m20 ecu reset?

[moots]

Whenever i disconnect the battery (for 1 reason or the other) and reconnect,the idle becomes crappy and at times the engine dies off because of the low idle speed and the engine hesitates and falters at times when starting off from standstill.At cruise no problems.It takes 2 days for it to becum normal.Anybody experienced this b4?I suspect the ECU internal battery dah kaput and kenot remember previous settings such that the ecu is 're-learning' the map.I don't have this issue with the e30 though.I didn't have this problems during my early ownership of the car.(had car since '99),just maybe the last 2 years I noticed this happening.Anybody with any explanation..........and a cure maybe?

 

[nsbone]

I oso get the same problem. Some said to let the switch on for some minutes before crank the motor, after replacing the battery. Some said, if battery is disconnected long enough eg .5hr or so, then that could happen.

 

[jeffreyewe]

I'm having a similar problem. My idling becomes erratic and low, sometimes dies off as well.

Does the ECU have something to do with it?


Sorry to Hijack your thread...moots

 

[ehoe]

Yup that happens to me too. It takes several days before the idling returns to normal. What I do is I manually adjust the idling RPM to slightly higher so that it doesn't stall on me during those first few days. Then once the ECU relearns the settings I adjust back the idling to normal.

I did hear from a mechanic once before that another way you can do is after reconnecting the battery, start the car up and leave it running at idle for maybe an hour or two and it should re-learn back the settings. Whatever way, there is no 'quick' way of getting the ECU to re-learn so might as well just use the car as normal and let it relearn on its own. Just have to put up with the rough idling for the first few days.

Anyone know of a faster way to do the ECU relearning process?

 

[535i]

Trying switching on the car (not crank or start the car .. u can see all the lites being displayed). Hit the accelerator pedal to metal for 10 seconds.
Switch off and then crank the car ... That might help. Read somewhere but cannot remember ...

 

[skinhead]

it oso happen to me lately.... i diskonek the battery oni 10 minutes oso happen.. but after drive for 2hrs or so.. idle normalized. if not 1st gear car move... press clutch to enggage 2nd gear engine die... how to drive liddat ??? but in my case the ilde is not bad but the engine would die whenever i depress the clutch to enggage higher gears... wud i do ( i tot u advice me b4 wut!!! ) i let the car idle for 30mins or so b4 redrive...

 

[dvng]

THIS IS THE ONLY WAY IT WORKS! When the battery is disconnected, the ecu resets itself to its default mode, which explains the stalling and sputtering of the engine especially during idle and deceleration. There is no internal battery in the ecu, i've dismantle it b4 whilst installing a remapped chip. Here is what you need to do to achieve quick fix without meddling with the idle,afm or diconnect or reconnect the battery. The secret is the ICV. Remove the ICV and note where the arrow points. Now, reorientate the arrow so that is points the opposite direction and reconnects the ICV. The idle will immediately be raised to approx, 1200rpm or 1100rpm. Drive around for a day or two. Then revert the the ICV to its original position, and wahlah your idle is back to normal. Works everytime, anytime, trust me. The reversing of the airflow of the iCV tricks the ecu going into manual idle which opens up the afm, thus u will have stable idle although on the high side. This prompts the ecu to switch to a higher idle. When u switch back, the ecu, will readapt with the correct afm flow and thus your idle returns to normal. After that, go to your mechanic and adjust the CO level. This is to ensure your car is not runnin too rich. Good Luck.

 

[stusj]

Last 2 days, my car has the same 'erractic idle' while stationary and gear in 'D'. However, I have not removed my battery. Is this cause the same - ie. ECU ?

Wow.. do we have an epidemic on our hands ? or the internal clocks on the ECU says that the year 2005 is just too long for the car to be still moving around ?

Mine is a 1990 e34 m25

Also, what is this ICV thing ?

 

[dvng]

The ecu is not the problem since yours is probably on the Motronic 1.3. The main cause could be the throttle position switch, clog ICV or your CO value is too high. The problem is the m20 engine requires experience tuning, dont just increase the airflow for higher idle rpm this will cause the engine to idle hunt. Keep Co value between 1.0 and 1.5%.

 

[moots]

Aiyaaahhhh....yesterday after work,eager to go home,start the car,no crank :angry: ,horn weak,pwr window don't work!Damn battery(Yokohama)!Had it since april 2003.So push started(with help of crs) and dropped by a shop(lucky still open at 1845h).Changed it (rm 150 some cheapo brand) and guess what.....no lah no need to guess........ the "crappy idle once battery disconnected" syndrom is back :angry: :angry: :angry: !
Anyways,once home,I disconnected the battery again to properly clean the battery tray and did:
1.short +ve to -ve leads for 10 mins(to cleanse ecu memory?)
2.switch car on(not start)for 10 mins
3.idled the car for 1/2 hr (this morning)b4 driving

NO!Nothing!Nyet!Same crappy idle with the engine dying 3 times(at traffic lights).Well,looks like i'll have to rough it out for the next 2 days then!!!

