Vauxhall Tigra power dips, cuts out, pain in ass

Could be ignition coil pack .Also check plugs .

http://www.ebay.co.uk/itm/BRAND-NEW-VAUXHALL-MERIVA-CORSA-1-4-1-6-16v-IGNITION-COIL-PACK-UK-FREE-POST-/271313819806

Thankyou but I'm not so sure about that - the plugs have been change (I forgot to list that)- I can undersatnd a coil failing but being electrical it cnt sus when we put the car unde load ie uphill so to me the coil pack isn't the issue - happy to be proved wrong though

One of the plug coils can break down under load causing misfire .Very , very common .

Many thanks I will search it out, is it a seal unit or can I mega it? That way I should find its weak point I'm guessing

Ooops plugs - I miss read your reply sorry

Ok, today I jumped into the engine bay and after removing the cover from the engine I discovered the cabling from the Coolant temp Sensor had been trapped under it and two of the cables were bare. I seperated and taped them up. Please note this fault occured AFTER Vauxhaul had replaced the heater matrix. When we complained they told us it was a seperate fault and we had the Lamda Sensor changed. Anyway, we have been chasing this fault which has been intermitant every since. I took the car out on a 50 mile run today and it ran as sweet as anything apart from occasionally hitting 100 degrees - at which point Jill turned heating on full and the temp feel. (this was the fix she was told to do) !!!!!! I now think when they changed the matrix they didnt have the temp set to hot and they have created an air lock?? When we parked up the expansion tank was empty, as I released the pressure the tank filled up, squeezing the water pipe over at the Coolant Temp sensor area gave no effect at the expansion tank. Anyway - return journey, after 5 mins the ECU light came on - pulled over and stopped engine, restarted but ECU light still on - drove another 40 miles - engine ran as sweet as a nut again. Stopped for half hour and drove last leg home - no ECU light car running as smooth as anything. Very very confused, and hard to fathom as Im only home at weekends atm

They should have run the car with the heater on hot as you say to allow the coolant to fully circulate .Then ran it till normal working temp , checked the fan was cutting in and topped up if required . If in doubt , bleed system .

Agreed - I will keep fingers crossed and hope she has no problems with it this week - still cant figure out why the ECU light came on earlier though - but I am hoping the damaged cables were the route of the problem and this coolant issue is just a simple one. Many thanks for your advice to date.

The coolant sensor sends a signal to the ECU in reference to what fuel engine needs i.e more fuel on cold start .If the wires were bare , they could send false info or trigger light ?

Maybe, its a strange one, the wires are taped up and were when the ECU light was on - just finished bleeding coolant system so fingers crossed - ECU light was on all the way through. The wires will have to wait until next weekend before I can correctly crimp and heat shrink - intermittant faults - don't you just love them.

Update cars running much better - coolant sorted too. BUT.... ECU light is coming on now and then - but theres no apparant issue with the engine????