car computer question...

[tooter]

Does anyone know how long you need to leave the battery disconnected for the computer to completely forget the old information so it can relearn new engine performance parameters from installing aftermarket parts?

[CTScott]

It is basically just long enough for the capacitors in the ECM to drain down, which takes a couple of minutes. You only reset the short term fuel trim when doing this.

[tooter]

Thanks for the info CT...
I thought it might not take long for a reboot but then wasn't sure when someone said they were going to leave it disconnected overnight. I'm focused more on economy than performance and so want to be sure to get the benefit of any alterations.

I have another computer question if you don't mind. If I do some flux welding on the exhaust system, are there any precautions necessary to protect the car's electronics?

[CTScott]

Originally Posted by tooter

Thanks for the info CT...
I thought it might not take long for a reboot but then wasn't sure when someone said they were going to leave it disconnected overnight. I'm focused more on economy than performance and so want to be sure to get the benefit of any alterations.

I have another computer question if you don't mind. If I do some flux welding on the exhaust system, are there any precautions necessary to protect the car's electronics?

I asked the some thing to buddy of mine who's an auto body guy. He said that his shop always disconnects the battery and alternator and if it is accessible, they pull the ECM connector(s) when welding on a car.

Typically the ECM and the alternator's voltage regulator are the two devices most susceptible to the voltage spikes that may be induced when welding.

There are also surge suppressors that can be purchased that connect across the battery terminals that eliminate the need to disconnect anything.

I have welded a couple of times on Crashy, where I didn't think to disconnect the battery or ECM and didn't have any issues.

[tooter]

I did some reading on the welding issue and it's like cures for the hiccups.

However, locating the clamp did seem to be important. I flux welded an exhaust tip by clamping the engine side of the pipe close to the welding site without disconnecting anything and it worked just fine.