Does the ECU take time to settle down?

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1963paul
Joined: Sat 19 Jul, 2014 14:19
Posts: 89

  Z3 roadster 2.0

Does the ECU take time to settle down?

Post by 1963paul » Tue 19 Jul, 2016 23:57

Just had a perished hose replaced on the air intake ( was "hunting" on tick over, then plugs were fouling up, then start to mis-fire), that's all ok now, but on my 1st drive since it was replaced, I noticed it's a bit "sluggish", there a steep hill near where I live where before it would go up in 2nd gear, and gain speed, but now it really struggled. On the motorway,it was fine at speed, but getting up to speed wasn't as quick as before. Now I have read somewhere that the ECU takes time to settle down if something has changed, and the car has had the hunting problem for a few weeks before I found the split hose, so does the ECU need time to re-adjust to the correct air/fuel mixture, after running so long with air being sucked in the split hose? It's a 1999 2litre roadster.

mrscalex
Joined: Fri 13 Mar, 2015 09:14
Posts: 803

  Z3 roadster 1.9

Re: Does the ECU take time to settle down?

Post by mrscalex » Wed 20 Jul, 2016 00:04

Pingu told me this once which bears out your theory but doesn't really confirm it.

Modern cars tweek the ECU settings so the engine can be pretty knackered, but still sound as sweet as a nut. The readouts on the INPA will show you the settings used to the ECU to make the engine run. There is a reset button that will restore the original settings. If the engine is pretty ropy and you reset the ECU, the engine will sound like a bag of spanners for about 10 minutes before the ECU has restored the parameters needed to make the engine run.
ImageImage
1999 Z3 1.9 Boston Green (Dimitri) - My brother's car owned from new and restored by me
2001 Z3 2.2 Topaz Blue (Trudy) - My car rebuilt from a write-off
2002 Z3 2.2 Titan Silver (Okus) - Project car waiting for a new engine
2001 Z3 2.2 Topaz Blue (Debra) - Donor car/breaker
1998 Z3 1.9 Boston Green (Allsworth) - Donor car/breaker now gone to Z3 heaven
Always happy to try and help with spares :)

1963paul
Joined: Sat 19 Jul, 2014 14:19
Posts: 89

  Z3 roadster 2.0

Re: Does the ECU take time to settle down?

Post by 1963paul » Wed 20 Jul, 2016 00:14

So, do I need to re-set the ECU, or drive it around?...and how long before it re-tunes it self?' 10 mins, couple of days, so many miles?...
( thanks for quick response, must admit this heat is making sleeping a bit difficult)! :rtm:

mrscalex
Joined: Fri 13 Mar, 2015 09:14
Posts: 803

  Z3 roadster 1.9

Re: Does the ECU take time to settle down?

Post by mrscalex » Wed 20 Jul, 2016 00:24

Sorry, no idea. Just a bit of encouragement it might still happen.
ImageImage
1999 Z3 1.9 Boston Green (Dimitri) - My brother's car owned from new and restored by me
2001 Z3 2.2 Topaz Blue (Trudy) - My car rebuilt from a write-off
2002 Z3 2.2 Titan Silver (Okus) - Project car waiting for a new engine
2001 Z3 2.2 Topaz Blue (Debra) - Donor car/breaker
1998 Z3 1.9 Boston Green (Allsworth) - Donor car/breaker now gone to Z3 heaven
Always happy to try and help with spares :)

NZ00Z3
Joined: Thu 23 Jun, 2016 02:26
Posts: 61

  Z3 roadster 3.0i

Re: Does the ECU take time to settle down?

Post by NZ00Z3 » Wed 20 Jul, 2016 05:54

It will take a couple of tanks of fuel for the ECU to learn. It will first of all set new short term fuel trim tabs which will make the car feel better when it hot and in closed loop fuel management. It will still feel like crap when cold. After a couple of tanks of gas the short term trim tabs will be moved to the long term trim tabs. At this point the car will feel good event when cold.

This weekend looks like a great time for a road trip. Hey its summer where you are after all.

1963paul
Joined: Sat 19 Jul, 2014 14:19
Posts: 89

  Z3 roadster 2.0

Re: Does the ECU take time to settle down?

