Rough idle when refueling? Z4M, S54

[filtercoffee]

Hi, I've noticed that if I leave the engine on while refueling, the engine sometimes misfires. The idle is normally 100% smooth, it's only when filling gas that it stumbles a bit. Does this happen to anyone else?

[86Zed]

Why are you leaving the engine on while refueling?

I'll add to the above comment - if turning the car off stops this weird issue it is a no brainer...

[Reborn_]

I can’t say I’ve ever done this. In any vehicle.

[filtercoffee]

I should've anticipated these responses :P

Of course I will be shutting my car off to refuel in the future given the misfire issue, but I was wondering if the symptoms indicate a mechanical issue, or if it's normal.

[Salty Dog]

Originally Posted by filtercoffee

I should've anticipated these responses :P

Of course I will be shutting my car off to refuel in the future given the misfire issue, but I was wondering if the symptoms indicate a mechanical issue, or if it's normal.

The gas cap being removed effects the fuel system, if you notice the gas cap actually creates a bit of vacuum on the system. You'll hear a sound if you listen when you remove the gas cap of air being sucked into the system.

[racerbruce]

No judgement here, just important info from the American Petroleum Institute:

Here Are Additional Consumer Refueling Safety Guidelines That Will Help Keep You And Your Family Safe When Refueling Your Vehicle Or Filling Up Gasoline Storage Containers:

-Turn off your vehicle engine.
-Put your vehicle in park and/or set the emergency brake.
-Disable or turn off any auxiliary sources of ignition such as a camper or trailer heater, cooking units, or pilot lights.
-Do not smoke, light matches or lighters while refueling at the pump or when using gasoline anywhere else.
-Use only the refueling latch provided on the gasoline dispenser nozzle.
-Never jam the refueling latch on the nozzle open.
-Do not re-enter your vehicle during refueling.
-If you cannot avoid re-entering your vehicle, discharge any static build-up BEFORE reaching for the nozzle by touching something metal with a bare hand -- such as the vehicle door -- away from the nozzle.
-In the unlikely event a static-caused fire occurs when refueling, leave the nozzle in the fill pipe and back away from the vehicle.
-Notify the station attendant immediately.

[filtercoffee]

Just to play devil's advocate, why would running your engine while refueling be considered unsafe? Obviously the fueling system doesn't like it but I don't see the safety hazard. Maybe someone can enlighten me.

[Salty Dog]

Originally Posted by filtercoffee

Just to play devil's advocate, why would running your engine while refueling be considered unsafe? Obviously the fueling system doesn't like it but I don't see the safety hazard. Maybe someone can enlighten me.

There is a very very slight risk of fire.

[racerbruce]

US gas station fire stats....

https://www.hud.gov/sites/documents/STATIONS.PDF

[pungo]

Originally Posted by filtercoffee

Just to play devil's advocate, why would running your engine while refueling be considered unsafe? Obviously the fueling system doesn't like it but I don't see the safety hazard. Maybe someone can enlighten me.

It's unsafe because someone can hop in a take off with your nice car...


Or someone kicks your a$$ because they feel you're endangering their life.
Or there's an explosion

Besides, it's the law, though probably not enforced much.

[Kazansky]

Originally Posted by filtercoffee

Just to play devil's advocate, why would running your engine while refueling be considered unsafe? Obviously the fueling system doesn't like it but I don't see the safety hazard. Maybe someone can enlighten me.

Originally Posted by filtercoffee

Just to play devil's advocate, why would running your engine while refueling be considered unsafe? Obviously the fueling system doesn't like it but I don't see the safety hazard. Maybe someone can enlighten me.

Can't believe you actually do this. This is a common practice to STOP the engine while refueling. Read sign on your gas pump.

[Willy Sea]

Originally Posted by Kazansky

Can't believe you actually do this. This is a common practice to STOP the engine while refueling. Read sign on your gas pump.

Because exhaust hot............

[filtercoffee]

Willy Sea, Exhaust hot even after you turn off the car

Kazansky, that point has already been made. I wanted to keep this to a technical discussion about the fueling system. It's also OK to discuss the risks of refueling with a car on.

No one has mentioned the actual mechanism by which a running engine would ignite while refueling. The only source of spark in a running car should be inside the combustion chamber. If anything, starting/stopping cars might trigger relays e.g. for the starter motor that arc in the engine bay near the presence of gasoline fumes.

Also I don't do this when I'm alone. I sometimes do it when I have a passenger in the car and it's cold out. I sometimes do it at full service pumps like in New Jersey. I will no longer be doing it because of the rough idle issue. I know that plenty of people in the NY tri-state area do this and gas stations are not constantly catching fire because of it.

[Salty Dog]

Originally Posted by filtercoffee

Willy Sea, Exhaust hot even after you turn off the car

Kazansky, that point has already been made. I wanted to keep this to a technical discussion about the fueling system. It's also OK to discuss the risks of refueling with a car on.

