It's for this reason that, in some quarters I've heard of[1], one of the questions asked when you misfuel a car is "have you opened the door?" If negative they can get away with a drain, otherwise they insist on replacing the whole HP side too.
FWIW, with regard to system priming, my E46 320d will run the LP pump for a period of time when the ignition's switched to pos II. Repeat as necessary to bleed the system.
[1] Main dealers covering their backs for the sake of warrantees.
A scan tool can read the fuel pump delivery rate, and the actual rpm of the fuel pump, as well as the speed the pump *should* be running at.
Everything about these cars is over complex, IMHO.
Here is an example:
There is a sensor that is bolted to the battery negative terminal which measures battery voltage and temperature every 25 milli-seconds, even when the car is asleep. It even keeps a record of the results, too, for driver use profile. I believe it is to be able to blame the driver for flat batteries rather than replace them under warranty.
It seems from what I read now, that BMW knows that the AGM battery chemistry is not ideal for engine Stop-Start systems (1), and has now invested in the company making 'lead-carbon' chemistry batteries.
(1) Neither of our cars utilise Stop-Start technology.
David
When turning on the ignition on this car, all the modules wake up, and there is a lot going on that makes a fair bit of noise, such as the ventilation system flap motors, and it is difficult to identify one noise from another. I suppose if I lifted the rear seat squab before turning on the ignition (push the start button *without* pressing the brake pedal), I might be able to tell, especially with the stethoscope.
David
It's likely then that this vehicle turns the alternator off during daytime running whenever possible. It's a fuel-saving technique.
The profile is to have a record of battery performance in order to determine when the alternator can go off-load.
Chris
Sort of, yes. This device gives data to the engine management to calculate battery charge, aging and capacity for the charge rate. Also, it allows the management to completely shut the car's systems down to enable enough charge remaining in the battery to start the engine after a long inactive period.
When a battery is replaced, the charging map has to be changed to accommodate the new battery's performance. The management control requires that it is notified of a new battery.
Not from what the a tech at the dealership told me last week. BMW were spending a lot replacing good batteries and alternators. There is now a special series of tests to be run before battery / alternator replacement using a £1200 tester.
I have written before about how disconcerting it can be watching the system voltage drop to 11.7 volts or so whilst on a longer motorway trip. If I turn on the side-lights, then the system stays at 13.7 volts, and
14.6 volts on the over-run (if the engine's revs are high enough).One of my scanners shows that although the voltage falls to 11.7 volts, the alternator can still be at 18% load....
David
Sort of, yes. This device gives data to the engine management to calculate battery charge, aging and capacity for the charge rate. Also, it allows the management to completely shut the car's systems down to enable enough charge remaining in the battery to start the engine after a long inactive period.
When a battery is replaced, the charging map has to be changed to accommodate the new battery's performance. The management control requires that it is notified of a new battery.
Not from what the a tech at the dealership told me last week. BMW were spending a lot replacing good batteries and alternators. There is now a special series of tests to be run before battery / alternator replacement using a £1200 tester.
I have written before about how disconcerting it can be watching the system voltage drop to 11.7 volts or so whilst on a longer motorway trip. If I turn on the side-lights, then the system stays at 13.7 volts, and
14.6 volts on the over-run (if the engine's revs are high enough).One of my scanners shows that although the voltage falls to 11.7 volts, the alternator can still be at 18% load....
David
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