Clouds of black smoke on start-up

[craig2105]

First run out on Sunday after numerous works to improve the car. I was meeting the R19 chaps for the run up to the Cornbury House Open Day, pulled up after an uneventful commute to the meeting place, and got out for a chat while everyone assembled.

On starting up, the engine was mis-firing, but to my horror, great clouds of black smoke were pouring from the exhaust. The engine settled down to a normal idle after maybe 30 seconds, but the smoke persisted for a while. I set off anyway, and the car performed normally throughout the journey, during which it received no quarter with an Italian tune-up. Another S2 was following me on the journey and reported no smoke once the initial cloud cleared- nothing on change up either.

It repeated the smoke problem when I started up to leave Cornbury, but not to the same extent as earlier. I've parked her up, disgusted...

Any ideas chaps? I'm thinking sticky valve, broken valve spring, something like that.

 

[DivineE]

No. Black isn't so bad that's just much too much fuel. Not sure what would clear up as it heated though. What kind of a cloud are we talking and are you sure its black? Sure its not blue, what does it smell like?

 

[craig2105]

The smoke could have been dark blue I suppose. It's almost as if something is burning off, then as soon as the engine is turned off, whatever it is finds it way into the induction or exhaust system. I just hope this isn't going to be too costly...

I didn't really get much of a whiff as the wind was blowing the smoke the other way!

 

[Mike_Pollock]

Guessing its oil burning so, I'd drive it a bit, leave it 20 min, start it, stop it and check the plugs.
Have you done anything to the motor?
Check the breathers and in the air box.
Mike

 

[craig2105]

Only plugs and a new dizzy cap recently. And new centre and rear exhaust sections (Janspeed and Dansk respectively).

Bled the brakes, fitted a new/refurbished caliper nearside (earlier cries for help refer) on Saturday. The car did run between the above two but only short distances between bodyshop and garage, but it ran fine, and much better after the plugs and dizzy.

 

[DivineE]

Could you post a short vid from your phone on youtube? I know its sounds extreme but it'd really help.

 

[craig2105]

I know I should be able to do this but getting video off my phone has confounded me so far. I'll give it a go tomorrow. Just as long as nobody laughs at my car, right? []

 

[944Turbo]

Probably excess fuel was it hot or cold? would check fuel pressure and temp senders.

Tony

 

[peanut]

yep I'd go with Tony on this. If it was a valve or ring etc you wouldn't expect it to clear completely when running. Stick a 3 Bar/45psi guage on the fuel rail and test the pressure when running and also the holding pressure when switched off which should be at least 1.5 Bar after 20 mins.Likely culprets are the cold start valve and associated temp sender and the FPR or fuel damperand maybe the AFM ?