Talk Morgan Forums Morgan Sports Cars Classic Morgans (pre-CX) Battery Removal and ECU

On the first service from new on my Plus 4 (back in 2016) a factory flash upgrade was carried out (or installed - not sure what the correct term is) on (or to) the ECU. I'm just about to replace the vehicle battery and remembered reading somewhere (probably in Dave Welling's book) that disconnecting the battery can return the ECU to its factory settings. Does anyone know if this wipes out the flash upgrade or just the data it's gathered since the upgrade was carried out? Thanks.

I think (stress think) the ecu flash will be fine but what will be reset are any specific diving tendencies that it will have learnt wile you have been driving. For example the rpm that you usually change gear at, how hard you brake, how much you press the accelerator coming out of a corner, etc.

Incidentally the ‘cheat device’ fitted to many cars to trick the economy and emission figures isn’t actually a thing at all, it’s a software ecu mode that trips in when the ecu detects the car is being put through the testing cycle. The ecu ‘learns’ it’s being tested and alters its parameters to be optimal for the test.

Kevin the flash should be fine but if you are worried you can either keep a battery conditioner connected or a special back up battery. If you are really worried you can borrow my ctek

I think a factory download is different as they can access the ecu programable chip but if you had a performance download by some non associated company that may well be lost. Don't worry about the memory stored as to the way you drive, it will quickly update when you get the car back on the road. that memory is constantly updating itself.

Thanks John. I’ve got a CTek but I think Sewin’s reply is pretty reassuring.

I use the ctek on my tin top battery changes as it saves the phone , sat nav and radio settings according to VW

ECU flashes Kevin upgrade the firmware held by an EPROM chip within the ECU by overwriting the code it previously held. Since the EPROM represents non-volatile memory the new firmware code is permanently locked (burnt) into it, until perhaps another firmware update/flash that is. Much the same on your PC, smart phone and many other electronic devices nowadays where upgrades may be offered to correct previous programming errors or add new features.

What will be lost by a battery disconnection is the adaptive mapping for the engine, held in RAM within the ECU, and continually updated to tune your particular engine. It will simply adopt the base map in the firmware on battery re-connection with adaptive mapping re-learnt in short order. No need to mess around with temporary power sources therefore. Note some modern cars may require a charge profile reset after fitting a new battery but not your Morgan

Thanks Richard. Incredibly I understood all that!

If you have a radio/CD player, it might require the original code to operate it if the battery has been disconnected. I've had a few cars with this 'feature'.