Expert: Ben Deutschman - 1/19/2008

Question
hi i have a 1996 audi a4 2.8 and i changed the spark plugs but i did not change the wires but when i started it back up it start idling rough and hesistating to going at a stop light and hesistating driving and now the check engine light is on do u think i put the spark plugs in wrong or should i redo putting the spark plugs and wires in again

Answer
I'm not terribly familiar with Audis, but I would hazard a guess, that maybe a Plug Wire came apart internally, when you pulled it off of the Spark Plug. If that is the case, then you would have a rough idle, and other performance problems like those you've mentioned.  In so far as the Spark Plugs themselves are concerned, if the ones you installed, are the ones listed for the application (your car), and they're gapped correctly, then they shouldn't be causing any problems. Also, make sure you didn't inadvertently put a Spark Plug Wire on the wrong Spark Plug. Other than what I've spoken of here, I cannot think of what else may have gone wrong.