Puff of smoke on start-up - 1.9 ARL motor

[BenG]

I've noticed that, while my car starts almost immediately from cold, there's often a puff of smoke from the tailpipe which clears after a second or so. This afternoon leaving work it looked a bit blue, like oil smoke.

The car doesn't smoke noticeably in normal driving, drives fine and has only covered 58k miles with a FSH.

A mate of mine said his old Golf Mk4 with the ARL engine did the same.

Anyone have any idea if this is a problem or normal??

 

[Muttley]

Mine sometimes produces a visible puff of smoke and always produces that sooty smell, but only on startup. I've got no fault codes, no noticable effects on performance when driving.

I do know that I have a dodgy pancake pipe (previous owner hit something that trashed the undertray and dinged the pipe, breaking off the pipe forward of the clip on one side). The extra movement of the engine at startup may be enough to loosen the joint off a bit. I've got a replacement pipe but not been able to clear a day to fix it yet.

 

[bruceR]

Ben, this is normal for these TDI's.
Best to give it a good dose of right foot once a week to keep the soot build up to a minimum.
I noticed a reduction in the amount of smoke from mine now the EGR delete pipe is fitted.

 

[BenG]

Mine sometimes produces a visible puff of smoke and always produces that sooty smell, but only on startup. I've got no fault codes, no noticable effects on performance when driving.

I do know that I have a dodgy pancake pipe (previous owner hit something that trashed the undertray and dinged the pipe, breaking off the pipe forward of the clip on one side). The extra movement of the engine at startup may be enough to loosen the joint off a bit. I've got a replacement pipe but not been able to clear a day to fix it yet.

I noticed my rubber pressure pipe from the pancake pipe to the intercooler is slightly loose at the joint, so the joint may be leaking slightly. I can't think this would affect starting, though, as the turbo isn't really pressurising the pipework at idle.

A new one is costing £60 Why couldn't VW just use a simple rubber hose like everyone else??

 

[James_R]

carl from revo once posted about this strange occurance explaining that because of the shape of the pd piston it allows a small amount of cool unburned fuel to pool in the combustion pot upon initial cranking which is quickly explelled once the engine is started, leaving the exhaust system as momentary white smoke.

sounds plausible to me.

 

[BenG]

Interesting, though it's odd that excess fuel would end up in the combustion chamber at all given the injectors would presumably be atomising it very finely to ensure it all burns. Also, turning the engine off while hot would presumably vaporise any residual fuel?

Doesn't really matter anyway as the car runs fine, just looks like my motor's knackered when starting it up

 

[snk]

the engine starts fast in cold temperatures because the ecu injects fuel in excess, thats why it make the ball of smoke.

 

[BenG]

It does start very fast, but is puffing out smoke at the moment when the ambient temperatures are a balmy (for Aberdeen) 15°C or so.