How bad is letting your car idle for long

[Loves2Rev]

I went out to warm up my car yesterday morning and walked back in, turned on the TV and something interesting was on and I totally forgot about the car for at least 20 minutes. :sad

I know this is bad but why, and what is it gonna do?

Thanx in advance.

[WillyK]

I don't know why it would be bad, just burning gas.

[redcel180]

Not good for the spark plugs. If you do that then get out on the interstate and do 85 mph for a good 20 min. and burn the carbon off of the spark plugs. Carbon builds up when you are not driving your car and just letting it idle.


Brett

[Loves2Rev]

Ahhh, there you go.

Thanx a lot redcel, I knew something bad comes of it. Guess its time to drive like a maniac on my way home then. :D

[The Game]

I leave the car idling for about 3-4 minutes just to warm up. is that bad???:( :confused:

[Kit99bar]

your wasting your time warming it up

just turn it on, wait 30 sec then drive
leave it under 3K

it's the best way to get the oil circulating and warm it up

idling it will just waste gas

[VZV21]

Not enough oil pressure generated when the engine is doing 700 rpm to properly lube the heads

[The Game]

Originally posted by Kit99bar
your wasting your time warming it up

just turn it on, wait 30 sec then drive
leave it under 3K

it's the best way to get the oil circulating and warm it up

idling it will just waste gas

Thanks:D

[oldster]

Originally posted by VZV21
Not enough oil pressure generated when the engine is doing 700 rpm to properly lube the heads

I would be interested in where you got that theory. When you start up you are on fast idle so it wouldn't apply but what happens when you are idling normally at traffic lights etc? Did Toyota design an engine that will self destruct at idle?

[oldster]

Originally posted by redcel180
Not good for the spark plugs. If you do that then get out on the interstate and do 85 mph for a good 20 min. and burn the carbon off of the spark plugs. Carbon builds up when you are not driving your car and just letting it idle.


Brett

With Toyota's engine management system I would be very suprised if 20 minutes of idling would do anything that would need to be worried about at all.

[Blk00SS]

Carbon on Spark plugs? F that... I don't care. I let it warm for 15-20 mins now because i like a toasty car :)

[AznThugg2002]

i have an older celica but i let it idle at da start. itz got a high idle start and im thinking that would be so u can let it sit to warm up and also get oil pressure and everything up.

[VZV21]

Originally posted by oldster


I would be interested in where you got that theory. When you start up you are on fast idle so it wouldn't apply but what happens when you are idling normally at traffic lights etc? Did Toyota design an engine that will self destruct at idle?

Everyone does, otherwise the standard idle would be a gas guzzling 1500 rpm. That's why it's not recommended to let the car idle for a long time.

[oldster]

Originally posted by VZV21


Everyone does, otherwise the standard idle would be a gas guzzling 1500 rpm. That's why it's not recommended to let the car idle for a long time.

OK, let's try it another way. Explain to me why you would not be getting oil to the head at 700 RPM. Please don't tell me pressure unless you can state catagorically the differences between 700 and 1500 RPM. :confused:

[VZV21]

the oil pump is churning out oil (we need to know the characteristics of the oil pump). Obviously oil needs to fight gravity and friction to get to the heads (and all those oil passages). Because of the oil flow is turbulent (if it was laminar, it would be a hell lot easier), it complicates the math (if someone wants to work it out, I can't since all my fluid dynamics books are at work, as huge paperweights). WIth the two corresponding input rotational velocitys, who have two different values (of velocity & pressure) for each one (idle & fast idle).

Just imagine for a moment, all the oil passages to get to the head (ideally we like to assume stuff like constant flow, constant pipe diameters, smooth walls, no alternate routes, oil flows directly to the head, etc. to make life easier). There's two methods of examining this problem, Pressure or Velocity.

