Clearing of Adaptation

audibum

Well-Known Member
Re: Clearing of Adaptation

Racebred said:
Is it a good idea to clear all your adaptation (meaning timing, MAF, knock sensor.. the whole works) each time you do a mod? I know most of us never do that, but let's say we change to a CAI, or change exhaust, or headers, or cams, or decat, dont you think it should be SOP to clear your adaptation?

comments?

yes, i totally agree. we should clear all values regularly and not only when we mod tho.

i do it every fortnight on my palm....always feels like a brand new car...

how do bimmers do it?
 
currently the scantool palm software that we have access to doesnt have the clearing of adaptaions function. Only for clearing of fault codes. For the former, we have to go to places like riverview, bvo and juzz who have the tools to do it.

why would you clear your adaptation if you have not done any mods? wouldnt the engine be running "wrong" during the time between the clear and when it fully adapts?
 
very little actually adapts in one of these cars - fuel injection, ignition timing, shift pattern, and in the case of BMW perhaps cam phasing. Shift pattern changes rapidly to match driver torque request so there's really nothing to reset there. Short term fuel trim moves fast, long term a little slower, but still quite fast - I put it at as little as warmed-up 10km (or less) to reach fresh adaptation. ignition timing retards really fast when necessary, and creeps back to as programmed moderately quick. I would imagine cam phase adaptation being about as fast as ignition timing because it influences knock.

Clearing adaptation feels good only because it speeds the return to normal values whether or not the conditions allow for it to be done reliably. If temps are not back down, octane not back up, etc. Then the car is going to return to previous compromised condition and along the way run on the knock limit or perhaps a little over - which is not good. So I would not reset it unless I know conditions have improved. As for mods - depending on what type of mods are being done, I would clear adaptation, but only before looking at what OBD is saying. Like if you're running a +10% fuel trim and you're installing a mod that is expected to increase airflow and the base map is not changed, then it would NOT be good to reset.

Piggybacks are a different matter. It is best to tune a piggyback off a reset ECU so you know the state of tune is based off a reset ECU. If you base it off an ECU that has adaptation values, the next time the ECU gets reset, the values may be far from what is required. Ignition timing and open loop AFR critical because there is no feedback loop.
 
Shaun said:
very little actually adapts in one of these cars - fuel injection, ignition timing, shift pattern, and in the case of BMW perhaps cam phasing. Shift pattern changes rapidly to match driver torque request so there's really nothing to reset there. Short term fuel trim moves fast, long term a little slower, but still quite fast - I put it at as little as warmed-up 10km (or less) to reach fresh adaptation. ignition timing retards really fast when necessary, and creeps back to as programmed moderately quick. I would imagine cam phase adaptation being about as fast as ignition timing because it influences knock.

Clearing adaptation feels good only because it speeds the return to normal values whether or not the conditions allow for it to be done reliably. If temps are not back down, octane not back up, etc. Then the car is going to return to previous compromised condition and along the way run on the knock limit or perhaps a little over - which is not good. So I would not reset it unless I know conditions have improved. As for mods - depending on what type of mods are being done, I would clear adaptation, but only before looking at what OBD is saying. Like if you're running a +10% fuel trim and you're installing a mod that is expected to increase airflow and the base map is not changed, then it would NOT be good to reset.

Piggybacks are a different matter. It is best to tune a piggyback off a reset ECU so you know the state of tune is based off a reset ECU. If you base it off an ECU that has adaptation values, the next time the ECU gets reset, the values may be far from what is required. Ignition timing and open loop AFR critical because there is no feedback loop.

woohoo, tks shaun for that info...gonna take me a few days to digest all that haha..

how's life in US?
 
hi leonard. It is excellent in many ways (experiences, learning, new friends, new industry contacts), poorer in a few ways (food, old friends, family, asian culture) - necessary compromises in order to get on with life and build a good foundation for the future.


The earlier post was typed in a hurry early this morning local time (morning blurness) so I have to make some important clarification...

earlier post has punctuation error. It should be "...octane not back up, etc. - then the car is..."

Also, technically the knock sensor is a feedback loop for ignition timing but what I meant is that it is more like a on/off switch for retard rather than a constant correction based on knock sensor voltage. Yes there is a range in which varying degrees of retard are applied but it is quite narrow and subject to much interference, plus you don't want to be operating inside that range anyway. Also you could be 50 degrees or 1 degree from the threshold and the knock sensors would not know.

closed loop AFR is constantly correcting but is also somewhat on/off with the limited range narrowband, but at least it knows when it is close to target. also, conditions for knock are alot more dynamic than AFR. so AFR - at least in stock or lightly modified cars - is a lot more stable.

