Hi David,DHallworth wrote:Could it be an adaptive value that the old ECU needs to learn after having sensor changed?
I know on the Range Rover ECU's you clear the existing running config which causes it to run like a bag of spanners for a few miles, you take it for a run of mixed driving and it resets itself. According to the workshop manual, this is supposed to be done when replacing any of the engine sensors such as MAF, Lambda's, TPS, etc.
There's not a lot of detailed technical information on the MP7.0 that I can find, but according to what I've read unlike some ECU's none of the things it learns are retained when the battery is disconnected for at least 10 minutes. (In contrast to the gearbox ECU for example which has an eeprom that copies the auto adaptive tables from ram to eeprom 20 seconds after a key off event)
In other words it goes back to a blank slate with default values every time you take the battery off. When you start to drive it learns from the sensors and populates the long term fuel trim and knock retard tables. I'm not entirely sure whether the knock retard starts off "conservative" and creeps forward to a high octane map over a period of running, (I run 99 octane) or whether it starts off high and knocks it back if it detects a lot of pinging.
My ECU swapping suggest that it starts fully advanced after a reset and pulls the timing back quickly if it detects any pinging, (to adapt for low octane) as 9 times out of 10 a swapped or reset ECU starts off with maximum performance and then may intermittently tail off after some amount of driving.
There is a procedure listed in one of the technical documents "auto-adaption of the (mixture) richness" which says:
* Warm the engine up to over 80 degrees
* Check there are no stored fault codes
* Turn ignition off then on again
* Start engine without pressing accelerator
* Let the engine idle for 5 minutes without pressing the accelerator
It also states that clearing the fault codes will not reset the mixture adaption. (but disconnecting the battery will)
I've tried this procedure before and didn't notice anything in particular - all its doing is giving enough time for the oxygen sensor to warm up so that it can learn the long term fuel trim for a stoichiometric ratio.
Given that battery off means a reset to defaults I've almost always found that the engine runs best immediately after the reset and deteriorates over time, so it doesn't seem to need any special procedure like you mention for the Range Rover.
On Sunday I literally went for a 20 minute drive on your ECU - perfect performance as it had been all week, came home, swapped the ECU's, immediately went out again for another 20 minute drive with the engine still warmed up - perfect performance immediately. (But will it last more than a few days... I don't know yet)