Q: Engine misfired during smog check

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My engine misfired when doing the smog check.

If your engine has a misfire then that can occur for a number of reasons. If it suddenly occurred during a smog test then something may have been knocked loose during the inspection. It is not uncommon to have a vacuum hose come loose and cause this. If it is not a hose then it may have a bad ignition coil or spark plug. The computer would need to be scanned for codes to see which cylinder is misfiring. A mechanic would use the codes to determine if one of these parts is bad and to possibly check the compression of the engine. I recommend that you have your engine misfiring issue diagnosed and repaired as soon as possible to prevent further damage.

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