Reset ecu to gain performance?

[Z2TT]

I have been reading about people who have taken their battery clamp off for 24 hours so the ECU resets. Then taking it out for a good drive so the ecu "learns" the driving style and "tunes itself" to suit the mods on the car.

I read that it makes a good performance gain.

Is this true?

[MR22ZZ]

Depends on the car.
You can also just take out the ECU fuse for 10-30 seconds for the same result

This is my understanding of it...

Basically what it does is resets the A/F to a base map which is then adapted over the first 50kms or so of driving. So if you reset the ECU and then drive the car hard for a while, it will be well trimmed for the hard driving and most likely produce better power.

The computer will continue to adapt to your current driving style though by averaging out the signals over a period of time anyway though so in some cases no improvement is seen anyway as the ECU has already adapted to the 'best' tune possible for the given factory parameters.

This only works with factory ECUs though obviously.

[parrot]

With bigport 4AGE's it is apparently along the lines of warm up the engine, reset the ECU as above, restart and keep the engine revs over 4000rpm for a given period which I cannot recall.

vague, but someone will know the specifics.

[fixeruperer]

yeh i do it to newer cars when i fit basic mods like exhaust and filter CAI.

[Z2TT]

If stock ECU's can "self tune" themselves to work with your mods, then whats the point of getting after market ECU's that have to be tuned by a tuner?

[MR22ZZ]

The stock ECUs trim the tune to a safe level, where with an aftermarket ECU you can push the limits further.

[JetspeedCamry]

Not to mention the fact that aftermarket ECU 'trims' are from 0-100 and not from 10.2-10.6 (not actual figures just a way of showing its adustability).

[o_man_ra23]

Aftermarket ECU's can also control different mods. Like if you want to remove the troublesome and restrictive AFM or MAF out of your intake line and run of the non intrusive MAP sensor, then a factory ECU cannot adapt to that. Also if you go from a 50mm throttlebody up to a 90mm... it will most likely be way out of the factory ECU's trim range.

And then there are advancements in technology... some times a factory ECU is just crap compared to even the cheapest aftermarket ECU you can buy.

[amichie]

MIne runs better for a few days after an ECU reset and then slowly goes back to factory slug tuning.

[rob_o]

This is a common thing that is talked about on the Soarer forums. They reckon that unplugging the battery for a little while does wonders with the ECU.

[oldcorollas]

do thetoyota ECU's "learn"?

ie, they have a lookup table programmed into the memory, and they have closed loop for O2 feedback (so it trims in cruise mode)...

but closed loop only takes a number of ignition cycles (say, maybe 10-20 ignition events with a 1% step each time...) so maybe 100 ignition events = 50 revs to get into switchin gclosed loop....

but you guys are saying that the trim level from this closed loop is saved as a new lookup table? or the trim is saved as a seperate lookup table?

as for "power" parts of the map, there is NO feedback, except for maybe knock sensor...
how will the ECU learn, and what will it learn?

are you saying that it records the timing advance at which knock occurs, how much it had to back off, and then saves this new advance into memory as the new lookup table?

i wonder how much is true and how much is placebo?

ie, the people proposing they make more power after unplugging ECU.... why would it do that?

[amichie]

are you saying that it records the timing advance at which knock occurs, how much it had to back off, and then saves this new advance into memory as the new lookup table?

Yes it does something like that, its in the toyota training docs on autoshop101.

That is how it makes a slow adjustment for fuel quality.

[Mos]

It does that on engines without a method of setting the ignition timing.
Things with adjustable dissies (like 1G-GTEs) tend to have fixed base timing.

So are people suggesting that by driving the car more aggresively it will trim the tune to be more aggressive?
I've only ever heard of transmission management adjusting to your driving style, but never even a suggestion that this happens with engine management. I suppose it could be possible with engines with electronic throttle bodies, but I doubt anything "old" would do something like that.

[o_man_ra23]

Starting to sound like hocus pocus. Some aftermarket ECUs such as the Adaptronic can learn on power curve.

[Kedderz]

From what I understand of most older toyota ecus from late 80s-90s is the "learning" they do is simply based on closed loop fuel trimming. Any gain I would say would be pure placebo and barely noticeable in the extreme.

[o_man_ra23]

Also, an ECU tunes to an engine, not a driver. It will tune to your engine's mods and condition, not to the weight of your foot (unlike a transmission which will hold gears for longer for you, or shift earlier). Perhaps after a reset it has a faster rate of learning, which is why you get noticeable differences in the first little while after a reset... I would like to see before and after dyno curves to put this to rest though. Anyone got free access to a dyno to prove/disprove this myth?? Mythbuster style y'all!!

[Mos]

With the 1G-FE there were different dyno figures produced on different fuels, but it's in the order of 2 or 3% which could be attributed to other parameters. The larger difference was in fuel economy, which was in the order of 6%.
BTW, it took several fuel tanks to "adjust" to the different fuel. Keep in mind this is a modern engine from the context of engine management. I doubt early 80s management would do as much, and certainly wouldn't do anything tricky with timing to compensate for different fuels.

[amichie]

Straight from the toyota training docs.

"The Effects of Fuel Octane Toyota engines equipped with a knock detection system are very sensitive to fuel octane levels. Motor fuels with low octane ratings will cause the engine to detonate, which will in turn, cause the detonation retard system to retard timing. On some vehicles with advanced ECM operating strategies, an adaptive memory factor is used to track signals from the knock sensor. When detonation occurs frequently, the ECM relearns the basic spark advance curve, retarding spark throughout the entire engine operating range. This retarded spark curve will negatively effect engine performance and fuel economy under all driving conditions, even after a tank of higher octane fuel is purchased. The retarded spark curve will remain stored in the ECM keep alive memory until the engine is operated for a substantial amount of time on the higher octane fuel, or until the "keep alive memory" is cleared by removing power from the BATT terminal. "

[TheToyman75]

All you are acheiving buy resetting the factory ECU is clearing the vehicles short term fuel and timing trims. If you take it for a hard drive after its reset then of course it trims will suit that style of driving. BUT - it will relearn to suit your normal driving style and go back to exactly how it was before you reset it. The triming hear it just that MINOR TRIMING.

Welcome to Ass Dyno's the Placebo effect and the PITA of resetting your clock and radio stations for no real gain.

[amichie]

All you are acheiving buy resetting the factory ECU is clearing the vehicles short term fuel and timing trims. If you take it for a hard drive after its reset then of course it trims will suit that style of driving. BUT - it will relearn to suit your normal driving style and go back to exactly how it was before you reset it. The triming hear it just that MINOR TRIMING.

Welcome to Ass Dyno's the Placebo effect and the PITA of resetting your clock and radio stations for no real gain.

Since when does pulling your ecu fuse reset your clock and radio.

As stated above it seems to take a few days to relearn.