Clio 172 Cup
Hi, got a right swine of an issue with my 172 cup. It doesn't get used too often, was driving along the motorway and every now and then it would lose a cylinder, which would then come back. This progressed to full on running on two, with 2 and 3 not getting spark. Replaced coil, leads and plugs, and tried putting a spare plug on a lead and testing each output of the coil. 1 and 4 always work. 2 and 3 do not, regardless of which coil I use (new or old). Have tested injectors and compression (did that before sussing it was deffo spark). What else is there to try? A while back it wouldn't start due to dodgy earth for the ECU, which I have cleaned up and put back together. I wonder if it is related, but I can't work out how a poor earth would cause the ECU not to send a signal to the coil to fire 2 and 3. Absolutely baffled and out of ideas really, short of stabbing in the dark and replacing bits at random, I just can't work out what could actually cause this. It's already had a new crank sensor (a while back) but when that was on the way out, it was completely different symptoms, like the engine just cut out... Any help greatly appreciated, cheers!