On the Elise S1 VVC a recall installed a separate misfire detection unit following some misfire/cat fire issues on the higher performance Elise variants.
As I noted below the unit links into the standard car harness in three locations. Based on some wider research I think the unit looks at spark ionisation and lambda readings to detect the onset of misfire and then limits the rpm or cuts off the offending cylinders but how in interacts with the MEMS to cut the cylinders if misfire is detected is a mystery to me, I suspect it cuts the fuelling to the offending cylinders by intercepting the signals from the Mems unit. Details on the device are sketchy; I've dropped Lotus a note to see if anyone can shed any light on how it operates but in the current circumstances I'm not expecting a response.
If the misfire unit is triggering I would start by checking the usual electrical suspects, connectors, HT leads, plugs etc. as any of these could throw it a curve ball.
If that fails you could disconnect the unit from the car and reconnect the lambda, injection and coils to the car harness to see if it makes any difference, the car will then run as it left the factory (and in the same configuration as the MGF VVC) but obviously without the protection the system was intended to offer. At least you can rule it in or out.
If you do disconnect the unit do make sure you label what goes where
as the injection and lambda plugs are not interchangeable reducing the scope for error but the plugs to coil one and two are...…
Stuart
On the Elise S1 VVC a recall installed a separate misfire detection unit following some misfire/cat fire issues on the higher performance Elise variants.