In stock cars, ignition timing is the primary means to controlling limited knock because it can be changed the quickest. So it comes way over AFR and cam phase, or boost changes to deal with knock. In fact ign timing is so overwhelmingly the largest and easiest factor to change that I should not have mentioned any other factor (including variable cam phasing/lift) as a means of knock control because they all come in at a distant second (boost control being the slowest - which is why you won't see your A4 pull boost to control knock). However a situation in which variable cam phasing/lift would be used is to maintain optimum ign timing to maintain efficiency even under non-transient knock (eg. full tank of low octane gas). The engine can be knocking, but by limiting inducted mass, compression is reduced yet optimum ign angle is maintained. Better than retarding ignition and raising EGT, better than reducing/closing throttle on a system that has one and suffering pumping losses. Needlessly sending a car to limp mode may also be held off. This would be another benefit of the new throttleless BMW systems if the engineers chose to map it. Conventionall throttle-bodied engines (both drive by wire and drive by cable) without this degree of cam control are incapable of doing this.
 
As for your 10km reaching fresh adaptation thing, I've tested on my E46 MS43 ECU and it takes just a little longer than that. Probably a day. These days ECUs learn fast. But as for 10km, the LTFT has barely moved 0.5% from 0.

You're right about shifting values downwards (closer to 0) when your LTFT is already say >10% and you're increasing airflow. Thus it takes time (again, less than a day only) to let the value return to 10%, and then some more, to adapt to the airflow mod.

So does it mean that if we increase the airflow, we do not reset the adaptation? Meaning if you're already on 10%, it'll take only a day to reach your desired %, say, 14%? meaning there's no need to reset in any case?

So, the qn remains, to reset or not to reset?

On the qn of piggyback, you say that it's better to clear your adaptation and do your tuning from 0%. Does that mean that after the piggyback tuning is completed, your LTFT should permanently stay at 0% so that there'll not be double correction like you mentioned?
 
Shaun said:
hi leonard. It is excellent in many ways (experiences, learning, new friends, new industry contacts), poorer in a few ways (food, old friends, family, asian culture) - necessary compromises in order to get on with life and build a good foundation for the future.


The earlier post was typed in a hurry early this morning local time (morning blurness) so I have to make some important clarification...

earlier post has punctuation error. It should be "...octane not back up, etc. - then the car is..."

Also, technically the knock sensor is a feedback loop for ignition timing but what I meant is that it is more like a on/off switch for retard rather than a constant correction based on knock sensor voltage. Yes there is a range in which varying degrees of retard are applied but it is quite narrow and subject to much interference, plus you don't want to be operating inside that range anyway. Also you could be 50 degrees or 1 degree from the threshold and the knock sensors would not know.

closed loop AFR is constantly correcting but is also somewhat on/off with the limited range narrowband, but at least it knows when it is close to target. also, conditions for knock are alot more dynamic than AFR. so AFR - at least in stock or lightly modified cars - is a lot more stable.

In stock cars, ignition timing is the primary means to controlling limited knock because it can be changed the quickest. So it comes way over AFR and cam phase, or boost changes to deal with knock. In fact ign timing is so overwhelmingly the largest and easiest factor to change that I should not have mentioned any other factor (including variable cam phasing/lift) as a means of knock control because they all come in at a distant second (boost control being the slowest - which is why you won't see your A4 pull boost to control knock). However a situation in which variable cam phasing/lift would be used is to maintain optimum ign timing to maintain efficiency even under non-transient knock (eg. full tank of low octane gas). The engine can be knocking, but by limiting inducted mass, compression is reduced yet optimum ign angle is maintained. Better than retarding ignition and raising EGT, better than reducing/closing throttle on a system that has one and suffering pumping losses. Needlessly sending a car to limp mode may also be held off. This would be another benefit of the new throttleless BMW systems if the engineers chose to map it. Conventionall throttle-bodied engines (both drive by wire and drive by cable) without this degree of cam control are incapable of doing this.

tks shaun, that post will take a week just to understand the acronyms..haha

good luck in US, when u back?
 
Racebred said:
As for your 10km reaching fresh adaptation thing, I've tested on my E46 MS43 ECU and it takes just a little longer than that. Probably a day. These days ECUs learn fast. But as for 10km, the LTFT has barely moved 0.5% from 0.

The problem is not so much distance as it is the loads the car sees within that distance. If the car was fully warmed up like I specified in the earlier post, and thenfull range of driving conditions (higher loads short of open loop) was carried out in 10km or less, I am sure the adaptation would take place. It is to the engine's detriment for repeatedly seen large fuel trims not to be applied long term / multiplicative. In 10km it is easy to explore the right loads in closed loop 10, 20, 30 times if you so wish to. Now, what car is going to ignore a +10% fuel trim after seeing 30 out of 30 times within 10km?

So does it mean that if we increase the airflow, we do not reset the adaptation? Meaning if you're already on 10%, it'll take only a day to reach your desired %, say, 14%? meaning there's no need to reset in any case?

Yes, I see no point in resetting if you know you're going to be returning to the same point and beyond.

So, the qn remains, to reset or not to reset?

