Since getting the car, it had a really bad surge at cruise. Internet wisdom pointed towards the throttle potentiometer/position sensor.
It’s an easy part to get to, and apparently they can be fixed. So following Ramon’s great guide, I got stuck in.
First step is to mark the location of the pot, so you can put it back where it came from, as it is adjustable. I didn’t have any paint pens, so just used a vivid marker.
There’s meant to be three screws holding it in, but mine only had two. Remove those, disconnect the plug and pull it out. Once on the bench, there are three really small screws holding the whole thing together.
Take them out, and it all comes apart, and the issue becomes obvious.
The metal wiper had just straight up worn right through the carbon track, meaning the readings being sent back to the ECU at that throttle position would be all over the place.
As per Ramon’s guide, the trick is to move the wiper over slightly, so that it contacts a fresh part of the track and gets a clear reading again. To do this I cut the plastic tabs off with a knife, moved the wiper slightly down, and then used superglue to hold it back in place. Hopefully it holds OK, but i’ll probably look at changing to a more modern, reliable unit when I fit the Speeduino anyway.
I reassembled the unit and refit to the car, making sure to give everything a good clean down, including the electrical connector.
A quick test drive showed that the surging is gone straight away, it pulls smoothly and even idles better now. I wont tell if its gone 100% until I get on the open road again, but with a battery that was flat, a jump pack that also needed a charge, and anywhere between “E” and 1/4 in the gas tank, I couldn’t risk going far at the moment. It’s a success so far though.
I did take a quick video though, as a follow-up.