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View Full Version : Attention: Disconnecting battery DOES not clear the ECU adaptation values


Mr Paddle.Shift
08-31-2003, 03:22 AM
This is a confirmation from a master tech I know who worked for the BMW dealership for about 10 years. I spoke to him about the "disconnect battery and leave for 10mins" trick. He confirms with me that that is only for pre-1993 BMWs, not for our E46s anymore.

In order to clear the ECU adaptation values, you have to approach the dealer and hook up your car to the MoDIC.

If you somehow "feel" the difference with the battery trick, that is more likely to be psychological. I had the values cleared the right way and trust me, the car feels totally different.

So spread the truth!:thumbup:

Nick325xiT 5spd
08-31-2003, 07:14 AM
Honestly, I have a hard time believing that something that gets updated constantly would be stored in non-volatile RAM. Given the limited lifespan of these sorts of chips, it really just doesn't make sense. With all due respect to the master tech, I'd like to know from someone who actually either designed, or at least has the knowledge to repair the circuit itself. (And we all know that no dealership tech will repair the boards themselves.)

Mr Paddle.Shift
08-31-2003, 10:30 AM
You're right about that volatile RAM data as well, Nick. Remember that our ECU is capable of storing top speed and highest REV? All those are erased as well.
But remember there is possibly both long term and and short term adpatation values. I have been bought into the battery trick as well. See, how many steering wheels have I changed in the past year and how many times do I have to disconnect the battery to work on the electronics. Even during the ownership of the S/C, I have to fine tune the AFR to get the right mixture. Each time, the batter trick is used. This time round, after getting the tech to physically clear the values, the car felt different.

That being said, there is a set of procedures to properly clear the values. Not just a hook up and clear. Raf saw it so he can support me on that. The battery trick has definitely become an urban legend for the E46s. Though there is no harm getting the reset done through the OBD II port physically.

EDIT:

I just found some interesting info on the TIS. When the DME unit has cleared the stored values, the engine could lead to an erratic idling and disturbed over-running after starting. This happens for a while til the new input values are adapted into the DME. I seriously don't recall that actually happened with the battery trick, but it did happen yesterday with the MoDIC hook up. The engine revved up on its own for a while before settling down. Again Raffi can affirm that as well. :angel:

Raffi
08-31-2003, 11:48 AM
Raf saw it so he can support me on that.

....

Again Raffi can affirm that as well.

Yes and yes on both counts.

Nick325xiT 5spd
08-31-2003, 07:16 PM
The possibility of long and short term adaptation values is certainly an interesting one, and a rather convincing argument as well. I still remain convinced that the gas pedal maps are altered by the battery/key trick, but I would certainly accept the possibility that there are further levels of adaptation. I *really* wish I could find a copy of the "M52 Info Sheet," which detailed a guy's experience with his '95 325is, and included a pre and post-battery trick dyno.

joema
08-31-2003, 08:01 PM
I know this will be controversial, but here goes: yesterday at a lecture I asked Steve Dinan himself do current non-M3 e46s have any adaptive throttle behavior and if so how does that interact with his engine software. I asked him twice to be clear he understood the question.

He said (standing in front of a projected fuel injection map with a pointer in his hand) there's absolutely no adaptive throttle behavior in current non-M3 e46s, and that it's an urban myth that there is. However he said there are adaptive aspects to the ECU software, but not from a driver/throttle standpoint. For example upon starting, the throttle body butterfly quickly drives to full open then close, while the potentiometer generates a curve of that action. Data from that is used to calculate the current linearity of the throttle mechanism, which adapts for mechanical and electrical aging. It's an automatic calibration sequence.

There are also adaptive aspects based on knock/ping detection, ignition timing adaptation, ambient temperature, water temp, etc. He stressed how current sensors and ECUs are so powerful this can have a major difference in perceived (and measured) power. E.g. a dyno run with the hood open vs closed can cause significant power differences. He showed charts illustrating ignition timing being significantly retarded as engine tempeature increased from low normal to high normal (not outside normal). But these are short-term adaptations based on environment and current engine condition, not long term "learning" adaptations based on driver behavior.

IOW a consequence of modern ECU/sensor suites wringing max power from the engine is they also reduce that power to preserve safety margins as engine temp, ambient temp, water temp, etc. increases. This goes far beyond (and is much quicker acting than) pure physical effects such as less dense intake charge because of underhood heat.

It doesn't take a 100F day pulling a trailer to cause this, either. E.g. you could do one full throttle acceleration, and that could reduce power 5% for subsequent runs, barring a significant cooldown period. The ECU monitors the sensor suite and retards timing, richens mixture, alters valve timing, whatever it takes to preserve themodynamic safety margins, hence engine longevity. Unfortunately most of these result in temporarily reduced power. Worse, to enthusiasts intimately aware of their car's behavior, the perception that throttle response is always changing -- one day quick and crisp, another day somewhat sluggish and mushy.

