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Old 11-09-2012, 03:27 PM   #1
Ilovecars800490
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Bmw's don't high idle on cold starts?

So, I've wondered this for a long time..

How come my 2003 bmw 330i doesn't high idle on cold starts and gradually reach idle speed as it warms up?

When i had my g35, on cold starts it would start off at 1800 rpms and slowly move down to idle until it warms up completely. bmw doesn't do that.

It seems as if the engine reaches idle speed way before it completely warms up.

Is this an emmissions thing and common with all bmw's or is there something wrong with mine?

Thanks!
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Old 11-09-2012, 03:32 PM   #2
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the manual recommends that you do not let the car "warm up" on a cold start, they suggest that you just drive it and dont rev past 3k rpm until the needle reaches normal operating temp
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Old 11-09-2012, 03:33 PM   #3
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Originally Posted by ElrichMeister View Post
the manual recommends that you do not let the car "warm up" on a cold start, they suggest that you just drive it and dont rev past 3k rpm until the needle reaches normal operating temp
This is correct as a sitting warm up causes hot spots in the oil. For the engine, it is like if you are walking through mud, then you hit a spot of water and you move quickly.
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Old 11-09-2012, 03:42 PM   #4
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There was another thread on here just yesterday or today about idle rpm on cold start....

On cold start the engine will idle slightly higher. What kind of idle rpm are you experiencing?

Mine starts around 1k rpm and as it warms up drops to somewhere around 600 - 700. So certainly not as high a cold start idle as your g35, but it does idle high initially nonetheless.

Hope that helps
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Old 11-09-2012, 03:42 PM   #5
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1800rpms? I think something was wrong with your G35. But yes, a cold idle should be ~300-400 rpms higher than a normal, hot idle.
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Old 11-09-2012, 04:14 PM   #6
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Mine does idle at about 1000 rpm when very cold.
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Old 11-09-2012, 04:15 PM   #7
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Mine does idle at about 1000 rpm when very cold.
So do both of mine. I think it's normal. Then they settle down to 600 to 700.
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Old 11-09-2012, 04:19 PM   #8
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On a civic when it's -40 (both celsius and Fahrenheit) it idles at 1500-1600.

So it does this on some cars.
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Old 11-09-2012, 04:40 PM   #9
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My idle also hovers around 1k on cold starts and works down to 600-700. I drive right away and don't go over the 3k mark until warm as well.
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Old 11-13-2012, 10:26 AM   #10
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So what you guys are telling me is that i am not allowed to warm up my car on freezing mornings like this morning? IT was roughly 23 degrees F.

What about cold winter days when i need the defroster on?

Hot spots are caused by oil not moving around enough on cold starts. A high idle initially on cold starts fixes this problem.


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1800rpms? I think something was wrong with your G35. But yes, a cold idle should be ~300-400 rpms higher than a normal, hot idle.
Every single car i have ever owned a long with all the cars my fiance and my family owned, has always high idled on really cold starts roughly around 1500-1800 depending how cold it is.

2003 G35 6mt starts off at 1800 rpms, immediately drops to 1500 than slowly reaches idle speed when the car is completely warmed up. 189,000 miles no problems and still got 6000 dollar for it.

This bmw and my friends volkswagen jetta doesn't. Starts from1000-1200 rpms and immediately drops to near idle speeds before it even reaches quarter mark on the temp guage. Which leads me to believe that this must be an emission thing and common to german cars.

As long as it's normal i guess

Seems like many things that normally would be considered abnormal are deemed normal on these german cars.
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Old 11-13-2012, 10:28 AM   #11
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Mine does, it'll hover at 1k when it's cold, then go down to normal idle speeds.
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Old 11-13-2012, 11:19 AM   #12
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1800 is high.
Mind sits around 1000 for about 30 seconds.
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Old 11-13-2012, 11:24 AM   #13
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Originally Posted by Ilovecars800490 View Post
So what you guys are telling me is that i am not allowed to warm up my car on freezing mornings like this morning? IT was roughly 23 degrees F.

What about cold winter days when i need the defroster on?

Hot spots are caused by oil not moving around enough on cold starts. A high idle initially on cold starts fixes this problem.




