Strange XJ6 symptoms

[Geoffrey]

hello I'm new here, and i was hoping for some help. Our S3 1986 XJ6 has developed some strange symptoms. At a cold idle, it often shudders and cuts out. We think one of the cylinders was misfiring before, but the problem has become considerably worse. From startup until the engine is warm, it will seem to miss and cut out entirely. This can be averted if you give it plenty of gas and the problem goes away once the engine is warm. We tried replacing one of the temperature sensors in the engine, and we found one of the hoses to the vacuum sensor (for the fuel injection) was loose, but the problem persists. If any of you could shed some light on the situation, it would be much appreciated

thanks,
the Andrews family

 

[tony barnhill]

Do you have to add antifreeze often?

 

[LarryK]

Check the cold start injector and the timing relay for it. Check the air box flap to see if it is clean. Also a fuel temp sensor on fuel line. Check the vacuum hoses under the manifold and the lines on top of engine to firewall for leaks. Usually when warm , but check coil connections under rubber cover.

 

[Exotexs]

I would also wiggle and press the large "Serial" Plug connecting to the AFM, and any other electrical connection for that matter.

Ex

 

[V6MGB]

I am inclined to go with the suggestion from Larry K above.
Start with the cold start injector and the wiring to it.
If the car runs OK when warm and an extra shot of gas when cold this strongly suggests the c/s is either non functioning or in need of a service.

Cheers , Pete.

 

[Geoffrey]

Thank you everyone for the suggestions. much appreciated