If what Dinan said is correct, my own theory is much of what is attributed to an "adaptive throttle matrix" is actually varying engine behavior based on changing ambient conditions and engine demands. In a sense there is short-term adaptation based on driver input; more throttle equals more power, resulting in more heat, resulting in retarded timing, etc. But it's not the longer-term "learning adaptation" commonly discussed.

There apparently is adaptive transmission shifting, but that's different than the throttle. My question (and Dinan's answer) was specific to the e46. Maybe other BMW cars like like the new e65 valvetronic do have some kind of learning throttle behavior. For better or worse I wanted to share what he said.

pdz
08-31-2003, 08:36 PM
I know this will be controversial, but here goes: yesterday at a lecture I asked Steve Dinan himself do current non-M3 e46s have any adaptive throttle behavior and if so how does that interact with his engine software. I asked him twice to be clear he understood the question.

He said (standing in front of a projected fuel injection map with a pointer in his hand) there's absolutely no adaptive throttle behavior in current non-M3 e46s, and that it's an urban myth that there is. However he said there are adaptive aspects to the ECU software, but not from a driver/throttle standpoint. For example upon starting, the throttle body butterfly quickly drives to full open then close, while the potentiometer generates a curve of that action. Data from that is used to calculate the current linearity of the throttle mechanism, which adapts for mechanical and electrical aging. It's an automatic calibration sequence.

There are also adaptive aspects based on knock/ping detection, ignition timing adaptation, ambient temperature, water temp, etc. He stressed how current sensors and ECUs are so powerful this can have a major difference in perceived (and measured) power. E.g. a dyno run with the hood open vs closed can cause significant power differences. He showed charts illustrating ignition timing being significantly retarded as engine tempeature increased from low normal to high normal (not outside normal). But these are short-term adaptations based on environment and current engine condition, not long term "learning" adaptations based on driver behavior.

IOW a consequence of modern ECU/sensor suites wringing max power from the engine is they also reduce that power to preserve safety margins as engine temp, ambient temp, water temp, etc. increases. This goes far beyond (and is much quicker acting than) pure physical effects such as less dense intake charge because of underhood heat.

It doesn't take a 100F day pulling a trailer to cause this, either. E.g. you could do one full throttle acceleration, and that could reduce power 5% for subsequent runs, barring a significant cooldown period. The ECU monitors the sensor suite and retards timing, richens mixture, alters valve timing, whatever it takes to preserve themodynamic safety margins, hence engine longevity. Unfortunately most of these result in temporarily reduced power. Worse, to enthusiasts intimately aware of their car's behavior, the perception that throttle response is always changing -- one day quick and crisp, another day somewhat sluggish and mushy.

If what Dinan said is correct, my own theory is much of what is attributed to an "adaptive throttle matrix" is actually varying engine behavior based on changing ambient conditions and engine demands. In a sense there is short-term adaptation based on driver input; more throttle equals more power, resulting in more heat, resulting in retarded timing, etc. But it's not the longer-term "learning adaptation" commonly discussed.

There apparently is adaptive transmission shifting, but that's different than the throttle. My question (and Dinan's answer) was specific to the e46. Maybe other BMW cars like like the new e65 valvetronic do have some kind of learning throttle behavior. For better or worse I wanted to share what he said.

thanks for taking the time to post that. that was fascinating reading.

it would be neat to see a debate between jim conforti and steve dinan in terms of how they approach tuning modern bmw's in all aspects and maybe have someone who actually runs a racing team like will turner (t'motorsport) there also.

Mr Paddle.Shift
08-31-2003, 09:01 PM
Joe, thanks for the elaborate post.

I think some of us losely exchanged the terms between adaptive throttle response and adaptive transmission shifting.The latter is a feature in the Steptronic system. There have been postings a long time ago that some Steptronic drivers experiencing a start from gear 2 instead of gear 1 in D mode. This is because the TCU does adapt to how the driver drives in the D mode in the past.

When the tech cleared the adaptation values yesterday, one of the option was to clear TPS, or throttle position sensor. Although one can easily mistaken this for adaptive throttle response, it is essentially adaptive transmission shifting. Perhaps this won't affect too much in a manual car, but in a Steptronic it does feel very different in D and SD.

IMO, getting the tech to clear the values through the OBD-II port way is the surest way. All it takes if less than 5mins and technically should be done whenenver one modifies the air intake, or any parts of the engine (aftermarket cams, headers etc).

Mr. The Edge
08-31-2003, 09:12 PM
so does the battery trick in fact work for M3's then?