Post by 1963paul » Wed 20 Jul, 2016 06:10

Ok, so just drive it and see what happens over next 2-3 weeks. In this weather I am using my bike more often then not, so a couple of tanks of fuel may take longer 8-) ...I actually use the Z more in the winter :shock:
Thanks for the responses.

deni2s
Joined: Mon 25 Mar, 2013 22:02
Posts: 747

  Z3 roadster 2.8

Re: Does the ECU take time to settle down?

Post by deni2s » Fri 22 Jul, 2016 12:13

I would still suggest reseting the adaptations, that should make instant effect without torturing your engine with incorrect settings. 2 minutes job if you have the cable and INPA.

mrscalex
Joined: Fri 13 Mar, 2015 09:14
Posts: 803

  Z3 roadster 1.9

Re: Does the ECU take time to settle down?

Post by mrscalex » Fri 22 Jul, 2016 12:21

deni2s wrote:I would still suggest reseting the adaptations, that should make instant effect without torturing your engine with incorrect settings. 2 minutes job if you have the cable and INPA.
That's presumably what pingu was talking about. It's probably what I would do. But as it sounds reasonably scary and I've never done it myself I wasn't going to suggest that.

I intend to try it on my breaker's engine before it goes off for scrap.
ImageImage
1999 Z3 1.9 Boston Green (Dimitri) - My brother's car owned from new and restored by me
2001 Z3 2.2 Topaz Blue (Trudy) - My car rebuilt from a write-off
2002 Z3 2.2 Titan Silver (Okus) - Project car waiting for a new engine
2001 Z3 2.2 Topaz Blue (Debra) - Donor car/breaker
1998 Z3 1.9 Boston Green (Allsworth) - Donor car/breaker now gone to Z3 heaven
Always happy to try and help with spares :)

1963paul
Joined: Sat 19 Jul, 2014 14:19
Posts: 89

  Z3 roadster 2.0

Re: Does the ECU take time to settle down?

Post by 1963paul » Sun 24 Jul, 2016 15:03

Just like to say, it has "settled down", and all is ok now...took about 10 miles before it started to feel like it should :)

BeemerBoyo
Joined: Mon 10 Feb, 2014 10:51
Posts: 96

  Z3 roadster 2.2i
Location: Teesside

Re: Does the ECU take time to settle down?

Post by BeemerBoyo » Mon 25 Jul, 2016 07:00

Just for interest some time ago I fitted a pipercross air filter to my 2.2 Z3Sport. Two ex Preston Hall BMW mechanics look after my car (AW Auto works) and they said to reset the ecu back to default to remove both battery leads from the battery and then short them for 10 seconds with a metal spanner. I followed this instruction and then went for a test drive for 30 miles with the new air filter fitted. It must have worked as the engine did feel a bit lethargic to start with but after 20 miles or so it was pulling very well, better than before.

You assume these guys know what they are doing so take this advice as gospel.

Anybody else heard/done this before?
2002 E37 BMW Z3 2.2 Sport
2008 E93 BMW 3 series 325i m sport convertible

Previous BMW cars

2007 E87 BMW 1 series 120D
2013 F21 BMW 1 series 120D

deni2s
Joined: Mon 25 Mar, 2013 22:02
Posts: 747

  Z3 roadster 2.8

Re: Does the ECU take time to settle down?

Post by deni2s » Mon 25 Jul, 2016 08:48

BeemerBoyo wrote:Just for interest some time ago I fitted a pipercross air filter to my 2.2 Z3Sport. Two ex Preston Hall BMW mechanics look after my car (AW Auto works) and they said to reset the ecu back to default to remove both battery leads from the battery and then short them for 10 seconds with a metal spanner. I followed this instruction and then went for a test drive for 30 miles with the new air filter fitted. It must have worked as the engine did feel a bit lethargic to start with but after 20 miles or so it was pulling very well, better than before.

You assume these guys know what they are doing so take this advice as gospel.

Anybody else heard/done this before?
Doesn't sounds like a proper way to reset ECU. Actually I am quite sure it didn't reset ECU, just after 30 miles ECU adapted to new airflow. You don't need to reset ECU itself, you need to reset adaptations table in ECU. You can do that by connecting diagnostics software (like INPA) to the ECU, and not by shorting something with a spanner - this sounds more like some hack, which in best case shouldn't do anything and in worst case can damage ECU.

