Hello everyone, ever since the cold weather has set in here in the UK (last 2 weeks) my 1999 Focus 1.4 has started playing games when cold starting.

Here is an extract from an e-mail I sent to a guy I know at ford, looks like hes too busy to reply at the moment:

"...Ever since the cold weather has set in so sort of the last 2 weeks if that, when I cold start the car like I am just about to now, it will rev a little erratically. It does it when its idling. You get the usual high revs for the choke and then it will go down to 1,000 RMP and then quickly jerk from 1000 to 1100 every second. It lasts about 5 minutes last time I just had to drive the car as I was late and it continued to do it at every junction I got to even when I arrived at Bishops Stortford it was still doing it. (Thats a town about 20 minutes drive away)

Once its warmed up, it seems to be fine. Do you have any ideas as to what could cause it. I usually cold start it and leave it for 1-2 minutes before driving as this is supposed to be good for the engine as opposed to just starting and driving."

Thats my e-mail. And yes, basically I'm confused as to what it could be. It takes the orange engine coolant which is just above max and has been since Feb 07 when I got the car from ford second hand. The car is very jerky if you pull away when its doing this funny business with the revs, its almost like your clutch is on the way out and then it suddenly kicks in and pulls along. - Clutch is fine.

Any help would be super.

 

Idle Air Control valve (remove and clean with carb cleaner including the Throttle body)

or Inlet air temp Sensor.

.

 

also worth changing the coolant temp sensor as that give a reading of water to the ecu how cold or hot it is ect and can cause the problem your are haveing up untill its warm

 

Hi, thanks for your reply. I have quite a bit of common sense about cars or engines, but I have no idea where the Idle air control valve is. Is it the part that connects to the air intake pipe that goes into the engine. I know there is a sensor there which monitors how much air is going in to the engine.

The only other thing I thought it could possibly be would be the fact its only a little 1.4 focus engine and maybe its finding it hard to give enough power to get everything going when its cold. Its a bit of a long shot but I have taken the fuse out of my amplifier just to see if it makes any sort of difference. The power on the car (either engine or altornator) are none too good and frequently do things like dim headlights when you put the breaks on whilst coasting doing anything over 20. Strange power realted things like that.

Anyway thanks for the post, and if you could give me any info as to where the sensor is, I will see if I can clean it up.
Cheers rob