missfirey problems would cylinderhead cause this?K4M

[CLIO-Si]

hi everybody,
as above iv got a missfire under revs and low idle which drops on clio's own accord, Car is a - 99 v reg 1.6 16v Si k4m 102k

car has been off road for a long time(prob over a year) in this year ive needed new radiator and manifold, clio has been overheated a few times and manifold sounding like a rally car as one of the 4 branches was burnt right threw.
iv replaced rad+mani and since then i have had a lumpy idle and missfire threw rev range,
ive drained and flushed coolant and oil yesterday(sunday 24th) to which its slightly helped thou still got the dut-dut-drrr-dut-dut-drrr-dut-dut on idle then once revs are on off course the drrr becomes more constant.

im thinking since its been overheated a few times maybe the head has been caused sum damage....
ive replaced my battery and was given a 063 not the 065 so unsure whether this would cause anything...
.
i took my compression tester yesterday to test cylinders thou i couldnt get a hold of the spark plug with the long sockets i had and then just got on with oil+coolant change...


kinda stuck now between sending it to garage for head treatments or investigating plugs+leads further myself.....ANY CLIOSPORT HELP WOULD BE GREAT!!

MANY THANKS

 

[CLIO-Si]

http://www.ebay.co.uk/itm/RENAULT-C..._Gen:MK+II&hash=item1c0677b36f#ht_1090wt_1037

 

[Chip-mk1]

Compression test is a good place to start, if the gasket is yielding between a couple of cylinders it could cause the sort of issues you are talking about.

 

[CLIO-Si]

yeah i need to find the right socket to get to the spark plug tried everything i had yesterday and couldn't get it with it needing a long socket

 

[Chip-mk1]

Do you not have an extension you can use? Thats all I do, normal plug socket on a long extension.

 

[Djw John]

I would suspect a pencil coil has failed, the description makes me think its running on 3 cylinders. These engines eat pencil coils!

 

[CLIO-Si]

swapped coils to ones i had changed last year as i bought a new set to see if they improved..
one spark plug was fried the rest ok so after checking all plugs and compression im started and no missfire..so all good untill i try start it from cold and it struggles again....

.... not starting and im swapping coils and plugs to try anything an nothing...so i try start it in first to move car a little bit an next turn of the key it starts...so away fior drives and all seems ok and good threw the gears...
left while had tea and a cuppy and not starting again so i dunno...