Last week I had to replace the original nine and a half year old battery on the Mondeo. Starting had become more laboured until, one morning after a frost, the battery couldn't turn the engine over at all.
The car seemed to go better with the new battery and I thought it must be psychological, but I've just filled the tank again and achieved 40.12 mpg on the last tankful in mixed motoring conditions. Sounds daft, I know, but could a new battery possibly improve engine performance?
|
It's much more likely that during the disconnection the adaptive learning memories of the engine ECU were cleared and reset to zero.
Number_Cruncher
|
" adaptive learning memories of the engine ECU were cleared and reset to zero."
On a 9.5 year old car ? Where they that sophisticated then ?
|
>>On a 9.5 year old car ?...
Indeed they were - along with exotic features like Kalman filtering based misfire detection algorithms - even on some quite mundane applications. Rover 214s with the MEMS system were adaptive from the early 90's.
Number_Cruncher
|
|
|
|
It's much more likely that during the disconnection the adaptive learning memories of the engine ECU were cleared and reset to zero.>>
Blimey, does this mean that it's been learning bad habits over the last nine and a half years? In fact, would there be any benefit in disconnecting the battery for 5 minutes every year or so .... to free its mind?
I should add, the cars average mpg is about 34.
|
"bad habits over the last nine and a half years"
I shudder to think what habits my cars pick up on....at least they'll be non smokers.
|
|
|
|
|
Last week I had to replace the original nine and a half year old battery on the Mondeo. Starting had become more laboured until, one morning after a frost, the battery couldn't turn the engine over at all. The car seemed to go better with the new battery and I thought it must be psychological, but I've just filled the tank again and achieved 40.12 mpg on the last tankful in mixed motoring conditions. Sounds daft, I know, but could a new battery possibly improve engine performance?
A 'flattened' battery makes the alternator work harder. The effort of charging a battery that is 'off it's best' may well increase the fuel consumption & make the engine less 'perky' .
Putting a good battery in place of one that old will make the engine work less hard. So yes it IS possible
|
A 'flattened' battery makes the alternator work harder. The effort of charging a battery that is 'off it's best' may well increase the fuel consumption & make the engine less 'perky' . Putting a good battery in place of one that old will make the engine work less hard. So yes it IS possible
A bit like having one's aircon on. It makes the engine work harder and therefore increases fuel consumption
|
There's a company that makes a gadget called "Alterpower", if I remember right it's an electronic clutch mechanism for alternators and a bit of software that controls the clutch. When you hit full throttle, it disengages the alternator so the pulley freewheels.
Supposed to save between 8 and 10 bhp, they say.
|
|
my car has a limp/saftey mode for when the battery gets really low , it dumps in extra fuel to safegaurd the engine against low pump performance etc
|
|
|
I think we ought to be told more about these adaptive learning memories. My car (1993) has a "Lambda" light that comes on if a little black box detects any of a many faults that might develop in a variety of sensors. Disconnecting and then reconnecting the battery is one way of resetting this function, but only if the underlying fault has been rectified.
Waino's car seems to have a much more sophisticated memory, which can learn and adapt to circumstances that might not necessarily have been faults, simply a less than optimum setting. It seems to me curious that the system can on the one hand be so clever, as to learn all this, yet at the same time apparently have no mechanism for realising that it has accumulated a load of bum info, and doggedly go on for nine years getting more gaga. And yet a simple cure was at hand all the time - ECT in the form of briefly pulling its plug out.
Please explain more, N-C.
|
|
What does it return the memory to, it's original factory settings or any updates that may have been introduced during servicing by the dealer?
|
|
Most modern ECU's turn off the A/c when you go to wide open throttle and only turn it back on as you ease off the accelerator.
|
Most modern ECU's turn off the A/c when you go to wide open throttle and only turn it back on as you ease off the accelerator.
I'm going to have to try this now
|
|
|
|
Waino's car seems to have ........ accumulated a load of bum info, and doggedly go on for nine
years getting more gaga.>>
Oh dear, don't they say that one's car tends to reflect one's personality? ..... mmmmm ;-(
We have two perfectly feasable theories for the OP observation - the ECU's accumulated stupidity (I haven't a clue how these things operate) and ffidrac's explanation whereby the battery has gradually become less effective causing the alternator/engine to work harder - which I find easier to understand. Less/more 'perky' describes the situation perfectly.
In the case of the latter, I wonder if there's an identifiable point where it becomes economical to chuck an old battery away [in an environmentally acceptible manner!] and replace it with a young fresh one.
|
|
Is someone here seriously suggesting that ECUs adapt to the style in which the car is driven...and therefore perform steadily worse until the adaptations are wiped away and they can revert to factory settings? And if so, doesn't anyone else think this is absurd?
|
|
If the battery is dud it was probably slightly screwing up the values held in the ECU...a nie steady power source from a new battery might mean everything stays as it should.
|
|
My Passat gets very confused whenever I disconnect the battery (as you have to to avoid the poxy water leaks........). The ECU forgets the throttle body settings and the car runs like a dog. In theory, it's supposed to relearn them over time though it didn't seem to for a few days after the first time I did it. Now I use VAG-COM and a laptop and it does the trick. Still, I can't help feeling that it's very poor design. It can remember other non-volatile data like the odometer reading so why not this?
|
|
|
|
>>We have two perfectly feasable theories...
Yes, if the duff battery were drawing a lot of current from the alternator, this would reduce the available performance from the engine - possibly by a significant amount.
The adaptive settings *should* adapt the factory settings to give better performance and economy - for example, under load, the ignition timing for each cyclinder will be varied a little, and the change in crank speed during that firing stroke measured and stored - then, the adaptive map will tend towards the setting which gives the best crank acceleration - subject to the continued silence of the knock sensor!
As different people drive the cars differently, the areas (of speed, load, temperature, etc, etc) where these maps are updated the most will vary. The tricky thing to get right is how to update the adaptive memories - how much weight should be given to the previous settings already in the memory compared with the most recent data just obtained? How far from base settings should the adaptive mapping be allowed to get?
Number_Cruncher
|
|
I believe that a combination of both NC's points could make it a very noticable difference, IIRC the battery would have had to be disconnected for around 30mins for the adpative memory to be wiped though.
|
|
|
|
|
|
|
|
