Higher rpm tickover when cold

[Laurie61]

Hi, noticed this yesterday for the first time. When the car is started tick over is steady at 975 rpm, it stays at this level until water temp reaches normal and then drops back to normal over a 2-3 sec period ?

Anybody encountered this before, outside temp was 4C but wouldn't think this would have any affect. Any thoughts ?

[LS108]

look at what happens when it is a bit colder

 

http://www.youtube.com/watch?v=pHtza6iJVsw

Edited 26 November, 2013 by LS108

[Nathanio]

look at what happens when it is a bit colder

http://www.youtube.com/watch?v=pHtza6iJVsw

-25c! Jeeeez that's cold! Looks like it struggled a bit there!

[LS108]

-25c! Jeeeez that's cold! Looks like it struggled a bit there!

 

If to look at this particular video - spark plug heater was working way too short. Either he had heated them before starting filming, or there is some kind of problem with it - and that might be the reason why engine have started not so nicely. Also the question if he used proper winter diesel.

[ksr]

Hi, noticed this yesterday for the first time. When the car is started tick over is steady at 975 rpm, it stays at this level until water temp reaches normal and then drops back to normal over a 2-3 sec period ? Anybody encountered this before, outside temp was 4C but wouldn't think this would have any affect. Any thoughts ?

 

Perfectly normal behaviour, in my book, for any car, whether petrol or diesel. Only thing that seems slightly odd is that the idle speed didn't drop until you had got up to normal coolant temp (88-90 deg. C). I would expect idle speed to drop in stages as the engine begins to warm, rather than all at once when it had reached normal operating temperature.

[Laurie61]

Perfectly normal behaviour, in my book, for any car, whether petrol or diesel. Only thing that seems slightly odd is that the idle speed didn't drop until you had got up to normal coolant temp (88-90 deg. C). I would expect idle speed to drop in stages as the engine begins to warm, rather than all at once when it had reached normal operating temperature.

Not noticed it before, I thought the tick-over was maintained at 750-ish rpm irrespective of engine temp ?

[wokwon]

Not noticed it before, I thought the tick-over was maintained at 750-ish rpm irrespective of engine temp ?

 

There's lots of things that can increase the idle speed such as:

 - Engine load sensor (e.g. extra loads like the aircon compressor is working hard);

 - Alternator load, if the load demand is higher than what the alternator can supply at idle, it increases the idle speed;

 - DPF regeneration;

 - Emissions control (less of this with a diesel but it still can happen, warming up cats etc). This is usually the one that happens with low engine temp;

[jonnie5]

Yip as above. Now done 50k in my Superb. My last vrs taxi did this and the 3 caddys I drove before that all did this.

Sent from my Windows Phone 8X by HTC using Board Express

[Laurie61]

Yip as above. Now done 50k in my Superb. My last vrs taxi did this and the 3 caddys I drove before that all did this.

Sent from my Windows Phone 8X by HTC using Board Express

 

So I can avoid a visit to the garage, thanks

[silver1011]

I just noticed this too. It's only started doing it with the recent low temperatures.

 

I'm super concious of RPM's as I had a troublesome DPF on my previous Octavia so am well aware of varying RPM's.

 

My CR140 when started on a morning from cold sits at 1,000rpm which it never used to through the summer.

 

I don't know how long it stays high for as after I leave the drive I don't stop unil the engine is well up to temperature.