How bad is idling...really?

[RF Overlord]

I agree with both sides; idling does no harm to a motor in good condition, but it's also wasteful of fuel and creates more pollutants.

Idling a car to warm it up in cold weather is also not very efficient, as the engine will make more heat sooner if it's doing work. People who idle their cars for 10-15 minutes in the morning are only doing it so their little tushies will be toasty warm when they get in.

 

[Clevy]

Originally Posted By: gregk24
Originally Posted By: DragRace

I've NEVER seen an properly running EFI car/truck foul plugs,it just doesnt happen.


I have no concerns about such things, what concerns me is that there is lack of oil circulation and pressure at idle, causing excess wear.




I've got vehicles with actual pressure gauges. At idle is 250kp low,I don't think so.

 

[TiredTrucker]

Well, I guess it depends on the engine. Detroit Series 60 12.7L diesels could experience spun rod bearings if the idle speed was not bumped up if the engine was idled for anything but the few minutes.

 

[fdcg27]

With any car of the last twenty five years or so, I don't think that idling hurts anything except your fuel bill.
I'll trade a little fuel for a warm and ice-free car on a below zero morning anytime.
We had more below zero mornings here over the past winter than I can remember for any winter over the past 30+ years we've lived in this area, so we idled our cars in the morning quite a bit.
I'll post a UOA of the oil from the '12 Accord in the next month or so.
The oil went in 12/22/13 and the car should be at 15% MM within the next few weeks.
We'll see what a lot of idling over the winter did to the oil.
My guess is that there'll be nothing of any note.

 

[Mr Nice]

About 2 years ago a transformer in my neighborhood went out. My wife slept in her car with the engine running from 2AM till 7AM. The air conditioning was also running for the entire 5 hours.

 

[clinebarger]

Originally Posted By: LT4 Vette
About 2 years ago a transformer in my neighborhood went out. My wife slept in her car with the engine running from 2AM till 7AM. The air conditioning was also running for the entire 5 hours.


Yep, My Suburban has been used for that a few times.

 

[EA82]

Originally Posted By: schuylkill
I shut off the car if I know I'm sitting at a long light or get stuck in a jam. Average mpg takes a huge hit when idling.

That's not an option in Florida.

 

[friendly_jacek]

Originally Posted By: RF Overlord
it's also wasteful of fuel and creates more pollutants.

 

[TiredTrucker]

yeah, the fines for idling longer than 15 min for commercial trucks in some area of the country can really lighten a wallet.

 

[Robenstein]

If you are fouling plugs in an EFI vehicle you either have something wrong in your fuel system making it run rich, you are burning oil, or someone put the wrong plugs in it and the heat range is too cool. So it can happen but there has to be something wrong either with the car or the person who worked on it.

Now on an older car, like my old Nova that had a quadrajet and a points distributor, it can happen more easily as the fuel/air metering is not nearly as precise and the ignition is a dinosaur.

As for oil pressure, most vehicles with engines that are not worn out will not have a problem.

 

[SteveSRT8]

Originally Posted By: demarpaint
For even more information search the topic, it has been discussed several times over the years. Many other members have posted their opinions on the topic as well. The bottom line is there are a lot of engines that logged some very high miles and spent a lot of time idling.


And we own some of them.

For many years the upfitter we use recommended not shutting off the engine at all unless you were going to go dark for at least 20 minutes. As a result we idled everything almost constantly between clients.

Engine life was unaffected. No properly operating late model car is harmed in any way by idling...

 

[datech]

I would guess in a modern engine idling doesn't hurt anything except excessive cold idling and an engine gets up to a normal temp much quicker under some load. But in any case it will warm up one way or another. I also don't think it hurts it to put the engine under light load shortly after it is running.

 

[TiredTrucker]

Even the new heavy commercial diesels, the OEM's are stating that they can be put under load within 5 minutes of starting. I sure wouldn't press the edge of the envelope on RPM's until the engine had fully reached operating temp.


I live on gravel roads, so my first operating of my pickup is relatively mild for the first few miles. To that end, I hardly ever idle the engine for more than a minute before taking off. By the time I reach the highway a couple of miles away, the engine is warm enough. For everything else, I rarely idle anything for more than a few minutes for any reason, be it my ag tractors, pickups, semi trucks, etc. I am one of those fortunate folks, that the OEM's provided pretty good starters, so having to restart an engine is a non issue. I feel for those semi truck operators that weren't provided starters on their engines so they feel the need to leave them idling for hours. A gallon of diesel per hour idling on a commercial heavy diesel.. man I have better things to do with my money.