Terry Kennedy
09-01-2003, 05:02 AM
I think some of us losely exchanged the terms between adaptive throttle response and adaptive transmission shifting.The latter is a feature in the Steptronic system. There have been postings a long time ago that some Steptronic drivers experiencing a start from gear 2 instead of gear 1 in D mode. This is because the TCU does adapt to how the driver drives in the D mode in the past.
The battery disconnect does clear at least some settings in the transmission. Before I had the software updated around 2500 miles ago, after I decended the steep hill near my Dad's a few times, my transmission would develop the "clunk" when stopping, which would persist until I disconnected the battery. Then the car would be fine until I visited him a few times and went down the hill. With the software update, this problem has gone away.

The Roadstergal
09-01-2003, 09:47 AM
He confirms with me that that is only for pre-1993 BMWs, not for our E46s anymore.

Hmm, does he know what degree of adaptation, say, a 1986 325e has? Does a chip override it?

pdz
09-01-2003, 09:51 AM
Hmm, does he know what degree of adaptation, say, a 1986 325e has? Does a chip override it?

R'Gal:

i think it's generally agreed that reprogramming of the older cars has a much larger delta in power than the newer cars. it's where the chips work the best.

it's cheaper, too, isn't it? although, you do have to physically put in a different chipset....

pdz
09-01-2003, 10:47 AM
I know this will be controversial, but here goes: yesterday at a lecture I asked Steve Dinan himself do current non-M3 e46s have any adaptive throttle behavior and if so how does that interact with his engine software. I asked him twice to be clear he understood the question.

He said (standing in front of a projected fuel injection map with a pointer in his hand) there's absolutely no adaptive throttle behavior in current non-M3 e46s, and that it's an urban myth that there is. However he said there are adaptive aspects to the ECU software, but not from a driver/throttle standpoint. For example upon starting, the throttle body butterfly quickly drives to full open then close, while the potentiometer generates a curve of that action. Data from that is used to calculate the current linearity of the throttle mechanism, which adapts for mechanical and electrical aging. It's an automatic calibration sequence.

There are also adaptive aspects based on knock/ping detection, ignition timing adaptation, ambient temperature, water temp, etc. He stressed how current sensors and ECUs are so powerful this can have a major difference in perceived (and measured) power. E.g. a dyno run with the hood open vs closed can cause significant power differences. He showed charts illustrating ignition timing being significantly retarded as engine tempeature increased from low normal to high normal (not outside normal). But these are short-term adaptations based on environment and current engine condition, not long term "learning" adaptations based on driver behavior.

IOW a consequence of modern ECU/sensor suites wringing max power from the engine is they also reduce that power to preserve safety margins as engine temp, ambient temp, water temp, etc. increases. This goes far beyond (and is much quicker acting than) pure physical effects such as less dense intake charge because of underhood heat.

It doesn't take a 100F day pulling a trailer to cause this, either. E.g. you could do one full throttle acceleration, and that could reduce power 5% for subsequent runs, barring a significant cooldown period. The ECU monitors the sensor suite and retards timing, richens mixture, alters valve timing, whatever it takes to preserve themodynamic safety margins, hence engine longevity. Unfortunately most of these result in temporarily reduced power. Worse, to enthusiasts intimately aware of their car's behavior, the perception that throttle response is always changing -- one day quick and crisp, another day somewhat sluggish and mushy.

If what Dinan said is correct, my own theory is much of what is attributed to an "adaptive throttle matrix" is actually varying engine behavior based on changing ambient conditions and engine demands. In a sense there is short-term adaptation based on driver input; more throttle equals more power, resulting in more heat, resulting in retarded timing, etc. But it's not the longer-term "learning adaptation" commonly discussed.

There apparently is adaptive transmission shifting, but that's different than the throttle. My question (and Dinan's answer) was specific to the e46. Maybe other BMW cars like like the new e65 valvetronic do have some kind of learning throttle behavior. For better or worse I wanted to share what he said.

upon further thought:

therefore, what gains will software do for non_M cars? we know conforti is coming out with software "soon".

second: Dinan actually says this on their website in kindergartner english: the software does nothing for gains but does adjust throttle response to "MAX" always. so, this begins to all make sense. in the era of the DBW BMW, this is yet another insulator between driver and the road that needs to be "tweaked".

Mr Paddle.Shift
09-01-2003, 12:23 PM
You know what...I might have mistaken the year. Could be pre-1995 instead of pre-1993. DIS was introduced in 1994 thereabouts.

Not entirely sure about E30 modification, I will assume that "Chip" is an actual soldered on modification? The master tech has an E30 325 coupe himself. So I will post the question when I meet him tomorrow. Keep checking back here ok? :D

Hmm, does he know what degree of adaptation, say, a 1986 325e has? Does a chip override it?

