If the contact came off the center of the cap of course you can expect misfires. That wouldn't be there if it wasn't needed. The Engine Computers, starting with '96 models, detect which cylinder is misfiring by the position of the crankshaft when its rotational speed slows down too much between power pulses. We feel misfires because we also feel that change in rotational speed. The difference is the computer is more sensitive than you are. You are especially likely to not feel a minor misfire on a V-8 engine because there's more power pulses in a given amount of time.
Now that you have the new parts installed those diagnostic fault codes will still be in memory, and due to the severity in terms of affecting emissions, the Check Engine light most likely will still be on as soon as you start the engine. The best way to erase the codes is with a scanner. They will also erase automatically after 50 engine starts if the problems don't come back. The least desirable way is to remove the negative battery cable for half a minute but that will also delete fuel trim data and "minimum throttle" from the Engine Computer's memory. You will likely need to hold the gas pedal down 1/4" to get the engine to start and stay running as you pull up to a stop sign. Minimum throttle will be relearned when you drive at highway speed with the engine warmed up, then coast for at least seven seconds without touching the pedals.
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Wednesday, March 27th, 2013 AT 7:49 AM