DVNG...
I have gone thru the ICV re-positioning thingy but not because of this 'diskonek batt'reason.When I first bought the car(1999),I noticed that the ICV was already positioned wrongly.So I reverted it to normal but the idle was crap.
So I put it back(albeit the wrong way).Idle OK at 8k rpm.But in 2003, I gatal again and went to reposition the ICV the correct way.Idle was crap for 1 day and I guess the ecu adapted to this new position and ran fine till now.
So if the trick is to re-oriented the ICV,but it still takes 2 days(per yr advise) for the idle to stabilise,then I might just as well let the idle stabilise itself without touching the ICV coz it takes the same number of days to do that.SO.....anyone else with a quicker method?

note: I have had the batt disconnected b4 during my early ownership of this car but this crappy idle thing was not there earlier.this came only during the last 2/3 years.

 

[ngkm]

Originally posted by moots@Jan 26 2005, 07:38 PM
note: I have had the batt disconnected b4 during my early ownership of this car but this crappy idle thing was not there earlier.this came only during the last 2/3 years.

Moots,
Agree with ya. Did not notice this problem earlier in the car.
Guess there is some built in storage capacitor or some temp batts which is no longer working. Or was that why it took soooo long to get my car back from AB during service (they could have idle'd it until it returned to normal before returning it).

Someone did suggest to create a temp 12v supply via the lighter jack when the main batts is taken off to avoid this. However, in this scenario, we still can't work on the car's electrics as its circuitry could still be "hot". And its useless against accidental/unplanned battery outage, like your current scenario.

cheers.

 

[sazli]

Guess there is some built in storage capacitor or some temp batts which is no longer working. Or was that why it took soooo long to get my car back from AB during service (they could have idle'd it until it returned to normal before returning it).


Try this url: http://www.bmwe34.net/E28/Repairs/Repairs_main.htm

click dashboard Repair

maybe that battery also used for back-up memory???

 

[moots]

Originally posted by sazli@Jan 27 2005, 03:10 PM


Try this url: http://www.bmwe34.net/E28/Repairs/Repairs_main.htm

click dashboard Repair

maybe that battery also used for back-up memory???

Brudder Sazli,
This battery is for the SIL......but then again...could it be that ....hmmmmm...i wonder if it's related.....hmmmmmmmmm.... :unsure:

i've had the car for six yrs now......those lithium ion batteries life is approx 6 years.....but my SIL is still working fine and i am still able to reset it....in fact I just did a reset last month...........................normal...........hmmmmm(in desperation) h34r:

 

[dvng]

yes, is still takes 2 days for the ecu to relearn even with ICV reposition, but then at least the car is driveable without it stalling when you decelerate at standstill, and even when stationary whilst you are manuevering the steering. It is really annoying, it even stalls when you are making a u turn in a busy road, very terryfying. so i rather have a driveable car thn waitin for the ecu to relearn with all the unpredictable stalling.

 

[ehoe]

So for those that have this ECU losing its setting problem, how do you go about changing your battery assuming its due for a change?.

1) Use jumper cables to connect the existing battery to the new battery then only removing the old battery. This will avoid power lose and thus no lose of ECU settings.

or

2) Start the car and let it run then remove the old battery and replace with a new battery. By starting the car, the power is supplied by the alternator whilst the battery is replaced.

Are there any implications on using any of the above two methods?. i.e it won't fry any of the electronics or damage the alternator, etc??.

Anyone got a better way to go about it?.

 

[Zoggee]

okay...Magicfox has the BMP reset tool with him.I'll ask him to take it along for this weekend TT at Soul Out.So you guys can do whatever you with it.

well at least....maybe it'll helps. B)

 

[ehoe]

Just curious, isn't the reset tool meant to just reset the service or inspection lights?.

How will it help in those with the M20 ECU resetting problem when disconnecting the batt?. Sori for my blurness....just wanted to clarify.

 

[Zoggee]

Originally posted by ehoe@Feb 28 2005, 01:52 AM
Just curious, isn't the reset tool meant to just reset the service or inspection lights?.

How will it help in those with the M20 ECU resetting problem when disconnecting the batt?. Sori for my blurness....just wanted to clarify.

yeah... you are right.just to reset the inspection/service light. at least it's going to be there to check for faulty codes/parts. Very useful and free of charge!!

Just be there at Grand TT ..this is why I post it up here about the tools. B)I'll be reseting somene's M50...so can you..!! B)

 

[ehoe]

Had my batt replaced recently and as usual had the bad idling after disconnecting the battery. This time noticed that it took a lot longer for the ECU to relearn the settings (almost a week!).

So didn't seem right so I took out the ICV and had it cleaned and serviced and disconnected the batt for it to relearn again. The ICV was really dirty after so many years and I guess the sliding flap inside was restrictive due to the dirt.

After cleaning the ICV and reconnecting the batt (for the 2nd time), the ECU relearned the settings in a mere few hours!. So for those whom have this bad idling problem after disconnecting the batt, check if your ICV is clean or not. Hope this helps.....

 

[E34EuroTouring]

Hi Ehoe,

There is another way of preserving the ECU paramters. Using the cigarette lighter and wire it correctly to a 9volt AverReady battery. Then you can unplug the main battery and change it.

Rdgs.