[malcolm]

thanks man will check the link

[dadu]

Since this thread was started in 2004, let me post the known updated method of resetting the ECU/ ECM.

Step 1: Ensure the vehicle is warmed up/ at its normal operating temperature (i.e. take it for a drive or let it idle for 15 minutes).

Step 2: To reset the ECU you simply have to unplug/ disconnect the negative battery cable, wait for 5-10 minutes.

Step 3: Pump brakes once/twice, this eliminates the requirement for leaving it for longer periods, as it drains the residual charge from the entire system.

Step 4: Put the negative cable back on the battery.

Step 5: Turn the vehicle ON, DO NOT TOUCH ANYTHING. DO NOT ACCELERATE, let the car idle for roughly 10 minutes or until the car is idling smooth at lower rpm's.

Step 6: Turn the ignition off. ONCE AGAIN, DO NOT TOUCH ANYTHING OTHER THAN THE KEY. Immediately turn the ignition back ON after you have switched OFF, this will store the new settings for your ECU.

These steps will properly reset your ECU, drive normally. The Vehicle will feel sluggish initially but will catch up once the ECU learning curve is over.

[Mr.Bangalore]

thank you dadu for the steps..
will try it out on my car

[dadu]

Before doing it, ensure you will not change anything very soon, i.e. fuel quality (normal/premium), exhaust, performance filter etc etc.

If you intend to, first do those changes and then reset.

Originally Posted by Mr.Bangalore

thank you dadu for the steps..
will try it out on my car

[zoomingbhat]

Originally Posted by dadu

Step 3: Pump brakes once/twice, this eliminates the requirement for leaving it for longer periods, as it drains the residual charge from the entire system.

.

Could you explain the above point.I didnt understand the need for it

[Rehaan]

Originally Posted by zoomingbhat

Could you explain the above point.I didnt understand the need for it

I think he means pump the brakes so that the brake lights come on (if at all) and drain the remaining current that might be stored at various places in the circuit (eg. the capacitor for your 6million watt ICE setup?). Not sure i can think of any other reason for it...?

cya
R

[sudev]

Originally Posted by zoomingbhat

Could you explain the above point.I didnt understand the need for it

AFAIK With battery terminal out any residual charge will be drained by action of brake switch trying to light up the brake bulbs....

[dadu]

Thanks Rehaan and Sudev for confirming, its for the same reason.

[kapilsharma80]

Dadu, sometime back i was told by a fiat engineer (who had come to inspect my car) that ECU could only be completely reset through the computer. Disconnecting the - ve terminal would only remove 'intermittent errors' from the ecu's memory.

I am confused!! What's your take on this brother?

[dadu]

We are not reflashing the ECU we are just resetting the ECU to factory default setting removing any learnt memory maps.

Originally Posted by kapilsharma80

Dadu, sometime back i was told by a fiat engineer (who had come to inspect my car) that ECU could only be completely reset through the computer. Disconnecting the - ve terminal would only remove 'intermittent errors' from the ecu's memory.

I am confused!! What's your take on this brother?

[santosh.s]

I have a couple of questions-
1. Is this ECM "learning" a continuously ongoing process, or does it last for some initial period following reset?
2. In case it is not continuous, how to identify that learning curve is over or not yet?

I suppose whatever you do during learning would set the direction of tuning, inclined towards either performance or mileage. So, shouldn't one need to know that period and be consistent in what you are trying to program?

[dadu]

Its not a continuous learning forever but with some exceptions.

Once its reset it will try to follow a map as defined in the ECU and based on your driving and remember those values. This is usually achieved within the first 100-150kms of driving after the reset.

But the ECU is also constantly monitoring the fuel/Air ratios wrt to the timings by using the O2 sensors and engine knock sensors etc. So it will manipulate those parameters again(as required) to come close to the map defined in a closed loop ECU.

Originally Posted by santosh.s

I have a couple of questions-
1. Is this ECM "learning" a continuously ongoing process, or does it last for some initial period following reset?
2. In case it is not continuous, how to identify that learning curve is over or not yet?

I suppose whatever you do during learning would set the direction of tuning, inclined towards either performance or mileage. So, shouldn't one need to know that period and be consistent in what you are trying to program?

[santosh.s]

Dadu,

I understand that continuous monitoring and control of various parameters is the job of ECM. I think we are concerned about what is "remembered" in it's memory. I was wondering how long that learning happens and whether there is any definitive way to identify that. My concern is that, say, if one resets ECM and drives like a drag racer for some time (obviously to boost performance). However, if the learning has still not finished and the car is driven sedately for remaining duration of learning phase, then it may compensate for earlier heavy footed driving. Doesn't it?

[dadu]

There is no definitive way to know that but you can measure the parameters with the diagnostic tools and then compare yourself over time, see here

Originally Posted by santosh.s

Dadu,

I understand that continuous monitoring and control of various parameters is the job of ECM. I think we are concerned about what is "remembered" in it's memory. I was wondering how long that learning happens and whether there is any definitive way to identify that. My concern is that, say, if one resets ECM and drives like a drag racer for some time (obviously to boost performance). However, if the learning has still not finished and the car is driven sedately for remaining duration of learning phase, then it may compensate for earlier heavy footed driving. Doesn't it?

[santosh.s]

Thanks Dadu! I have already added OBD thread to my subscriptions, shall go through it at leisure.