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lightning
Joined: Tue 27 Nov, 2007 08:15
Posts: 814

  Z3 roadster 3.0i
Location: Stockport

Re: Does the ECU take time to settle down?

Post by lightning » Tue 26 Jul, 2016 08:03

This method is a recognised way to reset the ECU and is used by the RAC.
It's called a "power latch".

The procedure is as follows.
Warm the engine up to operating temperature.
Turn the engine off then turn the ignition back on, but do NOT start the engine.
Take off the battery positive lead.
Short the lead to earth for ten seconds.
Turn off the ignition.
Reconnect the battery positive lead.
Turn on the ignition, WAIT TEN SECONDS then start the engine.

Drive the vehicle normally. (No need to go through every type of driving or thrash the engine etc) The ECU/PCM will be reset and it does not "learn how you drive" so much as re align itself to the engine, as mentioned above.
Last edited by lightning on Tue 26 Jul, 2016 18:42, edited 1 time in total.

siwilson
Joined: Fri 19 Jun, 2009 10:54
Posts: 783

  M roadster S54
Location: Horley

Re: Does the ECU take time to settle down?

Post by siwilson » Tue 26 Jul, 2016 14:22

I think for clarity it would be useful for someone with INPA to try this.

1. Use INPA or DIS to check adaptions are in place.
2. Reset adaption use RAC method above.
3. UNse INPA or DIS to check adaptions have indeed been reset.
4. Report back here on how it went.
2001 M roadster S54 Laguna Seca Blue

mrscalex
Joined: Fri 13 Mar, 2015 09:14
Posts: 803

  Z3 roadster 1.9

Re: Does the ECU take time to settle down?

Post by mrscalex » Tue 26 Jul, 2016 14:43

siwilson wrote:I think for clarity it would be useful for someone with INPA to try this.

1. Use INPA or DIS to check adaptions are in place.
2. Reset adaption use RAC method above.
3. UNse INPA or DIS to check adaptions have indeed been reset.
4. Report back here on how it went.
You may be short on volunteers! But I will happily try this on my breaker sometime - not sure when! Will report it back here if no one else has done it in the meantime.
ImageImage
1999 Z3 1.9 Boston Green (Dimitri) - My brother's car owned from new and restored by me
2001 Z3 2.2 Topaz Blue (Trudy) - My car rebuilt from a write-off
2002 Z3 2.2 Titan Silver (Okus) - Project car waiting for a new engine
2001 Z3 2.2 Topaz Blue (Debra) - Donor car/breaker
1998 Z3 1.9 Boston Green (Allsworth) - Donor car/breaker now gone to Z3 heaven
Always happy to try and help with spares :)

BeemerBoyo
Joined: Mon 10 Feb, 2014 10:51
Posts: 96

  Z3 roadster 2.2i
Location: Teesside

Re: Does the ECU take time to settle down?

Post by BeemerBoyo » Mon 01 Aug, 2016 07:09

To be fair I did use the wrong terminology. The object of shorting out the two battery cables was to allow the ecu to learn the new airflow of the new air filter. I suppose this just deletes some short term memory setting just like clearing the cache on a PC but the operating system is not touched and remained intact.

It did seem to work but I really have no data to back this up in terms of before and after.
2002 E37 BMW Z3 2.2 Sport
2008 E93 BMW 3 series 325i m sport convertible

Previous BMW cars

2007 E87 BMW 1 series 120D
2013 F21 BMW 1 series 120D

handsomejackuk
Joined: Sat 18 Jun, 2016 11:35
Posts: 295

  Z3 roadster 1.9
Location: Blaenau Gwent South Wales...

Re: Does the ECU take time to settle down?

Post by handsomejackuk » Wed 12 Oct, 2016 16:18

see i seem to think that by disconnecting the battery it does sort of reset something, as i disconncted mine a few times to do the seat bushes, and to change my steering wheel, and every time after i reconnected battery i get real bad fuel consumption, but it has settled down again after a few tankfulls so is the ecu restting adaptions with power off ?

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pingu
Joined: Fri 30 Apr, 2004 17:01
Posts: 3337

  M roadster S50

Re: Does the ECU take time to settle down?

Post by pingu » Wed 12 Oct, 2016 18:11

The reset trick ensures that the +ve and -ve have a zero potential difference.

I've never done it with the ignition on, but it makes sense as there will be circuits that are only "live" when the ignition is on.

