Engine RPM at IDLE?

[lonelyreza]

Hi guys!

Please tell me your cars engine rpm at idle.
In other words when you start your car (consider the engine has become warm after a while and works normally) without depressing the gas pedal, what is your engine rotation speed? (rpm=round/min)
I have seen one that stands at 1000 rpm (picture below) which I think is not OK, because usually six engines at idle are 800 rpm.
Please share your experience.

[riccis]

I'm using another car at the moment but from memory would agree with you that it's around the 700 to 800 rpm mark.

Will check when I'm next in the car and report back.

[tiborakos]

From memory i believe Z35i is at 800.
Which model u have?

[Otago]

700 - 800 rpm, air-con off.

[lonelyreza]

That car is sdrive23i

[Memphis1]

regardless of the engine, most are 700-900, have you messed with the engine at all??

mine is 800

[msimon18]

If the engimne is running at idle why are all the idiot lights on ?????

[siscobmw]

700rpm, hot engine, cold starts from 1200(very cold) and then goes down to 900 rpm for a while.....after some miles 700...

[zentra]

from the picture, it seems to be cold start and rpm couls even go beyond 1k and gradually decrease.

[tiborakos]

yep, since all lights are on, it is just a sec after start, so i guess it will settle to lower RPMs later...

[Z4 Beemer]

Originally Posted by tiborakos

yep, since all lights are on, it is just a sec after start, so i guess it will settle to lower RPMs later...

Yes, I would agree with this.

[mrboon]

600rpm here

[zeez_Dubai]

am 600 rpm too.

[zEdP]

30i 550 rpm.

[tranquility]

Bump for this: mine is around 1,100rpms...something wrong?

[toplessrydr]

If you notice our Z takes much longer to warm up. Normal operating temperature is just below the half way mark on the gauge. You would need to run it for a good 15 min before you can say it is at normal operating temperature. And I mean highway 15 min. So before it fully warms up it will idle high at around 1000rpm. Seems normal to me.

[raven333]

Originally Posted by toplessrydr

If you notice our Z takes much longer to warm up. Normal operating temperature is just below the half way mark on the gauge. You would need to run it for a good 15 min before you can say it is at normal operating temperature. And I mean highway 15 min. So before it fully warms up it will idle high at around 1000rpm. Seems normal to me.

What you are looking at is the oil temp gauge, Z4 E89 do not have a water temperature gauge!!!!! hence the oil takes longer to heat up but nor as long as my last 6 series, that V8 took ages for the oil temp to rise....

As for RPM's it depends on what you have running when the car starts and begins its warm up, I don't believe you have an issue........

[tranquility]

How come the range is so wide: from 600 to 1,100? This is weird.

[raven333]

Firstly the idle is set electronically and will depend on what is running on the car at startup, for example lights, aircon, engine temp. if you switch these things on and off when the car is idling you will see. There are other factors, even petrol grade can make a difference.
Yes there are some items that when they fail can affect the idling but they also manifest themselves as other problems.
You can take your car back to the dealer and ask them to read any error codes to see if anything is amiss, or take it to an independent who has a code reader... hope this helps....

[eugenelee]

There really doesn't seem to be anything to worry about. Because of the huge amounts of electonics that are trying to optimise the performance of the car through balancing the air intake and fuel flow and so on, ambient temp, air flow to the car, etc, they all play a part.

Plus from your photo, your engine is cold. So that will cause your rpm to run high as well. Something to do with the amount of air that the engine needs but is not geting or the density or something like that and so the rpm is revved up to compensate. I'm no expert here but that's the general ballpark. Even carburettor cars do that so it's perfectly normal.

So don't worry about it UNLESS your rpm is still high when your temp is at 90-120. Then take it in for a tune.

[rking117]

There are a couple things that are important to consider when determining Idle.

1. The ambient temp and barometer condition
2. The temp of the engine

You might ask why, first the engine temp is obvious. The cold metal in the vehicle will cause the fuel to combust more violently. The car should compensate for this by adding more air to the combustion chamber to allow for the higher combustion rate thus giving a higher RPM rate. An interesting note: We used to pack our fuel rails with Dry Ice on race cars to dramatically lower the temp of the fuel before an during the race to get an extra few horses.

The second is Barometer reading. I think it is the lower the barometer the less volitile the fuel will be. There are other factors as well such as humity are also issues that can affect volitility.

either way while the "Choke" (albeit electronic) will cause the engine to run at about 1000 RPMs or in some cases a little higher then after a short period depending on temp it will settle to around 650 RPM.

Hope this very short explaination helps you to understand the science behind the engine RPM variation.

[bmwmick]

WOW!