Assuming you are now at 10% - if you know you're going to end up closer to 0% (meaning 5 or less), reset. If you know you're going to be closer (but still under [meaning 5-10]) 10%, do not reset. If you know you're going to be above 10%, do not reset.

On the qn of piggyback, you say that it's better to clear your adaptation and do your tuning from 0%. Does that mean that after the piggyback tuning is completed, your LTFT should permanently stay at 0% so that there'll not be double correction like you mentioned?

Yes. If the tuner is not attempting to change the target closed loop AFR, and uses the piggyback to augment/diminish injector pulsewidth to give the O2S exactly what it wants to see, then it'll hold 0% for a while. However, as the mass, pressure, and exhaust sensors, as well as fuel system components wear, the stock ECU will have to apply a correction of its own. This should be pretty small... though stacked up worn tolerances can add up to quite a bit. The good thing is stacked tolerances are not a problem for people like you who take care of their car and not neglect them - checking on its condition regularly.
 
oh yah.. another minor one is throttle body adaptation, but unlike AFR and ign timing, it is close to totally unrelated to mods for power
 
hmm going by your paragraph, what you say is that you'd expect LTFT to remain close to 0% if you clear your adaptation before going for a piggyback?

if yes, then periodically checking your LTFT will be a good way to dismiss any claims of piggybacks slowly getting "neutralised" by your ECUs, right?
 
Racebred said:
hmm going by your paragraph, what you say is that you'd expect LTFT to remain close to 0% if you clear your adaptation before going for a piggyback?

Only if the tuner did not try to use the piggyback to change the closed loop AFR. If he/she (and oh what a she if the tuner IS a she!) tried to change the closed loop AFR without blinding O2S or scaling the voltages off the O2S, then the stock ECU will start correcting. Scaling is better than blinding because it is not as easily detected by the stock ECU O2S test cycle that is run ever so often to detect faulty O2S.

if yes, then periodically checking your LTFT will be a good way to dismiss any claims of piggybacks slowly getting "neutralised" by your ECUs, right?

Yes, up to a point. You can force a fuelling change beyond what the stock ECU can adapt to and shift the AFR curve around at will (to a limited degree) with the methods mentioned before in the old Delphi threads on piggybacks. Is the maxing out method is used, then fuel trim will be pegged to either end of the scale depending which way you've gone.

The problem with maxing out fuel trim is that when the ECU gets reset, things get thrown off a lot and the car has to adapt back to it.
 
thanks dude. I think for piggyback so far only obit has closed loop tuning. and even then i believe we can opt to choose whether we want to touch closed loop values or not. so thats not a problem.

hahah i cannot remember the old delphi threads on this topic, during the clarence days... coz i didnt understand any of these shit then.
 
This conversation is too cheem. Can explain in lay man terms?

:screwedu:
 
Racebred said:
thanks dude. I think for piggyback so far only obit has closed loop tuning.

Yeah so it is claimed. I haven't seen its workings or heard any explanation as to how it defeats the ECU searching for malfunctioning O2S hence hold permanent AFR tune state.

and even then i believe we can opt to choose whether we want to touch closed loop values or not. so thats not a problem.

Yah.. to tune closed loop AFR you put in a disproportionate amount of effort for the gains you get. Not really worth it unless you like the challange, or if you are in racing class which limits tuning options and you need that last tenth in response and/or power. Never heard of such a class.

hahah i cannot remember the old delphi threads on this topic, during the clarence days... coz i didnt understand any of these shit then.

Hahha no lah I wasn't referring to the threads from wayyy back in the Clarence days. The recent one was perhaps 5-8 months ago. The one that had Greg participating on it as well.
 
SMYUEN said:
This conversation is too cheem. Can explain in lay man terms?
:screwedu:

A series of specific probing questions is diifficult to answer in simple terms.

If I asked you about the options one has in directing the evolution of a gene, following up to the answer with other questions, there would be no choice but for you to get specific. RB and some others have been discussing piggybacks for a while now and for whatever reason, desire to truly comprehend it. To those who do not wish to understand, this whole thread is useless and should be ignored. There is no info too simple, no info too cheem - only info that is not for use by specific individuals at a specific point in time.

The layman explanation and advice has been repeated thounsands of times before and is everywhere you look. Try searching. If you somehow can't find it.. then here it is... "Piggybacks are good for increasing a stock NA engine's performance by some 3-8%. Leave all tuning and understanding to your friendly tuner."
 
Man.... :screwedu:

I dont even think my car understands adaptation. Am lucky it doenst have carbs already.......

Shaun: You are right, horses for courses and in this case, both me and my car are on the wrong course.... :errr:
 
Hi Leslie, what are you driving now?
 
1987 328 GTS. Am pretty sure that most of the acronyms that you and Shawn were using are redundant. Only one applicable with this car in my book is PGPSTM....


Please God, Please Start This Morning.... :laughlik:
 

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