Every single car i have ever owned a long with all the cars my fiance and my family owned, has always high idled on really cold starts roughly around 1500-1800 depending how cold it is.

2003 G35 6mt starts off at 1800 rpms, immediately drops to 1500 than slowly reaches idle speed when the car is completely warmed up. 189,000 miles no problems and still got 6000 dollar for it.

This bmw and my friends volkswagen jetta doesn't. Starts from1000-1200 rpms and immediately drops to near idle speeds before it even reaches quarter mark on the temp guage. Which leads me to believe that this must be an emission thing and common to german cars.

As long as it's normal i guess

Seems like many things that normally would be considered abnormal are deemed normal on these german cars.
It probably just wasn't deemed necessary by the engineers. They probably figured a 50% increase in idle RPM was enough. I would think the Bavarians would know something about cars running in cold weather. Then again, they got murdered by the Russian winter in WWII because their vehicles all froze to death.

They do recommend starting it and driving while trying to keep the RPMs below 3000. Letting a car sit and idle just makes it take longer to warm up than driving it. I don't think it's going to hurt the car to idle and warm up though.

It could be an emissions thing because your car emits something like 95% less pollution out after the cats are warmed up compared to cold cats. Driving the car will also warm the cats up faster. You will probably put out more pollution in the first 5 minutes of operation than the next hour or so of driving.

Last edited by WDE46; 11-13-2012 at 11:25 AM.
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Old 11-13-2012, 12:08 PM   #14
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The bearings are not well-lubricated for the first few seconds of cold startup. Thick oil, and it's all in the pan. Excessive cold start rpm's just cause unnecessary engine wear.
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Old 11-13-2012, 02:08 PM   #15
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Hey thanks for the comments! I'm just glad it's normal.

Quote:
Originally Posted by lcoleman View Post
The bearings are not well-lubricated for the first few seconds of cold startup. Thick oil, and it's all in the pan. Excessive cold start rpm's just cause unnecessary engine wear.
Pretty much explains why bmw reccomends an 0w weght oil.

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Originally Posted by peytonracer4 View Post
1800 is high.
Mind sits around 1000 for about 30 seconds.
no, it's normal for cold starts...



Last edited by Ilovecars800490; 11-13-2012 at 02:11 PM.
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Old 11-13-2012, 03:11 PM   #16
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The high idle is caused by the Secondary Air Pump which allows the cat to heat up faster (an emission issue). European cars, imo, do not have the pump. Also, there is this thing called fast idle and slow idle. It fast idles immediately after you come to a rest. During extended stops with the engine running, it should drop to slow idle.
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Old 11-13-2012, 03:16 PM   #17
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The high idle is caused by the Secondary Air Pump which allows the cat to heat up faster (an emission issue). European cars, imo, do not have the pump. Also, there is this thing called fast idle and slow idle. It fast idles immediately after you come to a rest. During extended stops with the engine running, it should drop to slow idle.
Fast idle, then goes to a slower idle? Are you sure that is correct? Never have heard of this or seen it on my 33oci.

Last edited by richkopena; 11-13-2012 at 03:16 PM.
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Old 11-13-2012, 03:24 PM   #18
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To be honest, no. It is something I have noticed in all cars that I have owned. When you first let off the gas, the idle would position itself around 800, before dropping to 700 for example, in my BMW.
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Old 11-13-2012, 04:13 PM   #19
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Mine will idle up around 1100 if it's seriously cold.

The A6 will run up to about 1500 for a couple minutes, just long enough to scrape the windshield.

I've noticed that with the heater on, the idle is around 800 rpm. turn off the heater and it slows down to about 600. I'd assume the extra rpms are to spin the h20 pump fast enough for heat.
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Old 11-13-2012, 04:39 PM   #20
Ilovecars800490
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Fast idle, then goes to a slower idle? Are you sure that is correct? Never have heard of this or seen it on my 33oci.
They got rid of this system in most cars with Drive by wire throttle body.

old cable throttle body had a fast idle system which worked like a choke on a carburetor.

Modern cars choke automatically. Your car is suppose to run rich on cold start ups which is why high idle is needed until warm up.

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