Quick engine idle question

[RossG]

Got myself a 53 Ford Fiesta 1.4 a month ago (great step up from a 1 litre corsa). Just got a question on the engine idle. It usually idles at around 800RPM in neutral, but today I noticed when the engine was cold, at start up, it was idling at around 1200RPM. After a couple of minutes driving, it went back to 800RPM as usual. The idle wasn't really lumpy, needle moved a tiny bit but it sounded absolutley fine. Drives as well as it did before. Could this idling be due to the cold temperatures we've had over the past couple of days? I don't really know.

Any guesses?

 

[Memphis]

Yes it's the cold.

 

[RossG]

Ah good. Out of interest, why does it do that? To heat the engine up faster or something like that?

 

[Dogbreath]

All modern cars do this, the idle speed depends on the coolant temperature. A faster idle helps warm the engine more quickly and also helps prevent the engine stalling. When the engine is cold, fuel from the injectors tends to drop out of the airflow and cling onto the walls of the ports and manifold, a higher idle speed helps to minimise this.

 

[Howard]

All cars do this, the engine's no where near as efficient when cold, oil not flowing, etc

 

[The Edge]

It used to be called the choke, a cold engine needs more fuel to run properly so you used to increase the fuel in the mixture by pulling the choke out. Nowadays the engine management system does this for you, and all you notice is less mpg until warm and a slightly higher idle speed.

 

[richb_83]

It used to be called the choke

God I remember my first car having a manual choke

 

[Locky]

my bike has manual choke on it

 

[InvaderGIR]

God I remember my first car having a manual choke

My first and third cars both had manual chokes...awesome things.

 

[chipperhead]

Yep, my first two cars had choke, I used to try and get it in a bit too early then stall at the next junction.
When I got my next car without a choke I thought it was amazing.