Reset ecu to gain performance?

[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.

[TheToyman75]

Straight from the toyota training docs.

" the "keep alive memory" is cleared by removing power from the BATT terminal. "

I guess you didn't read your own post

Disconnecting the BATTERY not the EFI fuse

[Mos]

Straight from the toyota training docs.

"the "keep alive memory" is cleared by removing power from the BATT terminal. "

I guess you didn't read your own post

Disconnecting the BATTERY not the EFI fuse

In amichie's defence he did not contradict himself. The docs have to be read in context. The BATT terminal is on the ECU itself, and power can be removed from the BATT terminal on the ECU by removing the EFI fuse (in some cars the STOP fuse) or removing the battery clamp off the battery terminal itself. The context clarifies what is meant by "removing power from the BATT terminal" and to infer this means to disconnect the battery is the incorrect context in this case.
One could also argue that you cannot remove power from the BATTERY terminal (as opposed to BATT terminal) itself as one would need to drain the battery.

Mos.

[takai]

In amichie's defence he did not contradict himself. The docs have to be read in context. The BATT terminal is on the ECU itself, and power can be removed from the BATT terminal on the ECU by removing the EFI fuse (in some cars the STOP fuse) or removing the battery clamp off the battery terminal itself. The context clarifies what is meant by "removing power from the BATT terminal" and to infer this means to disconnect the battery is the incorrect context in this case.
One could also argue that you cannot remove power from the BATTERY terminal (as opposed to BATT terminal) itself as one would need to drain the battery.

Mos.

Gee Mos, did you major in Discourse Analysis while you were in Qld, this sounds too much like the DA girls (and a couple of guys) at work....

[amichie]

I was just going to say that MOS. But the thread is going off topic now anyway.

Bottom line is reseeting the ECU will cause the ECU to relearn maps over a few days.


I remember when the first twin cam corolla hatch (AE82 i think) came out they claimed that the ECU would adapt to the driving style of the owner. At the time they claimed 4 acceleration runs at full throttle was enough to put the ECU in a sports mode.

[oldcorollas]

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. "

so... the adaptive memory can hold a RETARDED advance table in memory until cleared??

that seems to indicate that it will reduce timing to protect engine with poor fuel, but it doesn't suggest that the ECU will advance timing to take advantage of better fuel, above and beyond that which is programmed into the base table.... ie, up to factory programmed or more conservative.

ie, if the knock sensor was faulty and didn't recognise knock, then the ECU would advance timing until engine fails.. and this is NOT a situation any manufacturer wants to be in.

is there any indication in the manuals of adjustment of fuel in anything other than closed loop? and if so, what feedback does it have? afaik, no toyotas use wideband sensors (unlike some hondas and VW's at least), so it would have to do something like lean fuel until knock was detected?

hmmm

any reports of this relearning behaviour on non-knock sensor equipped cars?

[TheToyman75]

One could also argue that you cannot remove power from the BATTERY terminal (as opposed to BATT terminal) itself as one would need to drain the battery.

Mos.

One could also Argue that the correct terminology for the Battery Terminal IS what you call the Battery Clamp and the part on the Battery which the Battery Terminal connects to is actually the Battery Post

However I see your point. On that tho, How sure are you that pulling the EFI fuse will clear the ECU memory on all ECU's ? Most have multiple power supplies, some being constant power (For the ECU memory) and also Ignition power. Does the EFI fuse, always disconnect all the constant power to an ECU ?


OC,

Some of the late model Toyota's do have a pretty complex set up with the O2 Sensors. The current model Prado's for example have a pair of heated 4 wire 02 Sensors and a pair of 4 wire Air fuel Ratio Sensors.

I am only aware of learning functionality the removes timing or of course trims fuel. In fact most modern ecu's have both short and long term fuel trim numbers stored for reference.

As fo rthe knock sensor failure - the default is typically that if the knock sensor fails the car goes into a limp mode which may be anything from a simple timing reduction to a completly different program with limited boost, RPM and adjust fuel maps. Even the 1G-GTE goes into a second map for timing if it sees to muck knock and does not clear until you key off and on. An Audi RS6 on the other hand will default to a completely different map which takes all the fun out of owning it and will not reset until forced to do so with an ECU reset.

[oldcorollas]

thanks Rod
i was thinking in terms of more ancient machinery, like 4AG and JZ series, as opposed to the fancy new stuff

[amichie]

You guys should read those manuals. (Autoshop101).

All the answers are in there including how timing is advanced when using better quality fuels both in the short and long term.

[DeftAnesthetik]

my speculation on this "relearning" would be that the ECU is trying to compensate the system for the best fuel economy. i would say if you drove it hard all the time it would adjust for hard driving all the time, unfortunately we dont always drive our cars hard. resetting the ecu will put the system back to "BASE/DEFAULT" and you would see a change in performance (most likely unnoticeable)
I would imagine though that any time the ECU has power it is in LEARN mode, constantly adjusting and revising the default table, for the best fuel economy. so even if you did get noticeable gains in performance by RESETTING. after a while the system is going to level itself out, and you will be back to where you started.

[cooter]

if the ecu takes a few days to relearn your normal driving style (not your agressive one) it could be worth using this trick just for that edge at an event. motorkhana or somethin. then it will go back to being conservative a few days after so you get the better fuel econ again.
just a thought
cheers
craig