[jsunma]

Does anyone here know what specifically happens mechanically when the car is awakened? Such as, when you unlock it or open any of the doors/trunk while it's asleep?

I'm sure that there are any number of things that happen electronically upon awakening, but that's not actually what I'm asking about. Rather, I'm most curious about what's going on when you hear the whirring electronic-motor sound. What is that? I ask because recently my whirring has been replaced sometimes by a squeak or more commonly a squeak mixed with the whirring.

(Yes, I'm sure someone is going to suggests rodents, and out here in the woods that's a good guess...but any others? )

I don't think it's the DTML pump as that's a different noise that the car makes after you turn it off.

Anyhow, I'm sure I have too much time on my hands if I'm worrying about noises my car makes when it's turned off and not moving...but, well, does anyone know what could be making the wake-up sounds?

[John 070]

Thought that's the fuel pump priming? I am the original owner of a 2007, and the car did not always do that. It came after a software upgrade. Back then, it was a weird concept and everyone was always making sure they had the latest/greatest. Seat belt butler falls off and doesn't hand the seatbelt? Instructions to dealership was do not replace any hardware, update the software lol

Today of course we accept that softare controls everything. Even a 7 yo knows to tape their cams on the school chromebook..

btw there's also a whirr under the hood and inside the dash, I never understood what that was, maybe that's what you mean.

[hassmaschine]

that's the fuel pump you're hearing. There's a anti-drain back valve to keep pressure in the line when it's off, but it's not a perfect seal. So when you unlock the car, if the pressure is low it will prime the pump. Otherwise, you'd have some really long cranks during startup because the fuel lines would be empty.

[ewicky]

Originally Posted by John 070

Thought that's the fuel pump priming? I am the original owner of a 2007, and the car did not always do that. It came after a software upgrade...

OMG that almost implies there's a way to code out the fuel pump prime!
I would love to explore that. Does anyone have experience with this?

[JonOhh]

It does it for a reason, I definitely wouldn't want to code it out. If it used to do it occasionally and now does it all the time, they probably just increased the threshold pressure under which it primes the pump upon wakeup.

The pump priming also does more than just increase fuel pressure in the low pressure line, it also serves to fill the LPFP bucket if it has drained since the car was last driven, making sure it's good to go as soon as the starter engages.

If they changed the behavior, it's probably for a reason.

[hassmaschine]

Originally Posted by ewicky

OMG that almost implies there's a way to code out the fuel pump prime!
I would love to explore that. Does anyone have experience with this?

It's not coding. It's part of the DME software. You have to know how to switch it off in the binary, and flash the DME.

[jsunma]

Well, that all makes sense about the fuel pump priming. I'm then guessing that the squeaking I'm hearing sometimes now is probably air...and that may have something to do with the venting system for the fuel tank. This perhaps tracks with the fact that the last several times I've filled up on fuel, the gas pump keeps shutting off before the tank is full.

Great. Something else to look into.

[ewicky]

Originally Posted by JonOhh

It does it for a reason, I definitely wouldn't want to code it out. If it used to do it occasionally and now does it all the time, they probably just increased the threshold pressure under which it primes the pump upon wakeup.

The pump priming also does more than just increase fuel pressure in the low pressure line, it also serves to fill the LPFP bucket if it has drained since the car was last driven, making sure it's good to go as soon as the starter engages.

If they changed the behavior, it's probably for a reason.

Sure, they did it for a reason. But was it a "good" reason? As in, would I have done the same thing for the same reason?

They also did something like this to "fix wastegate rattle" by opening them up and increasing turbo lag. It was slipped into a software update and not communicated to owners. The maneuver has since been exposed on these forums. Misguided warranty/service avoidance tactics are not the same values I would use to determine how I want my car configured.

They may very well have seen issues in only 0.1% of cars losing fuel prime, and yet, pushed the software to all cars just to avoid future service calls.

[hassmaschine]

It's to prevent long cranking and hard starts. Yes, it's better. Nearly every fuel injected car ever made does it.

[marvinstockman]

Every fuel injected vehicle, in the known and unknown universe, does a short, say 3 second, fuel pump prime when the car is first started. On most vehicles it is a tool to determine if the fuel pump is somewhat working.

[ewicky]

Originally Posted by hassmaschine

It's to prevent long cranking and hard starts. Yes, it's better. Nearly every fuel injected car ever made does it.

Originally Posted by marvinstockman

Every fuel injected vehicle, in the known and unknown universe, does a short, say 3 second, fuel pump prime when the car is first started. On most vehicles it is a tool to determine if the fuel pump is somewhat working.

As an alternative viewpoint, I'd like to point out that it's not uncommon for me to start my car without having woke it overnight and it starts right up without hesitation.
And both my previous fuel injected vehicles did not have a fuel pump prime before turning the key. So not only are you wrong, but I know it isn't necessary for my use case.

[jsunma]

Originally Posted by ewicky

As an alternative viewpoint, I'd like to point out that it's not uncommon for me to start my car without having woke it overnight and it starts right up without hesitation.

My car goes to sleep automatically and wakes up (making the noise that I was asking about at the top of the thread) as soon as I open any of the doors, the rear hatch, or the fuel flap. Not sure how you'd be in a position to start the car without having woken it up.

I do tend to agree with the folks here about pump priming. My 45 year old Volvo with Kjet injection primes the pump as well when you turn the key. (unless the fuel pump is broken or the electrical system is glitching...both of which are fairly regular occurrences on that car. )

[JonOhh]

Usually when people take the time and effort to pioneer some modification, or alter something for the first time, there's some obvious performance benefit or added convenience as the primary motivator.

