Myths of Idling

I always let my car warm up (by idling), in spite of what is stated by the Fleet Target Newsletter.

Thoughts?

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Myths of Idling

Myth #1 - The engine should be warmed up before driving.

True, the engine must be warmed up, but idling is not an effective way to warm up your vehicle, even in cold weather. The best way to do this is by driving the vehicle. With today's modern engines, and the advent of electronic engines, you need no more than about 30 seconds of idling before driving away, even on the coldest winter days.

Myth #2 - Idling is good for your engine.

Excessive idling can actually damage your engine components, including cylinders, spark plugs, and exhaust systems. An idling engine is not operating at its peak temperature, which means that fuel does not undergo complete combustion. This leaves fuel residue that can condense on cylinder walls, where they can contaminate the oil and damage parts of the engine. For example, fuel residues are often deposited on spark plugs. As you spend more time idling, the average temperature of the spark plug drops. This makes the plug get dirty more quickly, which increases fuel consumption by four to five percent. Excessive idling also lets water condense in the vehicle's exhaust, leading to corrosion and can reduce the life of the exhaust system.

Myth #3 - Shutting off and restarting your vehicle is hard on the engine.

Frequently restarting has little impact on engine components like the battery and the starter motor. Component wear caused by restarting the engine is estimated to add $10 per year to the cost of driving, money likely to be saved many times over due to fuel savings.

Myth #4 - Shutting off and restarting your vehicle uses more gas than if you leave it running.

The bottom line is that over 10 seconds of idling uses more fuel than restarting the engine. As a rule of thumb, if you are going to stop for 10 seconds or more - except in traffic - turn off the engine. You'll save money, and you won't produce harmful Carbon Dioxide, the leading greenhouse gas.

This points to the danger of actually starting your car

Excess idling is not necessarily a good thing, but shutting off your engine for every 10 second stop is a bad idea.

This points to the danger of actually starting your car

 

Excess idling is not necessarily a good thing, but shutting off your engine for every 10 second stop is a bad idea.

- except in traffic -

I always wait until the 0:01 on my trip clock before putting it in gear, regardless of outside temp. This gives me time to check mirrors, dust the dash, tweak the seat position, change the radio station, etc...

I hate to idle the car more than 5-10 minutes unless it is extremely cold/icy out and I need to let the wiper heaters do their magic. Now that I have a garage I expect this happen much less frequently.

Also for a Turbo car you need to let the car idle down for a little to bring cooler oil to the turbo. ie Turbo Timer

thats not the case for our cars (unless youve been tracking it for an hour just beforehand)

F-WDC, we have a oil and water cooled turbo that actually keeps the coolant flowing through the turbo even after the engine has been shutoff. This cools the turbo without the need to keep it running or the fear of cooked oil.

- except in traffic -

I don't see why that should matter - if idling is bad then it is bad

Not for a water and oil cooled turboed car, like ours...

Really? I have read that you should have a turbo timer

For example, fuel residues are often deposited on spark plugs. As you spend more time idling, the average temperature of the spark plug drops. This makes the plug get dirty more quickly

Which is why everyone needs to change to one step warmer plugs! I can't stress this enough people!

anyone want to talk about issues when excessive highway driving on cruise control?

what I have heard is that is only an issue during the early part of the break-in period.

Also for a Turbo car you need to let the car idle down for a little to bring cooler oil to the turbo. ie Turbo Timer

This is more important with diesel engines, which have MUCH higher exhaust gas temps. I had to do this with my Cummins Turbo Diesel to ensure the bearings inside the turbo stayed true. 300K miles on the original clutch and turbo... That thing was a beast. It didn't die on it's own either, someone lit it on fire.

At idle the oil pressure is at it's lowest. Internal combustion engines don't really "like" to stay at a constant low RPM, they are happiest when they get to change RPM's under light - medium loads. They weren't really designed to freewheel without any load. All these problems have been taken into consideration in modern vehicles however, so it doesn't really matter too much anymore. Idling still isn't as good for an engine as driving around though.

Guess I'm a contributor to greenhouse effect.

When the temp dips below 25 outside, I like to get into a WARM car. Period.

O.

Also for a Turbo car you need to let the car idle down for a little to bring cooler oil to the turbo. ie Turbo Timer

I used to fly Dash 8's, a turbo Prop aircraft and once we taxied to the gate we'd idle the engines for 2 - 3 minutes before shutting off the gas to let the turbines cool a little before shut down. Good idea in a turbo car as well, although probably doesn't need 2 - 3 minutes.

Which is why everyone needs to change to one step warmer plugs! I can't stress this enough people!

oh, for the love of all things internally combusted...I've come across so many threads on spark plugs and ultimately, when it comes down to it, the concensus is to get the OEM plug from the dealer (or get the same p/n plug wherever you can for cheaper) and be done with it.

on what exhaustive thread basis (or actual scientific data ) are you able to shout this from the roof tops?

oh, for the love of all things internally combusted...I've come across so many threads on spark plugs and ultimately, when it comes down to it, the concensus is to get the OEM plug from the dealer (or get the same p/n plug wherever you can for cheaper) and be done with it.

 

on what exhaustive thread basis (or actual scientific data ) are you able to shout this from the roof tops?

This is based on a long running study I have been performing on sarcasm.

- except in traffic -

Which in turn will make traffic roll even more slowly. I have recently noted people turning off their engine at red lights and it takes them a few seconds to get started and that makes the difference of several cars in the traffic flow.

Only time I idle is in the winter when there is too much fog/mist/ice on the windscreen to prevent safe driving so I have to wait until it's cleared to a level where I at least see something.

Which is why everyone needs to change to one step warmer plugs! I can't stress this enough people!

That depends on your driving conditions. A lot of slow-moving city traffic may validate warmer plugs, but for mixed driving and highway you shall use the stated plugs. For racing you may even want a step colder plugs.

Notice that the temperature on a plug is just the temperature of the center electrode/isolator and nothing else.

A plug that's too cold will get a lot of deposits and stop working because it shorts the spark to ground and a plug that's too hot will wear out prematurely, melt and/or cause self-ignition. In bad cases the isolator may crack and possibly cause engine damage.

http://www.brisksparkplugs.com.au/images/technical/heat_range_sparkplug.jpg

Idling the car to warm it up does two things:

-prolongs the time the engine runs at cold temperature which in turn has an adverse effect on wear.

-fuel dillution FTL

Stop doing it. There is no way around it. STOP doing it. Idle for 30 seconds to a minute and then drive the car without hammering on it until the engine is warm.

The end

From what I understand Subaru recommends idling the car for approx 30 seconds after you finish driving on car with a turbo. My understanding is more just to let the turbo wind down some. As someone stated, because of the way our turbos are cooled, you don't really need a turbo timer for cooling purposes but mostly just to let the turbo properly wind down.

I could be wrong though, but I know for sure Subaru states to idle the car for 30 seconds after driving to help the life of the turbo.