Is it possible -without a scan- to know if one of my spark plug multipliers needs to be changed?

 

It is way easier with a scan tool, you can move the coil packs around and your misfire code, if bad, should change cylinders.

 

what do u mean by moving around the coil packs?

 

If you have a misfire on say cylinder 1, if you swapped out coil pack 1 with 2 and the misfire moves from 1 to 2, then you know it’s that coil pack.

 

Sorry, but I'm not familiar with the term "spark plug multipliers"? What is this?

 

He means coil packs, the term got lost in translation.

 

Ah, thanks.

 

sorry about the misunderstanding... it was my fault

 

Not at all! I asked out of curiosity.

And, back to your original question... if you are getting a rough idle, or any kind of misfire, your coils and plugs should probably be replaced. Also, best to replace them as a set, rather than just one or two at a time. I would also consider the coils and plugs to be maintenance items to be replaced every 40-50k miles.

 

Coils are super simple, like the other guy said, swap your coils and rescan your codes. (most parts stores will have a scanner you can use in their parking lot) once you confirm its a coil, replace said coil.
I have often replaced just one coil at a time as they go bad, sure its recommended to do all 4 and plugs at the same time, but never had an issue with doing one at a time... and I just started doing them on mine. (original owner never did them) and I have 250k km on my original spark plugs (swapped out now since i did timing chain and figured why not) but coils, ive been doing em 1 at a time as they fail. (2 outta 4 so far, other 2 are going strong).