To Idle or not to Idle, that is the ?

[NewfieDan]

I used to own a Dodge with a Cummins. When it was really cold out I could see fuel dilution being a problem with extended idle. It would kick up to a high idle to help keep itself warm. I know it can also make the DPF regen more if you idle a lot. Gas engine? I just don't see it being a problem.

In my mind the problem with a lot of idle is you aren't getting any kind of fuel mileage. 0 mpg. That said an engine at idle isn't using a lot of fuel.

I have a Dodge with a Cummins. Have had this truck for almost 14yrs, and have never had a problem with fuel dilution. Even when idling in extreme cold.

As for idling a gas engine, just how long would it take to warm up the rings inside a running engine. At most they are fractions of an ounce and so would not take very much heat energy to warm up and expand to form a tight seal. If the rings are put in properly, with their joints on opposite sides of the cylinder, gas running down the cylinder wall would be a non-issue.

 

[Oldpath05]

"gas running down the cylinder wall would be a non-issue."<<<<I can only see this possibly happening in the good ole days with caberaterated cars, with manual/auto choke at first start up, but in todays computer operated fuel delivery systems, dont see how it's possible and dont see how it can be proven. I dont think race car drivers are worried about gas running down the cylinders if they was, they'ed roll their dragster out to the start line then start it up when the light turned green.

 

[Oldpath05]

I used to own a Dodge with a Cummins. When it was really cold out I could see fuel dilution being a problem with extended idle. It would kick up to a high idle to help keep itself warm. I know it can also make the DPF regen more if you idle a lot. Gas engine? I just don't see it being a problem.

In my mind the problem with a lot of idle is you aren't getting any kind of fuel mileage. 0 mpg. That said an engine at idle isn't using a lot of fuel.

What is diesel fuel dilution?

 

[Snobdds]

"gas running down the cylinder wall would be a non-issue."<<<<I can only see this possibly happening in the good ole days with caberaterated cars, with manual/auto choke at first start up, but in todays computer operated fuel delivery systems, dont see how it's possible and dont see how it can be proven. I dont think race car drivers are worried about gas running down the cylinders if they was, they'ed roll their dragster out to the start line then start it up when the light turned green.

It happens on gas motors with direct injection and high pressure fuel pumps. They operate at pressures in excess of 20,000 psi. Those high pressures push the gas pass the rings.

 

[Diamondpilot]

I once idled my truck for 12 hours with a extended exhaust pipe into a Mole Trail.

It killed them off an only used about 4 gallons of gas.

 

[MossRoad]

I once idled my truck for 12 hours with a extended exhaust pipe into a Mole Trail.

It killed them off an only used about 4 gallons of gas.

No bodies no kill.... :laughing:

I have an ongoing thing with moles....

 

[dodge man]

I should have said fuel dilution of your oil. Diesels are compression fired. They rely on heat and compression to run. When it's really cold out they lack the heat so in theory all the fuel might not burn. This fuel can wash down the cylinder walls a wear them out and/or run past the rings into the oil. Does this happen in the real world? Not usually. A bad injector can cause it or some engines can have this problem when the DPF regent.

I guess I'm lost as to why a direct injection gas engine would have this problem? So what if they are high pressure. I only see it as a problem if they are injecting to much fuel.

 

[MossRoad]

I should have said fuel dilution of your oil. Diesels are compression fired. They rely on heat and compression to run. When it's really cold out they lack the heat so in theory all the fuel might not burn. This fuel can wash down the cylinder walls a wear them out and/or run past the rings into the oil. Does this happen in the real world? Not usually. A bad injector can cause it or some engines can have this problem when the DPF regent.

I guess I'm lost as to why a direct injection gas engine would have this problem? So what if they are high pressure. I only see it as a problem if they are injecting to much fuel.

We have a 2013 Impala with the 3.6L LFX engine that has GDI. Here's an animation of how the fuel is delivered. It is sprayed in during the intake stroke, when the intake valves are open. So the high pressure of the fuel injection has NO effect on the pressure inside the cylinder, because the intake valves are open and the piston is on the downstroke. I'm guessing its the same on a diesel. I just don't see how high pressure direct injection can force fuel past the rings because there's no pressure until well after the fuel stops spraying and the valves are closed.

Could the compression stroke force fuel past the rings? Sure. But not the fuel injection system. Anyone have a diesel animation?

 

[Btown]

I let my 99 350 warm up as well. maybee not 5m, but some for sure. Even if it's only starting it, then walking my cooler to the truck, and then walking the trash to the road and grabbing my newspaper and walking back to the truck. Just anything other than hopping in, starting, and slamming it into gear and flooring the throttle and tearing off on a stone cold engine.

If it's really cold out ( below 10 degrees F) you can step on it all you want with those 7.3's, but it won't go anywhere fast till it warms up a little. My understanding is fuel dilution is mostly a problem with the newer 2008+ engines, so older engines really don't have this problem. When you run bio-diesel mix fuels in newer engines you really have to look out for fuel dilution. biodiesel will not evaporate from the oil like diesel can one warmed up.

 

[KubotainNH]

Here remote starters are common. I have a 99 Jeep and a 00 Honda van, I installed identical remote starters (this brand allows the keyfob to start either) in both of them when I got them maybe 12 or 13 years ago. The starters are used almost everyday in winter and sometimes in summer on hot days for A/C. The Jeep has 153k and the Honda is over 190k. Neither burn oil and both run very well for their age and mileage. If I didn't have remote start for my Jeep that old 4.0 would never give me heat when it's 20 degrees here. Screw that, I'll remote start it.