Posted by dmw 85 Euro S on 6/24/2007, 12:26 pm, in reply to "Still stumbling/bogging out" I seem to recall sometimes seeing spark plugs go bad within a few hundred miles or never. I know that at least once, I had a new plug go bad as soon as the engine warmed up after installing a new set of them. If you are using expensive plugs right now, you might consider replacing them with some cheap A/Cs just to verify that the problem isn't with the existing plugs. That's one inexpensive thing that you can replace and eliminate as a possibility. Also, make sure that you check every inch of the spark plug wires and the wire to the coil because I once had a set of wires that were less than a month old go bad because a mouse chewed on them! Also, check the inside of the distributor cap for carbon tracks or cracks. A barely visible hairline crack is all it takes! The other thing you might want to check is to make sure that all of the connectors are properly connected to the fuel injectors and that none of the wires are partially pulled out of any of them or that any of the wires could be shorting somewhere. When I've seen cars shake during acceleration, it's almost always been something in the high voltage circuit; usually wires or plugs but a faulty injector or injector wireing could do the same. Vacuum leaks tend to affect all cylindars and therefore tend to cause performance and idling issues that might make the engine run a little rough but not to the point where it shakes the car. Shaking of the car indicates one or more cylindars not firing. One other cheap thing that you might try is to put in a bottle of fuel injector cleaner. I used a bottle in my 79 Euro that was running poorly and not only did it drastically improve the performance, the fuel pump which had been noisy became silent and the transmission shifted better. It shifed better because the increased power meant that the gas pedal didn't have to be pressed as far down to go the same speed which restored the correlation between gas pedal and the tranny shifting. If you happen to have an injector that is sticking closed, that might clean it up. If all else fails, see if you can find a shop that has one of those old Sun diagnostic scopes that can display the electrical waveform for each cylindar. Keep us posted on what you try and what you find out. David
76.187.147.133
I've seen the internal resistor inside of plugs go bad. Externally, they might look fine but one could have a problem.
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