Battery disconnected - must ECM be programmed?
01-30-2003, 07:29 PM
#1
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Battery disconnected - must ECM be programmed?
I heard that after the battery has been disconnected, the ECM must be programmed with a scan tool, or driveabilty will suffer. Is this true?
Cheers,
-m
PS: '96 A4 quattro, 2.8L
Cheers,
-m
PS: '96 A4 quattro, 2.8L
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01-31-2003, 05:43 AM
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Yes and no... m
When the ECM/ECU loses power, there are two things that you need to know:
1) A DTC will be thrown indicating that the ECM lost power. This code will be stored and will only be visable using a VAG Tool (i.e., no visable warning lights in the car). This is not a big deal at all and the only reason to want to clear the code is if you are chipped and don't want any evidence that you have been playing around with the ECM.
2) Throttle adaptation should be reset. When your ECM loses power, it must relearn the throttle positions/settings. If you restore power and start driving/revving to quickly, the ECM does not properly learn the positions. So, after restoring power, put the key in the ignition and move to the 'acc' position (power on/engine off) and leave it there for about two minutes (I have found the process takes less than a minute but everyone says two minutes...). You will be able to hear the throttle boddy go through a series of adjustments during this time. After the two minutes you are good to go.
Chris
1) A DTC will be thrown indicating that the ECM lost power. This code will be stored and will only be visable using a VAG Tool (i.e., no visable warning lights in the car). This is not a big deal at all and the only reason to want to clear the code is if you are chipped and don't want any evidence that you have been playing around with the ECM.
2) Throttle adaptation should be reset. When your ECM loses power, it must relearn the throttle positions/settings. If you restore power and start driving/revving to quickly, the ECM does not properly learn the positions. So, after restoring power, put the key in the ignition and move to the 'acc' position (power on/engine off) and leave it there for about two minutes (I have found the process takes less than a minute but everyone says two minutes...). You will be able to hear the throttle boddy go through a series of adjustments during this time. After the two minutes you are good to go.
Chris
01-31-2003, 06:52 AM
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On 96 A4: No problems, b/c we have cable throttle not drive by wire . . .
However, when you disconnect battery, ECM must relearn air/fuel mixture values. Best way to assist the ECM to relearn?: drive on the highway for between 20-30 minutes (avoid stop and go).
But even if you do not do this, the car will adjust to air/fuel mixture, just more slowly.
But even if you do not do this, the car will adjust to air/fuel mixture, just more slowly.
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01-31-2003, 07:22 AM
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This may not be the case...m
I have a 98.5 (pre-dbw) and the throttle adaptation process was always recommended by tuners after restoring power to the ECU. I believe that it is the process that sets the perameters for the actual throttle body positions - and not the link to the gas pedal....<ul><li><a href="https://forums.audiworld.com/a4/msgs/456153.phtml">https://forums.audiworld.com/a4/msgs/456153.phtml</a</li></ul>
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