arghh..cutting out... (possibly not stepper motor)

[CJ]

It took about 100km of driving and it was perfect from then on. It's just the ECU learning the new battery and whats required to find the correct idle. It should pass in a day or two and be 100% perfect again.

It shouldn't normally take that much in the way of driving for the ECU to re-learn the engines idling characteristics, once the car is idled for 15 mins after reconnection, 30 kms max should be sufficient under normal operating circumstances.

CJ

[iwannafto]

Nice one...I thought I was going to be into more expense!

[mcgon1979]

30 kms max should be sufficient under normal operating circumstances.
CJ

yeah I'd believe that alright. I was doing motorway runs though, so probably 15 mins in town traffic would have had the same effect.

[mivecmad27]

i'm not convinced its ecu adaption as an ecu is like a computer processor,granted most of these control units are over 10 years old but they shouldn't take days to adapt to conditions,and if so would re-occur wih every car that got its battery changed

[CJ]

i'm not convinced its ecu adaption as an ecu is like a computer processor

An ECU is far more that a CPU, yes theres a processing unit in there but theres also EPROM (maps) and RAM (sensor tolerances). The latter can only be populated by a 'learning' process - the ECU tracks the tolerance changes of the sensors and actuators in the engine i.e. the position of the stepper motor at idle with the a/c on and off, injector gain values etc.

If the method I outlined above is followed, the learning process is reduced significantly. As I mentioned, long learning periods are often indicative of sensors or actuators that are on the way out or need maintanence, particularly so in the case of the stepper motor.

CJ

[mivecmad27]

I know that an ecu is more than just a cpu,i was just using it as a simplified example.

[fatboyfat7]

Disconnected my perfectly strong battery last night to reset the ECU. Reconnected it and suffering these problems so I guess it can affect the same battery... Although as per CJ's post above, the reason I tried to reset the ECU was to test whether or not my Throttle Position Centre was faulty! Guess Im in no mans land!