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The mkiv Supra Owners Club

how do i reset the ecu?


redsupraman82

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id like to know this, is it worth doing? if so what will i gain?

 

Yes to clear any old fault codes that may be stored.

 

Note, after resetting the ECU the car may not idle properly and run a bit lumpy to start with, it'll take a few miles of driving for the ECU to relearn the settings.

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Resetting ECU faults was the only thing I could think of. It actually solved my engine problem which was running too lean and misfiring. ECU reset and the things never run better. Was wondering if this was the only problem that could be solved. Seems that it is :)

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  • 4 weeks later...

Remove EFI fuse no1 to reset the ECU and clear stored codes. Removing the battery will do the same but is overkill as you'll lose your radio and clock settings as well. You just need to pull the fuse and put it back, the ECU memory is volatile and is lost the moment it loses power. 5 minutes is daft, 30 minutes is ludicrous :D

 

Resetting the ECU will clear long term fuel trim maps (and ignition trim maps as well). This can cure a problem with overly lean running, it's worked for me once and apparently Noz as well. Resetting the ECU is not a silver bullet though, despite that I've seen it recommended as a 'fix' for all sorts of crazy things.

 

I know the Toyota manuals say how long it takes to relearn, and it's not long. From memory, it's about 30 seconds from starting the engine to get all the closed loops and idle stuff sorted, and about 3 miles of normal driving to sort out the timing. I do know it's nothing like the numbers I've seen bandied about, like 50 miles or an hour of driving :)

 

-Ian

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I know these a fuse somewhere, but i think ajlittler is correct when he said just disconnect the battery for 30 mins.

 

I'm sure there's one somewhere too. Oh, wait!

 

ECU fuse

 

 

Remove EFI fuse no1 to reset the ECU and clear stored codes. Removing the battery will do the same but is overkill as you'll lose your radio and clock settings as well. You just need to pull the fuse and put it back, the ECU memory is volatile and is lost the moment it loses power. 5 minutes is daft, 30 minutes is ludicrous :D

 

Resetting the ECU will clear long term fuel trim maps (and ignition trim maps as well). This can cure a problem with overly lean running, it's worked for me once and apparently Noz as well. Resetting the ECU is not a silver bullet though, despite that I've seen it recommended as a 'fix' for all sorts of crazy things.

 

I know the Toyota manuals say how long it takes to relearn, and it's not long. From memory, it's about 30 seconds from starting the engine to get all the closed loops and idle stuff sorted, and about 3 miles of normal driving to sort out the timing. I do know it's nothing like the numbers I've seen bandied about, like 50 miles or an hour of driving :)

 

-Ian

 

;)

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I know these a fuse somewhere, but i think ajlittler is correct when he said just disconnect the battery for 30 mins.

 

I sometimes despair at the comments posted.

 

Obviously ajlittlers experience vastly overshadows that of ianc who has been a tech mod (and supra guru) for the past x number of years!

 

.

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I really can't see that resetting the ECU is going to cure much, the only thing's retained would be idle fuel trims and closed loop fuel trim, as for timing it would only be the default knock map, if you think about it the ONLY way the ECU gets any feedback about fueling is how it adjusts fuel trim to remain stoic at idle and closed loop via the lambda sensor voltage, and timing through the feedback from the knock sensors.

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