Lotus Elan

Misfire when cooling fan starts

PostPost by: Diving Duck » Sat Oct 22, 2016 6:32 pm

I have an interesting problem with my 72 Sprint fitted with Luminition. It runs perfectly well until the temp hits 90c when a misfire begins. I thought it was associated with temperature until I realised that this was the temp that the twin electric fans cut in. As soon as the temp dropped enough for the fans to stop the misfire cleared. I experimented a bit and found that the misfire could be caused by blowing the airhorns or other high electrical power usage.
I have checked electrical connections and earths and can improve things slightly but the misfire is still there.
Any ideas
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PostPost by: Diving Duck » Sat Oct 22, 2016 8:01 pm

Forgot to mention that the rev counter starts swinging when the misfire starts which I think indicates an electrical problem.
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PostPost by: john.p.clegg » Sat Oct 22, 2016 8:15 pm

Probably the Luminition is fed off the same circuit as the air horns/fans and as they come on the voltage at that point drops sufficiently to cause mis-operation....a good voltmeter will prove whether this is the case or not.

The cure is to clean all the connections in the circuit ( battery and earth ) or re-wire just the luminition supply and earth or the circuit for the horns/fans.

John :wink:
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