If I were to do it, I would...

1. Switch everything off and remove the key.
2. Disconnect the earth lead.
3. Disconnect the positive lead.
4. Reconnect the earth lead to the negative pole of the battery.
5. Connect the positive lead to the negative pole of the battery using a jump cable (very low resistance).
6. Turn the key as if to start the car. Hold in the start position for ten seconds. Nothing should happen.
7. Allow the key to return to the normal running position (ignition). Leave it there for ten seconds. Nothing should happen.
8. Turn the key back to the first click (auxilliary). Leave it there for ten seconds. Nothing should happen.
9. Remove the key.
10. Remove the jump cable and disconnect the positive lead from the negative pole of the battery.
11. Disconnect the earth lead from the negative pole of the battery.
12. Connect the positive lead to the positive pole of the battery.
13. Connect the earth lead to the negative pole of the battery.
14. Start the car and drive as normal.

I don't think you will have reset anything, but you will have ensured that all the electronics in the car are at the same baseline potential difference (zero volts).


BEWARE: If you disconnect any lead with the ignition on there will be a spark when you disconnect and reconnect, so make sure the battery is well ventilated if you do it (and I do not recommend that you do). [edit: and you may permanently damage the ECUs]

BEWARE: It is very bad practice to not disconnect the earth lead first. If you disconnect the positive lead first and you touch (or even get very close to) the car body with a spanner, you risk a short circuit. The spanner will get very hot, very fast. I've seen (and heard) it happen. :shock:
Last edited by pingu on Fri 14 Oct, 2016 01:12, edited 1 time in total.
Pingu

handsomejackuk
Joined: Sat 18 Jun, 2016 11:35
Posts: 295

  Z3 roadster 1.9
Location: Blaenau Gwent South Wales...

Re: Does the ECU take time to settle down?

Post by handsomejackuk » Wed 12 Oct, 2016 18:50

always remember my dad doing some work on his car, and there used to be open cells on tops of the battery i.e. all the cells were coming out the top of the battery and connected in series, he leant across the battery with a casio watch with a stainless steel strap. and you can imagine what happened next, may have only been 1.5v to 2v but the current was enough to make the stainless steel watch band glow red hot, and give him severe burns to his wrist..

Also i remember my mate with a mk2 escort accidentally let his bonnet stay short across the positive terminal of the battery that also glowed very red hot..... and was quite a site to see....

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lightning
Joined: Tue 27 Nov, 2007 08:15
Posts: 814

  Z3 roadster 3.0i
Location: Stockport

Re: Does the ECU take time to settle down?

Post by lightning » Wed 12 Oct, 2016 20:25

The ECU may take a few miles to align itself to the engine after the battery has been disconnected for a while.

In practise though, l have never noticed much difference after the battery was disconnected. I think it's mainly to do with low speed running and idle, although that's only what l have read online.
Last edited by lightning on Fri 14 Oct, 2016 21:36, edited 1 time in total.

NZ00Z3
Joined: Thu 23 Jun, 2016 02:26
Posts: 61

  Z3 roadster 3.0i

Re: Does the ECU take time to settle down?

Post by NZ00Z3 » Wed 12 Oct, 2016 21:29

Some of the DME/ECU reset information here is starting to sound like 1980's and Interweb folk lore. Every one has read it somewhere on the interweb so it must be true.

With the introduction of the emission's laws and the unification of protocols to ODB2, the design laws on resetting DME information has been set by the various bodies in Europe and USA. They all require the DME program and operating variable to be stored in non-volatile memory. A battery disconnection or 0V reset will not work. You need the appropriate software/scanner to write the data message to reset or change the variables.

The only exception is the BMW paper clip service light reset, which has nothing to do with the operation or emission control of the engine.

If you want to reset your adaptions, read and clear error codes etc, purchase software or a scanner with the required capability.

handsomejackuk
Joined: Sat 18 Jun, 2016 11:35
Posts: 295

  Z3 roadster 1.9
Location: Blaenau Gwent South Wales...

Re: Does the ECU take time to settle down?

Post by handsomejackuk » Wed 12 Oct, 2016 23:44

just curious but does the ecu have a battery backed memory chip like a computer bios, that maybe over the years could go flat and then when the vehicle battery is disconnected the battery backed eprom reverts to its default value...?

its only a thought, and not having taken the ecu apart i would not know...

