Join Date: Feb 2001
Location: The Sticks of Central TX
Re: EAII engine trouble
Wanted to ask if you have oil on the plugs or is it carbon build up.
If your plugs are oil covered it is an indication of advanced engine wear. When the oil enters the combustion chamber and covers the core nose of the spark plug, the spark no longer arcs across the gap. Rather it takes the easier path to ground by tracking down the oil on the core nose. This results in a complete cylinder misfire condition. You can check for worn valve guides, valve stem seals and/or piston rings.
If your plugs are black from carbon build up indicates a rich air fuel mixture, weak ignition or wrong heat range spark plug (too cold). These carbon-based deposits are conductive, much like oil fouling, and will allow the voltage coming out of the center electrode of the spark plug to track down the core nose rather than jumping the gap. This will result in an engine misfire and further aggravate the carbon fouled condition.
Check for correct plug heat range. On fi engines, check for sticking injectors, malfunctioning cold start valves and/or circuits. Also check for correct fuel pressure specifications.
On computer controlled vehicles, the "limp home" computer mode will always result in a rich condition. Therefore, it is imperative that you check the operation and condition of the on-board computer system.
On carbureted vehicles, check choke and choke pulloff, high float level, and needle and seat condition.
On all engines, severe vacuum leaks can decrease manifold vacuum, resulting in a rich condition. Weak and/or damaged secondary ignition systems will fail to spark across the gap lowering combustion chamber temperatures and promoting carbon deposits. This condition could also result from poor cylinder compression.
Regarding the mods I will let others talk to you about it. Since I am not too familiar with EA mods.