Should my car feel slower with a cold engine
Discussion
Willy Nilly said:
It wouldn't be hard to put something in the ECU software to limit power until up to operating temperature. It might be that under normal driving conditions you never notice it, but if you try a WOT rally start you'll only get a percentage of the max power, or even not going to high idle.
This basically, limits to boost, engine running a little richer, probably torque limits in higher power stuff, exhaust flaps closing to warm up catalytic converters quicker, higher idle revs until warm. Every modern car I have driven is slightly sluggish at first, you would not notice this if you drive normally as said above. Most engine wear happens from cold start so it would be daft for manufacturers not to factor this into their engine mapping.
The other thing of course is that cold oil won't circulate as quickly as it is thicker, so there is additional drag.
Edited by Mike335i on Sunday 5th February 12:14
MJK 24 said:
willmagrath said:
True but it warms up pretty quick! Its never 5 mins though 
When the temp gauge is showing the coolant is warm, the oil will still be lagging way behind. I would wait a good 15 mins with that engine before giving it some beans. Unless you only intend to keep it a few years. For example, on my old 106 the oil temp gauge wouldn't budge with the oil below 20', and by the time the water temp read normal with the stat open (approx. 5 mins of normal driving) the oil temp was approximately 45'.
For modern oils it's a fairly fast process, see below for 5w40:
legless said:
The coolant temperature usually rises to normal within 5 minutes. It takes 20 miles of motorway speed though for the oil to get up to temperature.
20 miles?! 
Does that mean I should drive 40 miles if I was in 30 zones before I could put my foot down?
That seems very excessive TBH.
MJK 24 said:
I would wait a good 15 mins with that engine before giving it some beans. Unless you only intend to keep it a few years.
I'd be very surprised if thats true providing you are using quality in spec oil. Manufacturers know that the vast majority of journeys are only a couple of miles and oils/engines are specced for that.TameRacingDriver said:
legless said:
The coolant temperature usually rises to normal within 5 minutes. It takes 20 miles of motorway speed though for the oil to get up to temperature.
20 miles?! Does that mean I should drive 40 miles if I was in 30 zones before I could put my foot down?
That seems very excessive TBH.
TooMany2cvs said:
Krikkit said:
especially on a standard engine with an oil/water heat exchanger
Relatively few vehicles have oil-water heat exchangers, unless you're counting the engine block itself as that.
Actually I believe it is pretty common, from a quick google even things like the Mondeo 2.0TDCI, Transit, even the Focus 1.6i have one.
Even at the motorway speed limit, my diesel Passat is still turning at less than 2000 rpm, and for non motorway driving it can take up to 20 to 30 minutes for the cooling system to reach normal operating temperature, (with the oil temp lagging well behind even those times) at these low rpm`s.
Surprisingly after just half a mile or so, the heating system `can' put out warm air, but with the exception of the screen clearing setting, I tend not to use the heating system until the engine has reached as near to normal operating temp as possible, to allow it to warm up as quickly as possible depending on external temperatures.
Surprisingly after just half a mile or so, the heating system `can' put out warm air, but with the exception of the screen clearing setting, I tend not to use the heating system until the engine has reached as near to normal operating temp as possible, to allow it to warm up as quickly as possible depending on external temperatures.
Pan Pan Pan said:
Even at the motorway speed limit, my diesel Passat is still turning at less than 2000 rpm, and for non motorway driving it can take up to 20 to 30 minutes for the cooling system to reach normal operating temperature, (with the oil temp lagging well behind even those times) at these low rpm`s.
That's diesels for you. They don't put as much heat into the cooling system as petrol cars which means they take far longer to warm up. Pan Pan Pan said:
Surprisingly after just half a mile or so, the heating system `can' put out warm air, but with the exception of the screen clearing setting, I tend not to use the heating system until the engine has reached as near to normal operating temp as possible, to allow it to warm up as quickly as possible depending on external temperatures.