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BladeRunner919
Joined: Fri 17 Feb, 2012 20:18
Posts: 2221

  Z3 roadster 1.9

Re: Does the ECU take time to settle down?

Post by BladeRunner919 » Thu 13 Oct, 2016 16:51

No, it uses non-volatile memory that doesn't require power to store its settings. As NZ00Z3 states, disconnecting the battery, fiddling around with the leads etc will only achieve one thing - requiring you to enter the security code into the stereo. Nothing else.

handsomejackuk
Joined: Sat 18 Jun, 2016 11:35
Posts: 295

  Z3 roadster 1.9
Location: Blaenau Gwent South Wales...

Re: Does the ECU take time to settle down?

Post by handsomejackuk » Thu 13 Oct, 2016 22:29

ahh well that rules that out then.... grrrrr :-)

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pingu
Joined: Fri 30 Apr, 2004 17:01
Posts: 3337

  M roadster S50

Re: Does the ECU take time to settle down?

Post by pingu » Fri 14 Oct, 2016 01:09

Some night-time reading...

BMW Vehicle Communication Software Manual

If the answer is not in here, then it probably can't be answered by anyone outside of BMW :) .
Pingu

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BladeRunner919
Joined: Fri 17 Feb, 2012 20:18
Posts: 2221

  Z3 roadster 1.9

Re: Does the ECU take time to settle down?

Post by BladeRunner919 » Fri 14 Oct, 2016 08:07

handsomejackuk wrote:ahh well that rules that out then.... grrrrr :-)
Can I suggest that you go back to basics and consider that you are attributing the symptoms to the wrong problem? Reading your original post, I'm not sure that I would expect plugs to foul if you had an unmetered airleak. You'd actually have a lean-running situation. I appreciate that the ecu would possibly be increasing fuelling to stop the car from stalling, but I do wonder whether the airleak you found wasn't your real problem.

Have you checked the plugs again recently? I'm wondering if you have an overfuelling problem that's reducing power and that has become more apparent because you've fixed the airleak that was actually helping to lean the mixture back a bit.

You really need to hook up to INPA and see what's going on in real time, otherwise all we can do is speculate (which is all I'm doing).

Del
Joined: Sat 19 Nov, 2011 18:35
Posts: 2122

  Z3 roadster 1.9

Re: Does the ECU take time to settle down?

Post by Del » Fri 14 Oct, 2016 09:24

The system on these cars is fairly old these days and I'm afraid I don't buy the concept that it takes weeks, and several tanks of fuel, for the ECU to "re-adjust" to a fault being corrected. Are we saying that if I ran my car with 3 spark plugs, then replaced the fourth, that it would then take up to two tanks of fuel for it to cease firing on three cylinders? Whenever I've replaced a truly faulty sensor on a car (ones newer than my Z3) the improvement has been instant. As bladerunner says, if the car still isn't running properly it is likely there is still a fault and as these cars are older, if it isn't the obvious it can be trickier things to pin down like sensors, vacuum pipes, vanos (6 cylinder), Disas, PCVs, throttle butterfly valves etc

deni2s
Joined: Mon 25 Mar, 2013 22:02
Posts: 747

  Z3 roadster 2.8

Re: Does the ECU take time to settle down?

Post by deni2s » Fri 14 Oct, 2016 11:43

Del wrote:The system on these cars is fairly old these days and I'm afraid I don't buy the concept that it takes weeks, and several tanks of fuel, for the ECU to "re-adjust" to a fault being corrected. Are we saying that if I ran my car with 3 spark plugs, then replaced the fourth, that it would then take up to two tanks of fuel for it to cease firing on three cylinders? Whenever I've replaced a truly faulty sensor on a car (ones newer than my Z3) the improvement has been instant. As bladerunner says, if the car still isn't running properly it is likely there is still a fault and as these cars are older, if it isn't the obvious it can be trickier things to pin down like sensors, vacuum pipes, vanos (6 cylinder), Disas, PCVs, throttle butterfly valves etc
ECU has some adaptations values which are being adjusted all the time while driving using knock sensors and o2 sensors info. It's a good practice to reset errors and adaptations manually (using INPA or similar tools) after changing anything regarding AFR or it's measuring. Otherwise it can take some mileage depending on driving style to readjust.

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