No one has mentioned the actual mechanism by which a running engine would ignite while refueling. The only source of spark in a running car should be inside the combustion chamber. If anything, starting/stopping cars might trigger relays that arc in the presence of gasoline fumes.

So the only source of ignition isn't the combustion chamber....backfires can occur. Accidental ignition of fuel fumes. During the refuelling procedure the fumes or vapour from the fuel being pumped can accumulate on the ground level near your car. ... These scenarios or potential causes of accidental fires at the fuel pumps can be avoided by switching off the vehicle engines and accessory power sources.

Of course a very slim chance of this happening, but really who wants to risk a car fire next to the gas pumps. Safety Third.

[86Zed]

Originally Posted by filtercoffee

Also I don't do this when I'm alone. I sometimes do it when I have a passenger in the car and it's cold out. I sometimes do it at full service pumps like in New Jersey.

I cannot recall an instance here in Minnesota where I saw someone idling while refueling - I wager it is as cold as NY if not colder here...

While the risk may be exaggerated, why roll the dice?

[SD ///M4]

Originally Posted by Kazansky

Can't believe you actually do this. This is a common practice to STOP the engine while refueling. Read sign on your gas pump.

Apparently, this is another example of common sense not being so common, especially in NY.

I lived in Michigan for the first 38 years of my life, and it used to get pretty damn frigid there, but I never saw anyone leaving their car running while refueling.

This seems like the kind of story where someone has been doing something stupid their whole life, not paying attention to how normal people do it, and then when they find out that no one else does it like they do, they get embarrassed and make excuses why their method is the correct way, not the stupid way.

[filtercoffee]

Why did you turn my ignorance into an attack on the people of NY? That doesn't advance this discussion at all.

Again, exhaust pipes remain hot even after you turn off the car, and starting the car actually may create sparks due to relays + the starter motor. Backfire would also be limited to your intake and exhaust manifold. Let's please use our logic instead of saying things like "I can't believe you do this". Static electricity seems like a bigger risk and that has no relation to the car being on. The only potential risk I can see is if refueling causes your fuel pump to get air in the fuel lines and the spark in the combustion chamber ignited the air/fuel in the fuel lines. However cars have to be designed to prevent this from happening or else cars would be exploding when you go over bumps that would cause your fuel pump to pump air.

Yes, there's signage and best practices and I acknowledge all of that. So you can stop making your same points. They are redundant. I just wanted to examine this further technically.

[filtercoffee]

Another odd thing I've noticed. At full service stations, I've never had the gas-filling person tell me to turn the car off. This is telling.

[racerbruce]

Originally Posted by filtercoffee

Another odd thing I've noticed. At full service stations, I've never had the gas-filling person tell me to turn the car off. This is telling.

Advise your insurance agent you prefer refueling while your engine is running....

https://www.google.com/search?rlz=1C...eRBIQ1HsjO3tUM

[Salty Dog]

Originally Posted by filtercoffee

Another odd thing I've noticed. At full service stations, I've never had the gas-filling person tell me to turn the car off. This is telling.

Funny, I've heard the attendants come on the PA system and tell people to shut their car off.

[filtercoffee]

Originally Posted by racerbruce

https://www.google.com/search?rlz=1C...eRBIQ1HsjO3tUM

Originally Posted by filtercoffee

Yes, there's signage and best practices and I acknowledge all of that. So you can stop making your same points. They are redundant. I just wanted to examine this further technically.

haha

https://www.google.com/search?q=imag...Kvr40IstfGYkYM

and

https://www.google.com/search?q=55+m..._ZaBZJiFf2OaFM

and

https://www.google.com/search?q=turn...xcOL2LVL3kokGM

[SD ///M4]

Originally Posted by filtercoffee

Why did you turn my ignorance into an attack on the people of NY? That doesn't advance this discussion at all.

Again, exhaust pipes remain hot even after you turn off the car, and starting the car actually may create sparks due to relays + the starter motor. Backfire would also be limited to your intake and exhaust manifold. Let's please use our logic instead of saying things like "I can't believe you do this". Static electricity seems like a bigger risk and that has no relation to the car being on. The only potential risk I can see is if refueling causes your fuel pump to get air in the fuel lines and the spark in the combustion chamber ignited the air/fuel in the fuel lines. However cars have to be designed to prevent this from happening or else cars would be exploding when you go over bumps that would cause your fuel pump to pump air.

Yes, there's signage and best practices and I acknowledge all of that. So you can stop making your same points. They are redundant. I just wanted to examine this further technically.

Originally Posted by SD ///M4

This seems like the kind of story where someone has been doing something stupid their whole life, not paying attention to how normal people do it, and then when they find out that no one else does it like they do, they get embarrassed and make excuses why their method is the correct way, not the stupid way.

OK, enough with all of the common sense advice to turn off your engine while refueling. That point has been made and received loud and clear by the OP.

Instead, let's pursue this aspect a little more...