Started the car as normal this morning and drove off. About 200 metres down the road, I did my usual left turn. However, as I started to accellerate, I noticed it wasn't as smooth as usual. I'm always very gentle with the throttle when the engine's cold, so it was nothing to do with the car being mistreated in any way.

The car has never been all that smooth anyway when cold, but today just seemed much worse. Could this be a coilpack warning sign, or am I just paranoid?

I drive a diesel - there is no such thing as smooth on cold mornings *chug chug chug* sorry I can't help :(

Mine's never smooth from cold either.

Initially on starting the revs are well above the 1k mark; I only move off once the revs have dropped to around 1k and below. All is fine then. I think it's just "sorting itself out".

Driving off before then I experience similar symptoms that you described.......a hesitant/stuttering kind of delivery (??).

Cheers.

Adrian.

Yes I can confirm my RS does this too , but only *just* after its been started and driven off , after ive driven more than 3 or 4 mins , it never reoccurs. If this becomes persistant it *may* point to a coilpack crying enough!

Mine does it on cold mornings too, seems hesitant, a couple of shudders, within a minute or two it's gone. Just a quirk I guess.

Aha - another similarity with the Impreza - they're obviously more closely related than we think !

Seems to be on gentle, part throttle as well which is exactly like the Impreza.

As above - not a fault just a trait (emissions ??)

I assume the slight increase in revs on startup is just the automatic choke? maybe preventing the engine stalling itself on the normal tickover, by just blipping the revs a little? I must admit although my car sounds nasty on cold mornings (chug, chug, chug as above) - It never alters the tickover level. This could be because its a lot harder to stall a diesel, than a petrol. I've made many attempts to try and stall my car but the thing just won't do it! - pulling away in 2nd, or accelerating from 20mph in 4th is no trouble (slow though) I don't know the torque of the TDI, but I imagine its bloody high.

ALL diesels sound noisy when cold, ALWAYS. And ALL diesels lack their normal power when cold. A cold diesel is not happy!

Any minor inperfection with the fuel could have caused the roughness, probably contaminated with water. See what happens when you put a fresh tank of fuel. Also if the car started OK and the time between starting and making your usual left turn was more than 10 seconds your coils are almost definately not to blame.

Also note diesel engines do not have a choke, they may however have a little excess fuel delivered when cold.

Jim.

The petrol engine trait is definitely ECU related - minor but it does do it. The Impreza same but much worse unless you revved 'through' it.

The trouble with diesels is that they are so thermally efficient that they take ages to warm up from cold so this will exaggerate things that pass quickly in petrol-engined cars. Unless you have one of those engine preheaters like on some Merc CDis. Always fancied one on my Audi but about

Diesels are nearly as efficient when cold as they are when they are hot.

The reason a diesel engine is noisier when cold is because the ignition delay is longer.

During the period before ignition of the fuel, extra chemical reactions take place which cause rapid pressure increases in the cylinder. This is the knocking sound you get and is therfore noisier when cold.

Did you know the VW group TDi is the most thermally efficient internal combustion engine in production?

PD TDis come with an engine preheater as standard. Still takes a while to warm up though! :1:

Guys mine does this a lot as well.

The difference is that mine is fairly constant, hence a trip to Forward Motors tomorrow to see what prob is. It seems to be very lumpy when cold and then when it warms up, if I am sitting at lights the tacho is going up and down between 600-1200 Rpm, with the car sort of lumpy as if it is overunning slightly.

The worse thing really is a constant hesitation when changing down between 2nd & 3rd and up again. It feels a bit like someone is pulling the handbrake on and off very slightly. Bloody annoying I can tell you.

Well hopefully by the time the meet is on it will be sorted mate!

I actually notice this cold start thing too. It is only for the first 100 meters or so, but going from 1st to 2nd it feels like it isn't getting enough petrol to run smoothly. And it isn't on every morning, but this morning (very moist outside) it did, and on a few previous occasions.

Q.

the problem on both petrol and diesel engines is fuel managment problems 1. the diesel engine is noisy when cold is because it has a cold start procedure that firstly injects more fuel and second advances the diesel pump timming until warm. petrol engine are similar but petrol engines just inject more fuel when cold + rasies engine revs. both have no auto chokes.

My RS dosn't suffer from any hesitation or excesive noise always been the same from new.

Interesting explaination Big K - always enjoy your posts.

This is probably a silly question but...what's the difference between the ECU injecting more

fuel and an auto choke?

As in, why isn't the part of the ECU which controls pumping more fuel in when cold called

an auto choke?

I'm probably going to feel really stupid once I know the answer...

Rob.