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Hi - I'm hoping someone can shed some light on an engine issue I seem to be having with my 2005 Mastercraft X2 MCX 350 hp V8.
When starting from cold the engine runs perfectly well. After approximately 20 minutes (when the engine is fully warmed up the engine starts to misfire but in quite a dramatic fashion. The engine sounds like it's missing on about 4 or 5 cyclinders, so not the usual sound of just one cyclinder missing - this is quite an alarming breakdown of something.
If we stop to idle an leave it to cool down for a moment, or even if we open the engine cover then the boat will do another 5 minutes of perfect running until it decides to shudder and misfire.
I've done the following to try and diagnose certain aspects of the ignition but I'm no mechanic:
1) Set the engine into a quick neutral idle and pull each injector connector off. Result is the engine revs slow which you would expect when losing one injector. This happens for all injectors so they seem fine.
2) Set the engine to a quick neutral idle and pull each plug lead. Again engine revs dip and this returns when the plug lead is re-attached. This happens for all 8 plugs. So the plugs seem fine.
3) If we run the boat with the engine cover held up to allow cool air into the engine bay then the issue does not occur.
So I'm assuming something is getting hot/warm and causing the issue - but I've no idea what and I don't want to start replacing expensive engine parts for the fun of it.
Anyone come across this before?
Regards
Tony
When starting from cold the engine runs perfectly well. After approximately 20 minutes (when the engine is fully warmed up the engine starts to misfire but in quite a dramatic fashion. The engine sounds like it's missing on about 4 or 5 cyclinders, so not the usual sound of just one cyclinder missing - this is quite an alarming breakdown of something.
If we stop to idle an leave it to cool down for a moment, or even if we open the engine cover then the boat will do another 5 minutes of perfect running until it decides to shudder and misfire.
I've done the following to try and diagnose certain aspects of the ignition but I'm no mechanic:
1) Set the engine into a quick neutral idle and pull each injector connector off. Result is the engine revs slow which you would expect when losing one injector. This happens for all injectors so they seem fine.
2) Set the engine to a quick neutral idle and pull each plug lead. Again engine revs dip and this returns when the plug lead is re-attached. This happens for all 8 plugs. So the plugs seem fine.
3) If we run the boat with the engine cover held up to allow cool air into the engine bay then the issue does not occur.
So I'm assuming something is getting hot/warm and causing the issue - but I've no idea what and I don't want to start replacing expensive engine parts for the fun of it.
Anyone come across this before?
Regards
Tony
Boomin'
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