Probably got a pre-heater in it. Very common now both as fuel economy is (relatively) poor when they're cold and because it's plain unpleasant to be in a freezing cold car for 30mins before you get any heat from the heating.It was also one of the things I hated about driving a diesel in winter. With a ~30min commute it would *just* start feel the first hint of warmth from the heating in the last mile or so before I got home. I was always cold and very glad to hand it back.
Fastdruid said:
Pan Pan Pan said:
Even at the motorway speed limit, my diesel Passat is still turning at less than 2000 rpm, and for non motorway driving it can take up to 20 to 30 minutes for the cooling system to reach normal operating temperature, (with the oil temp lagging well behind even those times) at these low rpm`s.
That's diesels for you. They don't put as much heat into the cooling system as petrol cars which means they take far longer to warm up. Pan Pan Pan said:
Surprisingly after just half a mile or so, the heating system `can' put out warm air, but with the exception of the screen clearing setting, I tend not to use the heating system until the engine has reached as near to normal operating temp as possible, to allow it to warm up as quickly as possible depending on external temperatures.
Probably got a pre-heater in it. Very common now both as fuel economy is (relatively) poor when they're cold and because it's plain unpleasant to be in a freezing cold car for 30mins before you get any heat from the heating.It was also one of the things I hated about driving a diesel in winter. With a ~30min commute it would *just* start feel the first hint of warmth from the heating in the last mile or so before I got home. I was always cold and very glad to hand it back.
On the plus side of course comes the 1000 miles per tankful range, and not having to stand on a freezing cold, windblown, garage forecourt, having to fill it up every few hundred miles
Guvernator said:
Conversely once it is up to proper temp, a turbo car loves cold air. All my turbo cars have had noticeably more fizz when the weather is cold, I used to love taking them out for Winter morning blasts.
Agreed. I always notice an improvement in my turbo (diesel in my experience) performance on a cool, crisp day.Pan Pan Pan said:
As touched on in another thread that is one of the reasons why I tend to wear clothing suited to the external conditions extant, when using the diesel.
On the plus side of course comes the 1000 miles per tankful range, and not having to stand on a freezing cold, windblown, garage forecourt, having to fill it up every few hundred miles
Meh, cold once every 1-2 months filling the car up is preferable to every time I drive it. On the plus side of course comes the 1000 miles per tankful range, and not having to stand on a freezing cold, windblown, garage forecourt, having to fill it up every few hundred miles
YMMV
The turbo itself operates far better and more efficiently once it has seen some proper heat.
The first time you run up a turbocharged car on the rolling road it isn't as responsive or powerful till the turbo has heated up. This is especially evident in the lower rev range. IE the turbo boost threshold his higher up the rpm on a cold engine.
I am not saying this is the answer instead of the suggested reduced boost when cold by ecu, but it will be a factor either way.
RW
The first time you run up a turbocharged car on the rolling road it isn't as responsive or powerful till the turbo has heated up. This is especially evident in the lower rev range. IE the turbo boost threshold his higher up the rpm on a cold engine.
I am not saying this is the answer instead of the suggested reduced boost when cold by ecu, but it will be a factor either way.
RW
GloriaGTI said:
Surely at motorway speed it will take that long, as the engine is going to be turning over at lower revs, no?
No - its the heat of the combustion that provides the majority of the heat, so the engine speed isn't that relevant. if there is lots of fuel going in then there will be heat. A large 4x4, for example, pushing a huge hole in the air will heat up nice a quickly at 75 even with interstellar gearing. Fastdruid said:
Pan Pan Pan said:
As touched on in another thread that is one of the reasons why I tend to wear clothing suited to the external conditions extant, when using the diesel.
On the plus side of course comes the 1000 miles per tankful range, and not having to stand on a freezing cold, windblown, garage forecourt, having to fill it up every few hundred miles
Meh, cold once every 1-2 months filling the car up is preferable to every time I drive it. On the plus side of course comes the 1000 miles per tankful range, and not having to stand on a freezing cold, windblown, garage forecourt, having to fill it up every few hundred miles
YMMV
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