I don't see how this is going to better any of our cars in any way, shape, or form. I do not understand why you want to turn it off, but to each our own. I respect others opinions.


Plus, don't you have a 335? Wouldn't you want to give that high pressure fuel pump everything it wants and needs instead of putting unnecessary strain on it? I believe the software update which altered the LPFP behavior quite literally mentioned that it is for the HPFP.

And yes. I don't understand how you apparently start the car without waking it up. Do you sleep in it? Do you leave the driver door open and the car unlocked? Do you tiptoe up to it as to not wake it from its restful sleep? Do you give it a big ass dose of melatonin? I don't understand.

[ewicky]

Originally Posted by jsunma

My car goes to sleep automatically and wakes up (making the noise that I was asking about at the top of the thread) as soon as I open any of the doors, the rear hatch, or the fuel flap. Not sure how you'd be in a position to start the car without having woken it up.

I do tend to agree with the folks here about pump priming. My 45 year old Volvo with Kjet injection primes the pump as well when you turn the key. (unless the fuel pump is broken or the electrical system is glitching...both of which are fairly regular occurrences on that car. )

I leave the keys in the ignition and the door cracked open. Each morning I sneak up on the car and start it without waking it first
Neither my E32 nor my A4/B5 primed the fuel pump before cranking.

[ewicky]

Originally Posted by JonOhh

Usually when people take the time and effort to pioneer some modification, or alter something for the first time, there's some obvious performance benefit or added convenience as the primary motivator.

I don't see how this is going to better any of our cars in any way, shape, or form. I do not understand why you want to turn it off, but to each our own. I respect others opinions.


Plus, don't you have a 335? Wouldn't you want to give that high pressure fuel pump everything it wants and needs instead of putting unnecessary strain on it? I believe the software update which altered the LPFP behavior quite literally mentioned that it is for the HPFP.

And yes. I don't understand how you apparently start the car without waking it up. Do you sleep in it? Do you leave the driver door open and the car unlocked? Do you tiptoe up to it as to not wake it from its restful sleep? Do you give it a big ass dose of melatonin? I don't understand.

I want to turn it off because it makes noise and is annoying, it appears to be completely unnecessary for normal usage. Friends/family often ask me why the car is making noises just for opening the door, and I have to explain it's because the car is "waking up" and it's a major eye roll. Certainly not luxurious.
And yes I sneak up on it and start it without waking it.
Unnecessary strain? It's a fuel pump, not a pillow.

[jsunma]

Well, indeed, to each their own. In my house, I'd get a whole lot more questions about leaving the keys in the ignition and the door open than I do about a little sound when getting into the car.

[hassmaschine]

Originally Posted by ewicky

As an alternative viewpoint, I'd like to point out that it's not uncommon for me to start my car without having woke it overnight and it starts right up without hesitation.
And both my previous fuel injected vehicles did not have a fuel pump prime before turning the key. So not only are you wrong, but I know it isn't necessary for my use case.

that's because it primed the pump without you noticing. it has nothing really to do with waking the car (for example, unlocking it, but not starting).

Just because you don't know it's happening, doesn't mean it's not important.

[hassmaschine]

Originally Posted by ewicky

I want to turn it off because it makes noise and is annoying, it appears to be completely unnecessary for normal usage. Friends/family often ask me why the car is making noises just for opening the door, and I have to explain it's because the car is "waking up" and it's a major eye roll. Certainly not luxurious.
And yes I sneak up on it and start it without waking it.
Unnecessary strain? It's a fuel pump, not a pillow.

well, learn how to program the DME then. Good luck.

[hassmaschine]

Originally Posted by ewicky

I leave the keys in the ignition and the door cracked open. Each morning I sneak up on the car and start it without waking it first
Neither my E32 nor my A4/B5 primed the fuel pump before cranking.

Yes they did. You just didn't know it was happening.

[Dave92N54]

Originally Posted by ewicky

I want to turn it off because it makes noise and is annoying, it appears to be completely unnecessary for normal usage. Friends/family often ask me why the car is making noises just for opening the door, and I have to explain it's because the car is "waking up" and it's a major eye roll. Certainly not luxurious.
And yes I sneak up on it and start it without waking it.
Unnecessary strain? It's a fuel pump, not a pillow.

If you care about your car making funny noises, not the car for you
Between the injectors, wastegates, evap valve, fuel pump priming & dmfw these things make enough noise to think a perfectly fine vehicle is falling apart. I live in an area where roughly 8/10 people have a diesel truck at home and I constantly get asked if my car is a diesel because of the injector noise. Disabling the fuel pump priming is absolutely not a good idea nor the solution here... unless for some odd reason you enjoy starving the hpfp

[ewicky]

Originally Posted by hassmaschine

Yes they did. You just didn't know it was happening.

No, they didn't. Nice try telling me something you don't know anything about, though. It looks good until you have literally no evidence to back it up, and I owned the cars and do. I knew it wasn't happening because on the incredibly rare occasion where the fuel system lost prime, I would have to prime it. I also could hear the fuel pump when it was on. And it wasn't before turning the key. Simple.

[ewicky]

Originally Posted by hassmaschine

well, learn how to program the DME then. Good luck.

Thanks. I already know how to program the DME as I have many times. It's not rocket science. I'll just have to find the bit(s) that switch this function.