19 replies to this topic

[Moggyton]

As they say 'oop north', "There's nowt for nowt".
When you turn the lights on you are using the engine to generate the power for all the lights, so the load on the alternator and thus on the fanbelt increases. This takes some power from the engine which then slows slightly. 200 rpm is quite a big drop, but not totally unusual.
It shows how much extra fuel is being used when driving with the lights on.

i dont think how the performance changes in mine is normal though :/

[KernowCooper]

Its the juddery bit that makes me think this could be a slight misfire?

[Moggyton]

Its the juddery bit that makes me think this could be a slight misfire?

But it would still be fine with the lights off?

[KernowCooper]

If its voltage related to the ignition yes, you'll never find it unless its tested with a meter though were just guessing. It could be something as simple as a weak coil and the voltage drop could cause a slight miss.

Pity your not in Cornwall I'd do a full electrical check for you, its the only way to find it without throwing loads of bits at it, unless you strike lucky

[Moggyton]

If its voltage related to the ignition yes, you'll never find it unless its tested with a meter though were just guessing. It could be something as simple as a weak coil and the voltage drop could cause a slight miss.

Pity your not in Cornwall I'd do a full electrical check for you, its the only way to find it without throwing loads of bits at it, unless you strike lucky

oh right, thanks