If we want to determine the final velocity, we can assume that gage pressure (psig) when it reachs the head to be a known value (we like to use 1 atm or 0 psig to make life easy)

If want to determine the final pressure when the oil reaches the head, we need to make an assumption on final velocity (again, we like 0, for some predetermined value)

Thanks to Bernoulli's work in Fluid Dynamics, Pressure is a big deal, and because of him, his formulas lay the groundwork of the complicated algorithms engineers have to go through to determine fluid dynamic stuff. Even using CFD software, same old sh!t to deal with.

Though I wish I could come up (out of my ass) two values to feed you, it's little hard to do, especially without knowledge of every nook & cranny of the engines. THis is why Mechanical Engineers gets paid the big bucks do engineer this stuff (though we make less money compared to other engineering fields on average).

Without the proper specs, I cannot determine (roughly) what the corresponding pressures or velocities may be.

Engineering calculations (& modeling) can be a real bitch to do sometimes (wait a lot of times)

Hope I filled up with enough crap I go through daily at work (just the math part)

[MikeM380]

I went out to warm up my car yesterday morning and walked back in, turned on the TV and something interesting was on and I totally forgot about the car for at least 20 minutes.

I know this is bad but why, and what is it gonna do?

<B> Its not bad. Your car is fine. You wasted a quarter of a gallon of fuel if that. Oh and exhaust and combustion bi-products will build up at idle or during drive. No worries.

Mike
</B>

[oldster]

Originally posted by VZV21
the oil pump is churning out oil (we need to know the characteristics of the oil pump). Obviously oil needs to fight gravity and friction to get to the heads (and all those oil passages). Because of the oil flow is turbulent (if it was laminar, it would be a hell lot easier), it complicates the math (if someone wants to work it out, I can't since all my fluid dynamics books are at work, as huge paperweights). WIth the two corresponding input rotational velocitys, who have two different values (of velocity & pressure) for each one (idle & fast idle).

Just imagine for a moment, all the oil passages to get to the head (ideally we like to assume stuff like constant flow, constant pipe diameters, smooth walls, no alternate routes, oil flows directly to the head, etc. to make life easier). There's two methods of examining this problem, Pressure or Velocity.

If we want to determine the final velocity, we can assume that gage pressure (psig) when it reachs the head to be a known value (we like to use 1 atm or 0 psig to make life easy)

If want to determine the final pressure when the oil reaches the head, we need to make an assumption on final velocity (again, we like 0, for some predetermined value)

Thanks to Bernoulli's work in Fluid Dynamics, Pressure is a big deal, and because of him, his formulas lay the groundwork of the complicated algorithms engineers have to go through to determine fluid dynamic stuff. Even using CFD software, same old sh!t to deal with.

Though I wish I could come up (out of my ass) two values to feed you, it's little hard to do, especially without knowledge of every nook & cranny of the engines. THis is why Mechanical Engineers gets paid the big bucks do engineer this stuff (though we make less money compared to other engineering fields on average).

Without the proper specs, I cannot determine (roughly) what the corresponding pressures or velocities may be.

Engineering calculations (& modeling) can be a real bitch to do sometimes (wait a lot of times)

Hope I filled up with enough crap I go through daily at work (just the math part)

Or to make a long story short, you have no valid data to support your assertion that the heads are damaged at 700 RPM due to low oil pressure.:D

[daSchtick]

You idled your car for 20 minutes, so what. The engine has been designed to tolerate idling. You do not need to drive 85 MPH to "burn off the carbon", and the oil pressure is more than sufficient to continually lubricate the engine at 700 RPM.

In the days of the carburetor, the imprecise mixture could cause excessive fuel in some cylinders, and cause spark plug fouling or gas saturation in the oil, but with today's engine (and emission) controls, these are a thing of the distant past.

If engines could not tolerate idling, then what about all of the taxis and police cars that idle regularly for extended periods.

The only way you will damage your engine is through mis-shifting, but from what I read on this site, it prevents death.

