Aruca Xst

on startup it starts somewhere around 800..and sometimes it hovers around 12 or 1300 then decreases then it slowly goes down..i am a noob..i just noticed this today so i was wonderin wat rpm do u guys hover around on an idle engine..

ferio8

haha thats fine at all.. every injected engine warms up first then goes down to about 800 rpm when it heats up. thats why its not good to drive right away after the engine starts. let it warm up first for about 3 minutes.

DJMcGee

You are correct that all vehicles increase idle speed when cold, mixture is adjusted as well. Anyway, where you are wrong is waiting 3 minutes for it to warm up before you drive. Heat is generated more quickly when a vehicle is driven than when idled. A car should be started and then waiting no more than 30 seconds driven. Unless you live in a location with extremely low temperatures there is nothing else for you to do. Longer idle times waste fuel and generally increase engine wear.

It's amazing how many of these "old wives tales" still persist today.

its rayden

yup. i used to let the car warm up in the winter for a few minutes but last winter i started to drive off after a minute. i always take it easy on the gas pedal until the car has hit it's operating temps for at least 5 minutes.

ttk5

letting the engine warm up is a myth....

ressling

Then explain why engines dont always start when in below freezing temps for prolonged periods of time?

Seeing as you are in Vancouver, I'd like to see a better explanation than "It's a myth".

While it hasn't happened often to me, there were periods growing up in the Midwest (notably coming back to my car parked for a week at the airport in the winter) where the car wouldn't start due to cold.

huludicidal

Growing up and living most of my life in MN, warming your car up was no myth. Although the length of time might be.

From an engineering standpoint, you can understand that when you cold start a car, there will be a severe negative temperature gradient radially from the cylinders outward. Thus, the combustion chamber is very hot but the metals around it including your piston rings, will not have reached their steady-state operating temperature. It is not uncommon to hear of older vehicles cracking rings or blowing head-gaskets by just starting up and driving off.

Similarly, although oil viscosity is described as 5 cold 30 warm (5w-30), in very cold conditions, oil is very thick (not 5). This is most noticeable in the gearbox where it can be extremely difficult to move the gear selector before warmed up.

Dynamic temperature gradients associated with cold startup can push the engine to operate under conditions for which it was not designed for. Putting it under load can magnify this. Thus, I always support a 30sec warmup during warmer months and longer for cold months. This gives me the peace-of-mind that oil is fully circulated and extreme temperature gradients are equilibrated.

ttk5

Maybe Im just being ignorant or too trusting of the internets, but a quick google search will tell you that most modern cars do not have to be "warmed up" before being driven. I was curious about this in the past because I live in vancouver but all I hear and see about this issue is that it simply just is not true anymore with todays modern cars. I agree that it may not be a good idea to rip your car immediately after starting it up on a cold day, but for regular day to day driving I've adpoted the belief that a 3min warm up is just not necessary as much it is a waste of gas.

09TSXTech

That's my rule of thumb also.

pinatubo

I think you guys went to hard on ttk5.
I think what he meant for the "warm up" (meaning idling engine for a period of time) is unnecessary for new vehicles, nowadays.
When I still owned the Prelude '89, I used to "warm it up" for good 5 or 10' before start driving (actually, I warm ME up)
With the Accord 03, I took about 1 or 2 minutes before driving.
That 1 or 2 minutes are NOT required, I could have just driven away right away, no need to wait.

09TSXTech

No need to be apologetic. Most new cars do not require long warm up period if any, actually Vancouver has an anti-idling bylaw. That's why I just wait 30 secs, (usually the amount of time my kids put on their seat belt) before driving off.

For you older members, I used to drive a 1974 Datsun 710 and a 1978 Civic with manual choke and carburetor, warm up is a requirement

DJMcGee

There is no hostility here.

You will note in my previous post that I specifically excluded discussion about starting in extremely cold temperatures. Having lived in parts of the country where the winter ambient temperature gets to -20 °F, I certainly understand that cold weather starting and driving are different than even cool - hot weather starting.

In answer to a post above, the reason cars won't start in extreme cold is from a multitude of reasons:
1. Batteries perform much poorer in a cold environment. Their capacity falls with temp.
2. Oil at extremely cold temperatures is more viscous and difficult to pump.

Thus on extremely cold mornings, which here in Pittsburgh I classify as below 10 °F, I start the car, let it warm for 30 sec to 1 minute then drive easily my first 4 miles until I reach the highway. I never, never "hot rod" any vehicle until it's operating temperature is normal.

You should follow a similar philosophy.

However, when it is warmer I just start and go. My TSX is in the normal temperature range in less than a mile. Same philosophy on hot-rodding.

Your exact implementation many vary but a warm-up of anything over 1 minute is wasteful in any but the most extreme conditions - which 99% of us don't live in and of those 1% that do it is not frequent.

Good luck.

ttk5

thank you

fahzz

I'd Like to resurrect this thread if I may. I have a brand new base TSX sedan with an automatic transmission. I live in New England, but it hasn't been very cold since I got the car. Whenever (as in anytime) I start it it idles around 1200 RPM for a very long time i.e. 15 to 20 minutes before finally dropping down to around 750 to 800. On my five minute drive to work, the car will travel at up to 25 mph with my foot off the gas, until I brake, and the car shifts to a lower gear.
It's been a while since I've driven a car with an automatic, and I need to know if this is normal behavior or if this should be adjusted. This can't be good for the brakes.
Thanks.

benben01

^^ That does seem like a long time to get the engine down to the idling rpm range. Even in frigid temps (~0 degrees) I have had mine idle around 800 rpms in less than 10 mins and the car is nice and toasty when I get in. May want to have the idle control valve or what ever it's called and see it is functioning normally.

Professor

Most of the time if I want to reduce the RPM idle, I hit the gas once and it drops to 800 RPM or so.

PyroDave

i've tried that several times, usually it goes back to whatever RPM it was cold idling at. shifting to neutral drops the RPM, but idk if that should be done. i always assumed car was just trying to warm up quicker, so i let it be although i never used to notice it until like 2 months ago

fahzz

I'm reporting back. Went to the dealer today and was told that this is normal behavior. Computer analysis turned up no faults, and apparently TSX's idle high by design. It must be a "feature", like auto lock, which I'm sure will eventually "automatically" lock my keys in the trunk inside my golf bag. These are the two things that I find annoying with the car.