Power loss after installing new battery
Thread Starter
Junior Member
Joined: Oct 2002
Posts: 33
Likes: 0
From: Nashville
2003 E320 (228k miles) and 2004 SL600 (103k miles)
Power loss after installing new battery
MB roadside assistance replaced my battery, and since then, I've lost power at wide open throttle. When I press the gas to WOT, it seems anemic, and when I release the peddle to 50% of WOT, the power picks up, but not 100%.
Anyone have any ideas? I could disconnect the battery, then reconnect, but should the engine be cold or warm when I do this? I'm guessing a throttle position sensor or something is sticking, and the computer isn't sensing the correct position upon startup.
When MB installed the new battery, the car was cold (65 degrees F) for about a week.
Any ideas?
Thanks, any advice is much appreciated.... Paul
Anyone have any ideas? I could disconnect the battery, then reconnect, but should the engine be cold or warm when I do this? I'm guessing a throttle position sensor or something is sticking, and the computer isn't sensing the correct position upon startup.
When MB installed the new battery, the car was cold (65 degrees F) for about a week.
Any ideas?
Thanks, any advice is much appreciated.... Paul
MBWorld Fanatic!
Joined: Jun 2004
Posts: 1,140
Likes: 2
From: Ashburn, VA
2004 C32, 2006 Honda CBR1000RR, 2007 Harley NightRod, 2013 Harley Road Glide Custom
Just a guess when I say this (I'm no expert). Could the ECU settings been
reset and the car basically needs to learn these settings again? If so, I would
think it should be back to normal within a few hundred miles.
reset and the car basically needs to learn these settings again? If so, I would
think it should be back to normal within a few hundred miles.
Senior Member
Joined: Mar 2003
Posts: 298
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From: LI, New York
87 190E 2.6/1995 M3
adaptive transmission management perhaps... car had adapted to your driving style... battery out reset it to default... gonna have to give it time to learn again... more like P/T 
Newbie
Joined: Dec 2004
Posts: 3
Likes: 0
Hello,
Could be a simple grounding issue.
If the battery terminals were coroded from the old battery, and not cleaned before the new one was installed, you could have this problem.
If the ground is not good on a 12v negative system, your sensors don't report to the computer correctly, as the computer uses the ground as it's base line voltage.
May need to replace the cables.
Cheeper than buying new sensors.
Could be a simple grounding issue.
If the battery terminals were coroded from the old battery, and not cleaned before the new one was installed, you could have this problem.
If the ground is not good on a 12v negative system, your sensors don't report to the computer correctly, as the computer uses the ground as it's base line voltage.
May need to replace the cables.
Cheeper than buying new sensors.
Thread Starter
Junior Member
Joined: Oct 2002
Posts: 33
Likes: 0
From: Nashville
2003 E320 (228k miles) and 2004 SL600 (103k miles)
Much Improved
Thanks for all the great advice. I drove the car for 500 miles, and it appears the car has reprogrammed itself. My only complaint is that it took 500 miles (why not sooner?). Anyway, it's driving great. It's not scientific, it's just a perception, but I noticed two step changes: one at approximately 250 miles and the other at approximately 500 miles.
In regards to the battery cables, I think it's a good troubleshooting step. Maybe my car would have reprogrammed itself much sooner? Since it's driving great, I would rather not risk the chance of disturbing the current setup, so I won't try, but wish I had earlier in the process.
Thanks! .... Paul
In regards to the battery cables, I think it's a good troubleshooting step. Maybe my car would have reprogrammed itself much sooner? Since it's driving great, I would rather not risk the chance of disturbing the current setup, so I won't try, but wish I had earlier in the process.
Thanks! .... Paul
