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Despite 4 visits to both to our local independant mechanics, and the Vauxhall main dealership, no-one has been able to determine why our 16V M reg Astra is mis-firing on Cylinder One. The coil has been changed, leads plugs etc swapped from cylinder to cylinder, but always it is Cylinder One that is at fault. Oddly, it fires perfectly when the engine first starts, but after 10 to 15 seconds the problems start. Any ideas anyone?
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Sorry but what makes you say its no/1 cylinder causing the prob.or do you mean one of the cylinders is mis-firing.could be a vacuum pipe leak on one of the pipes on inlet manifold close to cylinder affected.just a thought?
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once had a diesel ford engine with a problem running ok when cold and rough when hot it turned out that a valve stem had picked up a bit of swarf and scraped valve stem causing it to stick slightly when hot .can you run it with the rocker lid of and see if valves working ok when hot ?a slightly bent valve could possibly cause this.might be worth a look.
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can you run it with the rocker lid of ....
You could run it with the rocker cover off, but it would make one hell of a mess. If you only remove the oil filler cap on these engines it can go everywhere.
A compression test might show a leaky valve. Do the test with a stone cold engine, then repeat with a warm engine. Do all 4 cylinders (cold, then hot) and compare the results.
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it wont make much mess as for the short time it would need to run any splash can be caught with a rag or a bit of card board with a hole cut in it to go round the head,you dont need to rev its nuts of.you can also check valves by turning engine by hand .check tappets whilst in there.Dave it wont blow as bad as taking the filler cap of as it has more room to vent and not trying to put the back pressure through a small filler hole.compression test will tell if theres a problem but wont tell which valve (if thats the problem)as a visual check would.
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Thank you for all of this. I haven't the first idea what most of this is about .... the extent of my mechanical knowledge is being able to determine that there is an engine under the bonnet!
It isn't just one of the cylinders that misfires - it's always the same one. But it's back to the main dealer this week with all these ideas printed out so with any chance I'll be driving on all 4 cylinders by the weekend!
Keep them coming!
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Sorry ... I forgot to add that a compression test has also been done apparently not showing anything!
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Apart from what Andrew said could still be an air leak on inlet manifold ie pipe split.?
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Either something mechanical like an hydraulic tappet (lifter) pumping up and holding a valve open or an electrical problem with the injector or the ignition coil pack, may also be the inlet manifold gasket but my money is on a sticking valve/lifter. If it is a lifter a very long engine flush followed by an oil change (semi synthetic 10w/40) with a bottle of Dr Fortes' Top-End-Treatment may cure.
Andrew
Simplicate and add lightness!!
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how about checking the simple stuff first????
does it use any water - oil. how much fuel does it use - try using injector cleaner.
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