Faster when cold

Mister Jingles

Is there any reason in particular why some cars feel more nippy while the engine is warming up ?Mine has always done this but lately I'm curious as to why especially since after driving it for a while after it's are operating temperature it can feel sluggish taking off at times.

challengemaster

Could be sucking in hot air from beside the engine

mickdw

Mister Jingles wrote: »

Is there any reason in particular why some cars feel more nippy while the engine is warming up ?Mine has always done this but lately I'm curious as to why especially since after driving it for a while after it's are operating temperature it can feel sluggish taking off at times.

In general a car should run best at full operating temp but it could surely feel nippy at cold start stage where the fuel mix is richer and may idle abit higher.

Mister Jingles

mickdw wrote: »

In general a car should run best at full operating temp but it could surely feel nippy at cold start stage where the fuel mix is richer and may idle abit higher.

What would make the fuel richer at the start ?

Why I say runs better/nippier I mean that it feels like theres more torque and the engine is under less strain, all under 3k rpm of course.

Mister Jingles

challengemaster wrote: »

Could be sucking in hot air from beside the engine

When only started or when at operating temperature ?

Scottie99

Auatomtic choke is still kicking in giving you that extra juice

YbFocus

I'd say you're also feeling the affects of heat soak too.

The hotter the air gets before the chamber the less dense it is, in turn there's less oxygen in the same area.

Giving you less bang for your buck!

Its why your car feels so damn fast on a frosty morning

jimgoose

YbFocus wrote: »

I'd say you're also feeling the affects of heat soak too.

The hotter the air gets before the chamber the less dense it is, in turn there's less oxygen in the same area.

Giving you less bang for your buck!

Its why your car feels so damn fast on a frosty morning

Ah, frosty mornings - Nature's supercharger!

HandsomeDan

It's the auto choke. Nothing else.

Mister Jingles

YbFocus wrote: »

Its why your car feels so damn fast on a frosty morning

Never said anything about the weather, only when I start it on any morning regardless.

YbFocus

Mister Jingles wrote: »

Never said anything about the weather, only when I start it on any morning regardless.

I realise that?

It's just an example of how heat soak or lack of can have an effect.

Jesus such a reaction.
Did you just miss the rest of my post?
I'll hold off trying to help out from now on.

jimgoose

HandsomeDan wrote: »

It's the auto choke. Nothing else.

Ooh aye. But t'young folk nowadays call it cold-start enrichment.

mickdw

Mister Jingles wrote: »

What would make the fuel richer at the start ?

Why I say runs better/nippier I mean that it feels like theres more torque and the engine is under less strain, all under 3k rpm of course.

Fuel mix richer.
If it's a petrol car, depending on its age and type, it will have various systems to give it a richer mix for cold starting purposes. Very old cars would have had a manual choke where the driver would have to pull a lever for cold starting. Later came automatic choke that looked after itself. With fuel injected systems, the ecu will call for richer mix based on inputs from temperature sensors etc.

You shouldn't really be pushing the car until its up to operating temperature.

jimgoose

mickdw wrote: »

Fuel mix richer.
If it's a petrol car, depending on its age and type, it will have various systems to give it a richer mix for cold starting purposes. Very old cars would have had a manual choke where the driver would have to pull a lever for cold starting. Later came automatic choke that looked after itself. With fuel injected systems, the ecu will call for richer mix based on inputs from temperature sensors etc.

Aye. I'll just mention that earlier fuel injection setups like K-Jetronic tended to use a separate injector for enrichment. Modern EFI setups, particularly the more sophisticated sequential multipoint ones, use separate injector map-tables in the ECU.

Mister Jingles

YbFocus wrote: »

I realise that?

It's just an example of how heat soak or lack of can have an effect.

Jesus such a reaction.
Did you just miss the rest of my post?
I'll hold off trying to help out from now on.

I know you realise that, I was just clarifing it though incase others reading took it up wrong and thought I probably rally the bollox out of the car in the mornings.

Yes I did read the rest of your post, to what I can understand you've said that it's probably more to do with the engine when it's hot then cold, and that in the morning performance would be considered normal but with the heat soak it would be the reason for the drop or lack of ?

Apologies if my previous reply came as over the top.

jimgoose

Mister Jingles wrote: »

...the morning performance would be considered normal but with the heat soak it would be the reason for the drop or lack of ?...

I should say that the engine should run better and pull harder when properly at temperature. I wonder might there be a reason why it's being fed hotter air when it heats up?

Mister Jingles

jimgoose wrote: »

I should say that the engine should run better and pull harder when properly at temperature. I wonder might there be a reason why it's being fed hotter air when it heats up?

Could there be a few causes or usually just one ?
Would the TMAP sensor have any part in this ?

jimgoose

Mister Jingles wrote: »

Could there be a few causes or usually just one ?
Would the TMAP sensor have any part in this ?

It is possible, but I wouldn't even go pole-vaulting towards the conclusion that anything is actually wrong at this point. A scan of any fault-codes might be useful and quick.

Mister Jingles

The egr likes to throw up a fault code every once in a while, I've had it checked and there's nothing wrong with it. I don't really considered it that much of a problem, I'm just interested in learning as to why it does it.

jimgoose

Mister Jingles wrote: »

The egr likes to throw up a fault code every once in a while, I've had it checked and there's nothing wrong with it. I don't really considered it that much of a problem, I'm just interested in learning as to why it does it.

Could be dirty or worn. Exhaust-gas recirculation is used to lower combustion temperature a bit on turbodiesels and thus cut down on NOx emissions, so it may well have some bearing on what you're seeing. As I said, I would consider it somewhat unusual.

PBWXFORD

What type of car is it? is it high mileage etc? I have know some cars with tired engines to run better and feel more nippy when cool and seem less powerful when fully up to operating temps simply because of worn rings etc which when fully warmed up will slightly loose compression hence feeling down on power

Mister Jingles

PBWXFORD wrote: »

What type of car is it? is it high mileage etc? I have know some cars with tired engines to run better and feel more nippy when cool and seem less powerful when fully up to operating temps simply because of worn rings etc which when fully warmed up will slightly loose compression hence feeling down on power

1.8 petrol mondeo, nearing 100k miles. Was wondering that as well but it hasn't burned a drop of oil in about 4-5 months.

PBWXFORD

its unlikely to be worn engine then! It could be just the fact that when cold it feels that bit nippier with the extra fuel going into the engine until it warms up. That would make the engine feel that bit more responsive

Mister Jingles

PBWXFORD wrote: »

its unlikely to be worn engine then! It could be just the fact that when cold it feels that bit nippier with the extra fuel going into the engine until it warms up. That would make the engine feel that bit more responsive

I hope it's not, there was a few owners before me on it but I doesn't seem like a car that was abused. Yeah it looks likely now that it's either the auto choke or heat soak.

Interslice

Mister Jingles wrote: »

I hope it's not, there was a few owners before me on it but I doesn't seem like a car that was abused. Yeah it looks likely now that it's either the auto choke or heat soak.

Don't think you'll be getting any noticeable heat soak tbh.