Discussion
I'm not certain, but I think that engine uses ported vacuum advance. This gives no vac advance when the throttle is closed, lots of vaccum advance when it it cracked open. If you get running problems when the throttle is closed / almost closed then check whether the timing is sensible. One way to do this is to disconnect the vac advance line at the dizzy (and block off the vac line to the manifold) so there is no vac advance at all. If that improves the behaviour, you know you're in the right area.
It could also be a worn throttle pot giving a bad signal. It seems common for them to play up around the most commonly used throttle position first, which would usually correspond to the cruise position.
It could also be a worn throttle pot giving a bad signal. It seems common for them to play up around the most commonly used throttle position first, which would usually correspond to the cruise position.
The S3C has advance/retard totally under ECU (and ignition module) control: no vacuum control other than the MAP (manifold air pressure) sensor which gives load data input to the ECU.
My bet would be a worn throttle pot. Or its wiring.
Or mechanically 'sticky' or 'jerky' throttle action, which was a big problem with mine. It needs to be really smooth...
Good luck!
My bet would be a worn throttle pot. Or its wiring.
Or mechanically 'sticky' or 'jerky' throttle action, which was a big problem with mine. It needs to be really smooth...
Good luck!
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