Hi,

I am writing to ask for advice for my parents. They have a 1997 MB C230 and had the battery go dead last week. They replaced the battery, but now it starts and idles, but has NO power and behaves like it has forgotten how to advance the timing. A friend of theirs told them to just drive it around nearby and that it would "figure itself out again over time", kind of like it was coming out of a coma. This seems odd to me, but I dunno much about MB cars and their computer control specifics.

Does this sound reasonable ? On my BMW, an extended period with a dead battery permanently kilt the transmission computer. On their car, it doesn't seem as bad, by any means, but perhaps its a common enough occurance that there is a known workaround or computer reset.

TIA,
Richard

 

Some engine controllers need to "relearn" parameters after the battery has been disconnected for a while. I have another
car that does this. You can drive it around and eventually it will learn everything again. Some cars this takes a while. Some not.
On my car (NOT a Mercedes), there is a trick to making it learn faster. Turn the key all the way to the right but DONT START the car.
So, the ignition is on but the car is not running. Then push down on the gas pedal slowly all the way to the floor and release it
slowly the same way. Do this several times. Maybe three or four times. Then start the car and drive it for a while. This procedure
apparently sets the computer from idle to WOT (wide open throttle) and helps the computer relearn. Who knows if it will help your
particular car, but maybe it will. Or not. Others may find this little trick helpful in the future. Works for me.

 

From the Haynes Service and Repair maunal:
" The engine managment system ECU is of the 'self-learning' type, meaning that as it operates, it adapts to changes in operating conditions, and stores the optimum settings found /this is especially true
for idle settings./ WHEN THE BATTERY IS DISCONNECTED, these 'learned' settings are lost, and the ECU reverts to the base factory settings. When the engine is restarted, it may idle and run roughly until the ECU has 're-learned' the best settings. To further this 'learning' process TAKE THE CAR FOR A ROAD TEST OF AT LEAST 15 MINUTES DURATION, COVERING AS MANY ENGINE SPEEDS AND LOADS AS POSSIBLE, AND CONCETRETING ON THE 2000 TO 4000 RPM RANGE. On completion, let the engine idle for at lest 10 minutes, turning the steering wheel occasionally and switching on high-current- draw equipment such as the heather fan of heated rear window.