Question about 1991 Cadillac DeVille
The combination of heat and missing tells me that you have an ignition problem. Warm the engine as much as possible and take a water mister and mist the exhaust manifold with the water mist at each cylinder where the exhaust comes out of the cylinder. The cylinder(s) that doesn't evaporate as quickly as all the others is the one that's missing (no combustion = no heat out the exhaust for that cylinder). The next thing to do is to pull the spark plug. examine it for dirt built up around the electrode. If it's dirty then just replace all your plugs. If the plugs look good ( not worn - no contaminates around the electrode) then suspect plug wires. If all the cylinders evaporated the water pretty much the same, then your coil wire to the distributor cap or the cap and/or rotor itself is faulty. Examine the rotor cap and rotor for thin black lines running along the inside. If you find evidence of arcing (the lines inside) then replace the cap and rotor at the same time. The data you gave though sounds more like plugs or plug wires if I were to guess... For best results you should plan on replacing plugs/wires/rotor/distributor cap at the maintenance intervals suggested in the owners manual. But now that you're having these issues you should have some kind of concrete evidence before replacing these items - that is unless you've never replaced them ever before. In which case it's high time to have replaced them.
Posted on Oct 01, 2010
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Posted on Jan 02, 2017
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