Help urgently needed - rich mixture

[Guest]

Hi I need some help urgetly with my 1986 944Turbo.
Taking it for a run last night it ran perfectly to start with. However when pressing the accelerator hard it coughed and splutered and wouldn't pull. Lifting off a little it was fine and would accelerate gently up to 100mph. Every time I tried to accelerate hard it would cough and spluter - my first thoughts were not getting enough fuel. However in the headlights of a car behind I could see clouds of black smoke.This repeated every time I accelerated hard. So I am either not burning the fuel or have an overly rich mixture.

Back home , the idle was not as smooth as usual, a bit hesitant, and blipping the throttle caused even more hesitation before it recovers. Removing the plugs showed them to be extremely black.

My conclusion is either a large air leak, far too much fuel is going in, or a sensor (possibily the temp sensor thinking its still cold and signalling the choke all the time).

Does anyone have any ideas. It has happened suddenly, implying something has failed. I know a fair bit about cars, but not all the pipes and sensors on the Porsche. I really can't afford the time or cost of replacing with new, things by trial and error.

Any help would be gratefully recived as I am going away in the car soon.

Alternativly does any one know of someone that specialises in the 944 in the Guildford area ?

 

[swright]

I have just had this very same issue mate. As soon as it came on boost it would cough and splutter and even pop from the exhaust with lots of black smoke. I thought it was ignition related so i replaced the leads and coil but it still did it!!!!


As i was looking over the many air pipes i noticed that one had come loose from its splitter. It was one round the back of the engine. I plugged it back in and all was cured[] Well almost all as i still have a judder just before the turbo spools up for some reason.

Oh and also, when i first bought the car for some unknown reason the last owner had turned the mixture screw almost all the way out!!! I turned it in and then put it on my co tester and now have an idle co reading of 0.7. So check your mixture if you can.

 

[944Turbo]

Yep check for a detached or split hose, they sometimes pop off or fail causing ich running on boost,
Tony

 

[Guest]

Thanks for the kind advice. In the end it was traced to excessive fuel pressure caused by a failed pressure relief valve at the end of the fuel rail.Replaced that, and the all seems fine now.

Thanks again for the help.