[Richard L]

I think the bouncing gauge is most probably caused by induced noise and spike from the Di injectors. I believe is particularly common on the Ford focus, Mini and some VW.

The simplest solution is by slicing open a shirt section of the vinyl sleeving of the green harness near the RJ connector, pick out the white wire and cut it. It will stop the noise pollution.

Please let me know. Once the interfere is gone, you can set up the failsafe properly.