Mr Paddle.Shift
09-01-2003, 12:32 PM
You're right Terry. I did recall seeing that in the TIS somewhere...though I can't seem to find it now. Like Nick mentioned, the battery trick probably cleared the values in the volatile memory space. Remember the ECU always compare the new input values with its basic setting and processes an optimal set of output values. These set of new output values will most likely be stored as non-volatile memory to be used in the next stage as basic setting (hence adaptive control) What the battery trick erases is probably the new input values.

The clearing of ECU adaptation values that I am referring to are related to oxygen sensor, catalyst, misfire, evaporative system, secondary air and fuel system readings. Looks like these have to be done through the OBD-II port.

Btw how was Bimmerfest?



The battery disconnect does clear at least some settings in the transmission. Before I had the software updated around 2500 miles ago, after I decended the steep hill near my Dad's a few times, my transmission would develop the "clunk" when stopping, which would persist until I disconnected the battery. Then the car would be fine until I visited him a few times and went down the hill. With the software update, this problem has gone away.

Nick325xiT 5spd
09-01-2003, 12:58 PM
You know what...I might have mistaken the year. Could be pre-1995 instead of pre-1993. DIS was introduced in 1994 thereabouts.

Not entirely sure about E30 modification, I will assume that "Chip" is an actual soldered on modification? The master tech has an E30 325 coupe himself. So I will post the question when I meet him tomorrow. Keep checking back here ok? :D
If it's going to change in a given year, I would think that it would be pre-1996, given that 1995 was the last OBD-I year.

The Roadstergal
09-01-2003, 01:48 PM
You know what...I might have mistaken the year. Could be pre-1995 instead of pre-1993. DIS was introduced in 1994 thereabouts.

Not entirely sure about E30 modification, I will assume that "Chip" is an actual soldered on modification? The master tech has an E30 325 coupe himself. So I will post the question when I meet him tomorrow. Keep checking back here ok? :D
Yes, actual mount-it-chip... I'm just wondering if the engine has adaptation, and if the adaptation effect is comparable to the chip in effect, either positive or negative... becuase from the various dynos, software has a heckuvan effect on the etas...

Danke! The Master came to Strictly, but I was entertaining a friend instead. :(


(I've been searching eBay for used Dinan chips for a while... :eeps:)

e46supra
09-01-2003, 05:32 PM
To add my 2 cents:

I have a 93 325is and have a DINAN EPROM chip installed in it.

I remember before I had the chip and installed my ECIS with the stock ECU, disconnecting the battery made the car run extremely better with the intake. I would do so every time I changed the oil.

With a complete battery replacement (OE) and installation of the DINAN EPROM, the car runs the best right before my bi-monthly oil change. Right before I disconnect the battery for the duration of my oil change procedure.

When I did the same on my E46 (pre-shark injector) and my Dad's E39 540i (pre-DINAN), I sense NO change what so ever.

Mr Paddle.Shift
09-01-2003, 05:35 PM
Sorry about that.Yes, pre-1996 sounds better.

If it's going to change in a given year, I would think that it would be pre-1996, given that 1995 was the last OBD-I year.

Mr Paddle.Shift
09-01-2003, 05:36 PM
Thanks for the note, e46supra. :thumbup:

To add my 2 cents:

I have a 93 325is and have a DINAN EPROM chip installed in it.

I remember before I had the chip and installed my ECIS with the stock ECU, disconnecting the battery made the car run extremely better with the intake. I would do so every time I changed the oil.

With a complete battery replacement (OE) and installation of the DINAN EPROM, the car runs the best right before my bi-monthly oil change. Right before I disconnect the battery for the duration of my oil change procedure.

When I did the same on my E46 (pre-shark injector) and my Dad's E39 540i (pre-DINAN), I sense NO change what so ever.

PABS
09-03-2003, 07:03 AM
Hmm...this really got me thinking...I have the DinanS2 in my 330ci w/5spd.

There is no doubt the throttle/engine behaves differently at times...sometimes it feels very responsive and sometimes not....I usually wait for the engine to warm up before taking it up the revs, but even after warm up and prolonged driving it changes.

I've always attributed the slugish engine response to the DSC intruding or the clutch doing it's self adjusting thing...with so many variables to consider I suspect it is a combination of all..

There must be some truth to what Joe says (ie Dinan said) because on cold start the whole throttle/engine is very sensitive...what I mean it exhibits a very non-linear curve...what I mean is that early in the morning when I first start driving it is very difficult to get any smooth throttle/clutch behavior....as it warms up it gets much smoother

The early morning behavior reminds me of engines with radical cam timing that don't like to run at low rpm's.

So bottom line I think is that Dinan's claims are correct..the software does nothing for power but does significantly alter the throttle/butterfly dynamics...

Just my opinion..YMMV