Porsche Enthusiasts Club Forum

Hello,

I have just noticed that my 1982 944 auto is lumpy when its starts from cold but is fine when its warm does anyone have a clue what has failed now on this car

Cheers

Ewan

Firstly check everything is OK such as ignition, plugs air filter etc. If it still does it then I'd suspect the idle control valve is dirty. But more likely something like knackered plugs.

Hi

I agree with Jim....it sounds like faulty ignition parts...

WHEN were the plugs , dizzy cap and rotor arm last CHANGED ??? not checked but changed ???

All the best Brett

Don't forget the leads, they so often get overlooked, and can make such a difference

I would have said it was more likely to be caused by a component of the cold start mechanism. Thats where I would start looking first. Any ignition problems would undoubtably show up occasionally when the engine was warm also

have you checked the engine temperature sensor ?

Hello

Thanks for the input guys I have changed dizzy cap plugs and air filter in the last 2 months so all is good there as well as the HT leads. Can anyone point me in the direction of the cold start mech or any other contorl valve?

Cheers Ewan

The idle control valve is under the inlet manifold & gets gummed up. Getting it out really means taking off the inlet manifold. You maybe able to remove it without but getting the pipes on is a pain.

On 86 and later cars the cold start mechanism is a separate fuel injector
On early cars like yours the ECU increases the pulses to the 4x fuel injectors when the engine is cold. It is contolled by the engine temperature sensor and the AFM.

It sound to me like your engine is not getting sufficient fuel when starting and cold which would suggest to me that the engine temperature sensor is faulty or the AFM .

Hello where is the cold start mechanism mate?

Ewan

Hello,

Thanks for the gen lads sorry to ask again where is the cold start mechanism?

Ewan

I've already said Ewan.
If you have a pre 86 car then you need to test your Engine Temperature Sensor which is on the cylinder head or block near the front . Not sure exactly on early cars.
It has 2x electrical terminals and is basically a thermostat with electrical resistance . As the engine temperature changes the electrical resistance in the sensor changes.

This change in resistance is read by the ECU which increases electrical pulses to the fuel injectors giving a rich misxture for starting.
As soon as the engine temperature gets warmer the ECU reduces the pulses and the fuel delivery is decreased.

Remove the electrical connector to the sensor and measure the resistance between the two terminals when the engine is stone cold and compare with resistance test chart here http://autorepair.about.com/library/a/1i/bl721i.htm

Then you should check your AFM (air flow meter ) http://the944.com/afm.htm