Rev Counter Going Crazy At Idle......

[Daz1978]

Hey just recently my rev counter needle started going crazy at idle speed it would jump fom the 1k mark up to about the 4k and back down constantly at idle( a bit like its reacting to the music from the radio :-) ), the weird thing is when your accelerating or driving normally in any gear the reading is perfectly stable, the engine is not randomly reving just running normal but it has developed the odd cough any idea if these 2 problems are related?

[Daz1978]

Update: now the car is running like a pig when is really damp and gets better when it warms up, has to be something to do with the high tension from the coil?

[Raistlin]

Faulty Battery

[Daz1978]

Battery???

Latest update I removed and cleaned the contacts on the distributor cap and rotor, this fixed the issue for a day till it rained and the fault came back again.

Leaning on this I managed to track down an original jap replacement part from a trusted motor factor only €14 ! last one hed had ha ha not surprising , but the cars been running like a dream since even after a wet morning start. The weird thing is this has fixed both the cough and the crazy RPM dial issues, fingers crossed she stays fixed............