[oldster]

Originally posted by daSchtick


The only way you will damage your engine is through mis-shifting, but from what I read on this site, it prevents death.

That's a classic. :D :D :D :D :D

[Loves2Rev]

Hey guys didn't mean to cause such a stir, its just that I'm pretty sure I have read either on the board or in the owners manual that idling for long periods of time was bad.

Either way this conversation has become very interesting and I am glad to hear that my engine should be A okay. :)

[WillyK]

I don't worry about it too much. Like Ron, I like having my car nice and toasty when I leave for work so I let it idle for about 5 to 10 minutes usually. Cold leather stinks in the mornings :mad:

[xdannyx25]

i know people tha have cars tha they dont use all the time, and they just start it up let it sit and run for like 20 mins once in a while, but i know about the intercoooler and crap, and to cool the car, but i really dont think it'll hurt anything, maybe if you did it everyday.:)

[afghan]

You know carbon builds up like snow on our Michigan cars because we like them to warm up.

The only way to rid of carbon deposits after warming for long time is to go 85 to 90 for 5min! Don't go over that.:rolleyes:

[t2000gts]

i let my car warm up for 3-4 minutes in the mornings...i like it nice and toasty too :D

but i'm soon driving at around 75-80 on the highway. so i guess that's good.

i actually let it warm up until it idles down to 1100-1200. it starts off at 1500 cold. if it's outside, it starts at 1700. the time it takes to idle down varies.

[spaldam]

Originally posted by afghan
You know carbon builds up like snow on our Michigan cars because we like them to warm up.

The only way to rid of carbon deposits after warming for long time is to go 85 to 90 for 5min! Don't go over that.:rolleyes:

Why do you have to go 90 mph? You could just go 40 in 1st at 8000 rpm for 5 min. The engine dosen't care about mph as much as it does about rpm.

Also, your just wasting gas, and ideling is more prone to allow carbon buildup, and that's why the Owners Manual says to not let it idel for long periods of time.

[CeliRacer]

wow! talk about old posts! :)

[Kry]

i always drive.. i dont warm up..... i just keep the car under 3k

[spaldam]

My freinds always look at me funny and wonder what I'm talking about, becauwe I have a tendancy to go back to an old subject that they had all forgotten about.

[NSX_GTR_LM]

goddamn sh!t, brought back from the dead, lol

[Quakey]

hi ppl,

i have an auto gt and if i dun warm up for like a few minutes in the morning and shift to R then my car would just shake! i hope it's not a big problem..?

[oldster]

Originally posted by spaldam
My freinds always look at me funny and wonder what I'm talking about, becauwe I have a tendancy to go back to an old subject that they had all forgotten about.

Yeah well we don't think it's all that funny so knock it off. :) Hope you also know that is an old people habit........:wtf:

[2002GT_Celica]

Originally posted by Quakey
hi ppl,

i have an auto gt and if i dun warm up for like a few minutes in the morning and shift to R then my car would just shake! i hope it's not a big problem..?

Is it because the rpm's are high? Somewhere around 1500? Because my car does that and it's fine.

[spaldam]

Originally posted by oldster


Yeah well we don't think it's all that funny so knock it off. :) Hope you also know that is an old people habit........:wtf:

Yeah, well I did just turn 26, and all the sudden I've have a few people trying to set me up on dates. Like I'm some kind of menous to society because I'm not married.

[soceur]

i thought i had read this before!!

[SilverRide]

Hey people, isn`t "prolonged" idleing bad for a CAT because it can overheat and it tends to cloge up?

[t2000gts]

the car idles at 1500 when cold. i just let it warm up to one tick when it's been sitting overnight or something, usually takes 2-3 minutes. the rpms go from 1500 down to 1200 in that time. then i leave.

[Zorn]

Originally posted by Blk00SS
Carbon on Spark plugs? F that... I don't care. I let it warm for 15-20 mins now because i like a toasty car :)

WOW - blast from the past!