I have a 2001 1.6 k-series (EU3) Caterham and I'm having some issues with the engine misfiring due to the lambda sensor.
It seems to be a problem with the heating of the sensor. The misfire is only present at low load, at higher loads it runs fine presumably because the engine is producing enough heat to get a proper reading from the sensor. With the sensor disconnected the car also runs fine which is how I've been using it for the past year or so but I thought it was time to get to the bottom of the issue.
I have tried replacing the sensor but still have the same issue which leads me to believe it's an issue with the wiring. I then thought it could be the MFRU causing the problem but I was recently reading the article on the starter motor 'k-click' problem (another thing I need to fix) which states that the oxygen sensor relay in the MFRU is not used on a Caterham. Looking at Revilla's excellent wiring diagram and seeing as everything else is working properly then it looks like there are only two wires which could cause it. And if it's not those then it points towards an internal ECU problem?
Has anyone else had this issue? Any other ideas?