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Jul 16, 2008 3:50 pm
Jul 16, 2008 3:50 pm
Subject: Re: Intermittent firing with my engine
Hi Peter
so it is not firing (no ignition) on one or two cylinders after 2-3 days use and a night in the garage ? or is the ignition on all cylinders always good ?
For checking the ignition I would unplug each igniton cable one after the other, there should be a drop in engine speed if the cylinder is ok. If it is not dropping on one this one is bad but it can be the ignition on this one or something else.
Other test could be to unplug the ignition cable for this bad cylinder and test the spark on a separate spark plug or using the capacitive strobe light for the test (no spark - no flash).
You donīt have any misfiring? I would assume that a sticking inlet valve gives misfiring shooting into the carbs (on a sticking outlet I am not shure what it would do).
For finding bad cylinders I also like an infrared thermometer (looking like a laser gun), you can measure temperatures very lokaly (e.g. on the exhaust manifold at each cylinder) and without touching the part.
From what you tell it seems repeatable, how do you get the engine back running well? you say cleaning the plugs?
How are the valve gaps?
If it is a sticking valve this should show in a compression test, I assume
Just some thoughts, no professional checklist
Peter
Hi Peter
so it is not firing (no ignition) on one or two cylinders after 2-3 days use and a night in the garage ? or is the ignition on all cylinders always good ?
For checking the ignition I would unplug each igniton cable one after the other, there should be a drop in engine speed if the cylinder is ok. If it is not dropping on one this one is bad but it can be the ignition on this one or something else.
Other test could be to unplug the ignition cable for this bad cylinder and test the spark on a separate spark plug or using the capacitive strobe light for the test (no spark - no flash).
You donīt have any misfiring? I would assume that a sticking inlet valve gives misfiring shooting into the carbs (on a sticking outlet I am not shure what it would do).
For finding bad cylinders I also like an infrared thermometer (looking like a laser gun), you can measure temperatures very lokaly (e.g. on the exhaust manifold at each cylinder) and without touching the part.
From what you tell it seems repeatable, how do you get the engine back running well? you say cleaning the plugs?
How are the valve gaps?
If it is a sticking valve this should show in a compression test, I assume
Just some thoughts, no professional checklist
Peter