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Discussion Starter #1
My '97 1.8RT 8V has got a misfire which I cant seem to solve. It misses from startup and whilst it is idling and when you are driving below 2000rpm. Above 2000rpm it picks up and goes away. The engine also makes a kind of chirping sound at idle and low rpms.....

I've done a compression test on the engine and three cylinders are at around 140 - 150PSI which is acceptable, however one cylinder is down at 90PSI, which I am assuming is the culprit.

I have checked and changed the spark plugs which didnt solve it, I have added a valve cleaning additive to the oil incase it's a stuck valve, I've done about 500miles since that and no change.

I'm assuming its either a burnt valve or that the rings are shot but I dont know for sure, before I whip the head off to have a look, does anyone have any ideas?!?!
 

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Discussion Starter #3
Yeah, thats the conclusion I was coming to. Does anyone know if theres a surefire way I can check that before I take the head off?
 

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Put a little oil down the bore of the offending cylinder - if there is improvement in compression it's likley rings but if little or no improvement it's probably valves. Good garages can carry out what is known as a leak down test which records how quickly pressure is lost - that usually gives a better guide as to what is wrong.:)
 
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