rough idle and backfire

[M98318ti]

i have a 1998 318 ti it has a rough idle all the time and will backfire sometimes any ideas

thanks in advance

[2ndBimmer]

What octaine gas are you putting it it? From my experience anything under 91/92 will make the car uneasy.

[bimmerboi318]

is the check engine light on? a bad sensor (crank, cam, temperature, etc...) can do this easily. if the light is on get it checked. and yes the octane of the gas can affect the running of the engine easily. a higher octane is not always better. the higher the octane, the harder it is for the gas to evaporate making it harder to burn. especially if there are alot of miles on the engine and carbon deposits.

[318tibimmer]

When was the last time you changed your spark plugs? Maybe try that