[2010 M Sport]

Does anyone know the cause of a gas smell coming thru the a/c vents at start-up? I'm thinking it's a leaky injector, but has anyone else had this issue? Car is throwing cylinder#5 misfire code. Thx

[JDrago1926]

Originally Posted by 2010 M Sport

Does anyone know the cause of a gas smell coming thru the a/c vents at start-up? I'm thinking it's a leaky injector, but has anyone else had this issue? Car is throwing cylinder#5 misfire code. Thx

Seems like cylinder 5 always has misfire issues lol same with mine, ended up being an injector. However, I never got any gas smell through the A/C

[2010 M Sport]

Anyone?

[MilehighM3]

Are you sure it's gas and not refrigerant? Evaporator makes a lot more sense than a leaking injector. Injectors leak into the cylinders, not externally unless something was improperly installed or torqued previously.

[2010 M Sport]

Originally Posted by MilehighM3

Are you sure it's gas and not refrigerant? Evaporator makes a lot more sense than a leaking injector. Injectors leak into the cylinders, not externally unless something was improperly installed or torqued previously.

Definitely a smell of unburned gas. I haven't had the injectors out-so...When you say torqued- to tight or loose? Don't see how that would have happened either.

[Sfvalley135i]

do you have the bms cowl filters?

[2010 M Sport]

Originally Posted by Sfvalley135i

do you have the bms cowl filters?

No- the M3 cowl set up.

[MilehighM3]

Originally Posted by 2010 M Sport

Definitely a smell of unburned gas. I haven't had the injectors out-so...When you say torqued- to tight or loose? Don't see how that would have happened either.

Has your dealer replaced them, a high pressure pump, low pressure sensor etc? If not then perhaps an exhaust leak being drawn into the blower motor.

[2010 M Sport]

Originally Posted by MilehighM3

Has your dealer replaced them, a high pressure pump, low pressure sensor etc? If not then perhaps an exhaust leak being drawn into the blower motor.

Could it be the clamps where the dp's meet the turbo? Maybe not seated all the way? How would that cause a gas smell at start up only?

[MilehighM3]

Originally Posted by 2010 M Sport

Could it be the clamps where the dp's meet the turbo? Maybe not seated all the way? How would that cause a gas smell at start up only?

I'm reaching here, but perhaps the unburned fuel in the exhaust when the engine is shut off is collected by the cabin filters if you have an exhaust leak. That or your auto recirculate (if used) doesn't get a chance to activate the recirculate quick enough? The fuel pressure is constant at idle, regardless of engine temp, and increases under load/boost. If anything it would be worse when driving, not on initial startup if it were a fuel leak.

I'm still thinking it's refrigerant and you have an evaporator leak, but that's just because I've replaced a lot of them for leaking. Same complaint every time, smell from the vents on initial startup.

[2010 M Sport]

Originally Posted by MilehighM3

I'm reaching here, but perhaps the unburned fuel in the exhaust when the engine is shut off is collected by the cabin filters if you have an exhaust leak. That or your auto recirculate (if used) doesn't get a chance to activate the recirculate quick enough? The fuel pressure is constant at idle, regardless of engine temp, and increases under load/boost. If anything it would be worse when driving, not on initial startup if it were a fuel leak.

I'm still thinking it's refrigerant and you have an evaporator leak, but that's just because I've replaced a lot of them for leaking. Same complaint every time, smell from the vents on initial startup.

Do they smell similar?

[MilehighM3]

Yes refrigerant is commonly mistaken for fuel. Take it in and have it looked at, let us know what the diagnosis is.

[brg4913]

Make sure your cabin filter box is sealed properly. You could be drawing fumes through there. I have an e90 n54 with a leaky injector and when it is parked in the garage I can smell gas fumes.

[BlackBB6]

You can eliminate some of the guess work by checking the #5 spark plug, see if it's black and smells like gas.

[Jeff@TopGearSolutions]

Originally Posted by BlackBB6

You can eliminate some of the guess work by checking the #5 spark plug, see if it's black and smells like gas.

I'm surprised nobody has said this until now...

Guys, your spark plugs can tell you a lot about what's going on... check your spark plugs for fouling and that would be an indication of a leaky injector.

[2010 M Sport]

Originally Posted by Jeff@TopGearSolutions

I'm surprised nobody has said this until now...

Guys, your spark plugs can tell you a lot about what's going on... check your spark plugs for fouling and that would be an indication of a leaky injector.

But if the plug looks normal? Can it be LPFP? or HPFP? I will log!