 

[CBR.worm]

My first tundra would frequently idle for 8 hours a day running gear. Sometimes idling in position, sometimes idling in first gear surveying a yard.

I sold it with 220k miles and zero mechanical defects.


It's not like the old days where idling cars overheated and/ or fouled plugs.

 

[Mr_Incredible]

I think that by now we could make the changeover and assume that any car/truck we are talking about does not have a carb on it unless otherwise specified.

Idling. If the car starts cold and idles it will soon be warm. If the car is warm when the idle starts there will be no problems. A/F mix is correct, oil is circulating, and nothing harmful to the engine will occur if all systems are operating normally.

I idled whatever I was driving as I sat outside work and finished a cigar. It's my very valuable quite time. In summer, just roll down the windows. In the winter, for heat, I'd sometimes idle for 45 minutes or more. Almost every work day. UOAs show normal numbers. 40mpg car and I don't care about ecological issues or wasted fuel.

Radiator worked. Heater worked. Oil worked. No problems...

 

[Oregoonian]

Originally Posted By: schuylkill
I shut off the car if I know I'm sitting at a long light or get stuck in a jam. Average mpg takes a huge hit when idling.

SEEMS YOU WOULD HAVE LOTS OF WEAR AND TEAR ON YOUR STARTER AND OIL PUMP.

 

[gregoron]

Originally Posted By: Robenstein
If you are fouling plugs in an EFI vehicle you either have something wrong in your fuel system making it run rich, you are burning oil, or someone put the wrong plugs in it and the heat range is too cool. So it can happen but there has to be something wrong either with the car or the person who worked on it.

Now on an older car, like my old Nova that had a quadrajet and a points distributor, it can happen more easily as the fuel/air metering is not nearly as precise and the ignition is a dinosaur.

As for oil pressure, most vehicles with engines that are not worn out will not have a problem.


Or, your fuel pressure regulator valve or line is not working properly, which I just discovered after 3 years owning my car. As soon as I replaced the vacuum line leading to the pressure regulator, my idle has been more consistent and acceleration is smoother.

PS. It's easy to overlook these hoses/tubes/lines.

 

[Clevy]

So I bought my dads 89 dodge ram when he bought his 96 and his 96 ram when he bough his 02.
Both trucks ran roughly for 10 hours a day driving from site to site and idling in between.
Both trucks had in excess of 450k on the odo when put out of service. Neither even so much had a valve cover off during its lifetime.
So the 99 had throttle body fuel injection,and infrequent oil changes. The 96 was maintained only slightly better.
In my lifetime every vehicle I've ever owned idled for hundreds of hours and all went to spaceship type mileages.
My work vans drive to the sites in the winter and idle all day to keep various tools and equipment semi-warm. My vans are already at spaceship type mileages and never had a valve cover off.
So I'm going to venture an educated guess using my fleet and my vast idling experience,considering I live in Saskatchewan and in the winter I don't start driving til the window is thawed and heater is blowing heat,and I've found that idling in absolutely NO WAY SHORTENS THE LIFE OF A PROPERLY TUNED ENGINE.
In fact I'm thinking because the engines fluids are at near optimal temp the engine benefits from idling,regardless of the pennies extra in fuel costs.
If idling was an issue I'd have seen it in my fleet of used,very high mile work vans.

 

[artificialist]

Idling can be a big problem in a diesel with EGR. I knew a guy who worked on county vehicles in the early 2000s. Many of the engines he worked with were 7.3 PSD engines. Often the egr valve would hang open and hurt MPG. Other times the intake manifold would get so sooty, that the engine doesn't breathe efficiently either.

 

[ueberooo]

Originally Posted By: friendly_jacek
2 things: fouled plugs and fuel in oil. Not catastrophic, but not good either.


I would actually think that you usually help reduce fuel in oil, because the high manifold vaccum (in gasoline fuel injected engines) would cause the PCV valve to suck up gasoline vapors boiling off the oil pan.

This is assuming the oil is hot, and the pcv valve works.

Cold start idles are a whole different story. The computer is programmed to burn rich, and loads of fuel that cannot possibly be burnt is injected into the cylinders. It's also when the cat isn't warmed up and functional. You can smell the result.

On traffic lights on a cold engine with pedestrians and people around, I'll often turn off the engine. Saves fuel too, at the sight expense of the starter and timing belt wear. Idling uses about a gallon every three hrs, for a typical 4 cyl.

Short trips plus cold climates is what causes fuel dilution in oil; idling a warmed up engine with hot oil does the opposite. Cold idle, warm idle are two different things.