active or pending codes and collect a PID catalog (realtime readings of the sensors) to determine where you stand.
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Old 05-07-2009, 04:29 PM   #6
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I guess the moral of the story is don't let your battery go dead!
~M

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