Dead Battery Question

[Steve Tinker]

As Rick says. Calibrating the DME circumnavigates the learning curve.
Its easy to check - just disconnect the battery for a couple of minutes, reconnect and start the car. You will feel the tickover slightly lumpy and (if you drive it) the performance is not quite as crisp as the engine management system adjusts to fuel octane rating / ambient air temps/ throttle body positioning etc. Leaving the ignition on for the +/- 60 seconds allows the DME to revert back to what it was.
At least that's how I understand it.....

[jsceash]

From what I understand it allows the DME to read and store the cold to warm, value for the MAF sensor heat. throttle body sensor and pedal sensors (0). Reset the learned map to factory value. If the battery goes down slowly to dead or there is a spike these values can be corrupted because they are in volatile memory. Not doing this can mess with the performance for about 30 miles.

I shorted a wire in my relay box and it screwed up my throttle positions to the point that I was going into limp mode and throwing throttle codes. This corrected the problem.

I was told to have all other electrical systems off when doing this. Fan, Temp unit, Radio, lights, doors closed no alarms dinging, etc.