hello all. I have a 2000 w reg bravo 1.2 16 valve (80sx) its recently started miss firing. I have changed plugs, leads and coil but still the same. I have ran some stp throught the petrol tank but it still miss fires. It sounds like its running on 3 cylinders and if i remove plug lead 2 or 3 it makes no difference. any advice please would be appreciated. I am a boiler engineer and work for a manufacturer so anyone wishing any knowledge on them fire away.

when removing 2 HT leads makes no difference to running it almost always means a coil pack failure. its easy to change (10 mins), but they arent cheap. i'd get one from a scrapyard, it'll be much cheaper (£10)

i have changed the coil pack. i tried the one off my brothers 1.4 12v which is exactly the same and even tried mine on his. that made no difference and his ran perfect with mine on. any more responses please?

Have you had a diagnostic check on it?

ok, so the coil, plugs and leads can be assumed to be working fine.

other possible causes i can think of from the '2 lead' symptom are;

the 2 cylinders where no difference is noticed have blocked or dead injectors (not very likely on a 1.2)

the 2 cylinders where no difference is noticed have poor compression due to valve blockage or damage or piston ring wear (compression test will help identify such a problem but i doubt its the cause)

the crankshaft position sensor is telling the ecu to fire the plugs out of sync with the pistons, meaning only 2 luckily spark at the right time due to the 'wasted spark' system of your coil (i think this is possible, a diagnostics "should" identify it)

the LT wiring to the coil may be damaged causing a loss of power supply to one of the 2 coils, meaning 2 sparkplugs dont recieve any power (you can visibly check each plug is sparking to rule out this, if the suspect 2 dont get a spark at all and the coil is known to be good it probably means the LT wiring to the coil is damaged)

have a play with these ideas and let us know how you get on

i have it booked in to fiat for diagnostics on sat morning. I will let u all know the outcome of this. I do know the plugs are firing but not if they are in sync so the thing about the crankshaft sensor could be plausible im hopeng so because up till now it has been the most reliable fiat i have ever had.
Many thanx guys will let u know at weekend.

another quick check, is the timing belt still tight? if the tension isnt right it may have slipped a few teeth, meaning the sparkplugs are firing ok but the valves aren't in synch with the pistons. that could cause the same problem, and its not uncommon on many 1.2 fiats so i dont see why the bravo should be different.

that wouldnt be spotted by a diagnostics so check the belt before you go. it should be tight.

I have just got back from fiat with it. The mechanic there reckons the head gasket has gone as nothing shown up on the diagnostic and he had some gadget in the radiator showing fuel gasses in the water. Im still not 100% convinced but thats the avenue i have to take. Its had a new cambelt at 60k (14k ago) and i dont think its jumped a tooth on the belt as whoever did it put white dots on to line it up and they fell in line. Any1 no of a good garage in or around nottinghm derby where i can get it done, or how hard is it to change? i am no novice when it comes to doing this sort of work but am a little worried about the belt not bein right when i put it back together and also will i need a head skim as there is no water mixing with oil? Or even how hard is the engine to swap ive been quoted £921 (yes i know RIP off) from fiat for the head to be done. £350 for a second hand engine mileage unknown.

if you only want a head gasket change, most independant garages will do it for about £150-250.

you can do it yourself easily (if you ever owned a rover k-series you'd have done it every year), just check in haynes to see how easy it is...
BUT if you havent got the right tools and a good place to work it will end up been a bodge job, so dont do it unless you can do it properly.

and i always advise a head skim when changing the head gasket, and a pressure test, just in case, you'd hate to put it back together and then find out the head has a crack or is warped or there is still a gasket leak due to a bad mating surface between block and head.

a compression test will show a head gasket leak, but a gas analyser in the coolant is more reliable so maybe fiat are correct.

Got car back on monday, head gasket was blown between ports 2 and 3. he skimmed the head and said it had been done before and not very well. cost me £310 with new cam belt new oil and filter. It sounds and runs better than ever just have to watch the mpg now see if there better normally 110 miles to a tenner. I do think its appalling that a 6 year old car with 70k on the clock has had head job twice. My mate has a MG rover, he loves it and never had probs with head gasket on that.

daren6002 said:

My mate has a MG rover, he loves it and never had probs with head gasket on that.

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wow, thats 2 satisfied customers, not bad. only 8 away from double figures. still doesnt make me want to own one. if it wasnt for the head gasket issue i'd have an mg right now no question. but i must have seen more than double the headgasket failures on rovers compared to all other cars put together. i feel sorry for ford, why did they buy the rights to make rovers? what a waste of money! bet they paid £10 for it.