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Bull6791

Battery Question

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I have an 05 corolla. A couple of weeks ago I disconnected the battery cables from the battery to clean corrosion from the battery posts and clamps. The cables were disconnected for maybe 20 mim. After I was done I reconnected battery cables.

The first time I drove the car after reconnecting battery I took a short trip to the store.

All the way to the store and home the car had a rough idle. Each time I would stop at a stop sign or red light the car would shake like it was going to stall. All the way to store and home it did this.

When I got home the car was fine.

What caused this: something with the drive by wire or did some thing have to be relearned.

Let me know.

Thanks.

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No worries, perfectly normal.

 

By disconnecting the battery, you erased all the "learned" parameters from the ECM. As you found, by driving it normally, the car will eventually "relearn" your driving style and driving conditions.

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Depends on how you drive and how far off the car's optimal tune is from the baseline tune in the ECM. Usually not more than a couple of days at the most. Most of the time - assuming that the car is in good running condition, those parameters are relearned in a matter of a few minutes of driving.

 

Only time this becomes a problem is when you are forced to disconnect the battery (or clear DTCs), especially immediately prior to smog testing. Aside from the learned parameters, disconnecting the battery will also wipe the I/M readiness monitors for your emissions systems. This can take a fair amount of time to SET those readiness monitors. In some cases, could take weeks of normal driving. If those monitors are not set - you automatically fail smog testing in most states.

 

Worst case I ran into was with my 2002 Corolla - had a reoccurring EVAP codes that needed to be reset on a fairly constant basis. Last time I reset them, took more than a month of driving (~ 2000 miles) to get the I/M monitors to reset to READY. Had to get an emissions testing extension because of it.

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Fish

Ok so every time I disconnect battery ECM has to relearn the perameters

The rough idle I was experiencing was that the ECM relearning perameters.

Thanks

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When you disconnect your battery to either replace it or clean the corrosion from the posts you erase the learned parameters from the ECM.

What I want to know is until the car relearns your driving style and driving condition could you experience rough idle while driving. What other normal things could the car do until it relearns parameters.

Thanks.

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Don't worry - you'll notice any other issues them right away. A lot depends on options on the car. Radio presets will be gone, anything related to the PCM (powertrain control modules), possible alarm issues, etc.

 

Also depends on the owner/operator. Some owners, they don't notice anything amiss with the car. Some find all sort so things wrong with the car. The take home message is eventually, the car will return to normal. Its when it doesn't that you have to start diagnosing things.

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