Right got car back today (after 5 months) with 2nd new engine fitted. Just want to hopefully confirm my diagnosis. When picked car up it was randomly popping like mad so went straight back round to Nippon Spares who had put the engine in. After a bit of fiddling about they swapped the ecu temp sensor over for another one - a used one. Now the car only very occasionally pops, usually when at low revs in 2nd or 3rd gear at a roundabout for example. It never does it at high revs for example when coming off throttle having given prolonged acceleration. Based on the fact that changing the sensor for another used one has improved things am I right to assume that if I replace both the sensor and the connector with new ones this should be an end to this potential fatal (to my engine and maybe me the way I feel about the car!) problem?

Best bet would to get your car on a Conzult or datascan. Could also be o2 sensors,Coilpacks, fuel pressure regulator

The only reason why Im almost sure its the temp sensor is because it was that what was changed in front of me for another used one which resulted in a lot less popping. Also, as its only the sensor that was changed, it could be the connector. Unfortunetly, I dont have the car again until Monday afternoon because its with anglia engines (who contracted it out to Nippon Spares) as it needs to have a new MOT. I am worried about driving the car too far, in view of what happened originally (two pistons cracked due to detonation). When it happened originally the popping was when I came off full (or near full) throttle and it was on average 4 loud pops. I have to admit I was a bit negligent and allowed it to get to the stage where I was getting lots of smoke as well! I think best bet is too speak to jeff at zedworld and see when he can fit me in. If its this week (I'll be lucky!) then ill just get it over to him and hope it makes the journey. If not then ill get the sensor off him and I can get the connector from an electronics shop near me and if it dont sort it I will get it over to jeff.

Jeff should be able to sort you out tbh, broken temp sensor could explain the popping and smoke due to overfuelling if it thinks its cold all the time. I don't think duff o2 sensors could cause it but I may be wrong.