Reset the ECU?

I recall seeing this posted before, apparently it is considered a service item in Canada? Normally there should be no reason to do a reset and it really doesn't matter since the ECU is constantly learning and adjusting fuel and timing based on 02 and knock sensor inputs. If it is reset it will begin the learning process all over again, but ultimately end up in the same place.

The ECU is reset as it never forgets so if you run low octane or poor quality fuel and the timing is retarded this will always be factored in on the equation. If you run on 95RON timing is retarded but it will never be fully advanced when you go back to higher as the rolling calculations always use the data from running on 'bad' fuel. The reset is performed to allow the engine to reconfigure itself without the history.

I had my sti done as I got caught out and was forced to put regular in it, took it into the dealer and had it reset once i had 98 in it, performace returned to normal!! And the dealer confirmed the above...

R

AFAIK the ECU should eventually get back to where it belongs, however it can take a relatively long time to return to normal after a tank of bad gas and severe knock events. In such a case, if you know that low octane fuel has been run through it, it would be advantageous to do a reset. Otherwise, in normal use and with the proper fuel having been used, there is little or no benefit to be realized from a reset.

I will never get back to the optimum but will get close. Imagine the following

10,10,10,10,10 = Average of 10 10,8,10,10,10 = Average of less than 10. Until you remove the 8 from the running average your average will never be 10 regardless of how many more 10's you add!!

Remeber as your engine wears the ecu is still processing data from the nice new tight engine 24000 miles ago which may not yeild the best results, the reset eliminates the old data that may be irrelevant.

Rossco

True, but close might be good enough if you account for rounding, or if a rolling average is used.

-John O

But i thought that the ECU only saved data from the last 500 miles. If so, a bad tank of gas longer ago than that wouldn't matter.

But. 10,9,11,10,10=10 so you can, in theory, get back to 10

10,10,10,10,10 = Average of 10 10,8,10,10,10 = Average of less than 10. Until you remove the 8 from the running average your average will never be 10 regardless of how many more 10's you add!!

Not if 10 is the maximum

You don't keep adding 10's in a running average! The early ones fall off. In your example, two more 10's and the 8 is gone.

-John O

I didn't see any rules stipulating 10 as the maximum.

I give this thread a 10!