hi all, new to the forum.
i've tried doing searches on here and even watch youtube vids and other forums but can't find anything solid for 06+ S40's on ignition coils.

my car seems to have very mild/minor misfires during idle and stutters/sputters during hard acceleration. my first thought was to replace the FPS, which i did using the amazon bosch sensor, it helped a bit with the acceleration but there is still a hesistant stutter when accelerating hard.

so now i'm thinking it's the ignition coils cause the misfires are still there when idling.

my question is, how can i tell which coil is misfiring since i don't have any CEL codes and i don't want to replace all 5 since the coils are quite costly.

and are there any DIY threads on replacing the ignition coils for the 06+ S40 models? cause from what i know the <05 models have coil packs as opposed to individual coils per cylinder.

 

how many miles on the car? If you are at 100K+ on the originals, you may want to just replace them all and go worry free for the next 100K. You should be able to buy a single coil and just move around until you see some improvements (perhaps an odd colored plug can give you a clue?). You may also want to see if there are any codes stored that didn't trigger the CEL.

 

The 2000 - 2004.5 models had coils over 2 of the plugs with wires running from each coil to another plug. It was just firing 2 of the plus at a time. The 5cyl S40s have the same type coil over each plug. Replacement is easy, just pop the cover and each coil has a power/signal connection and a 10mm bolt (they were 10's on the early S40's) Take both of those off and the coil pulls straight off.

When my coils went bad I had a miss for quite a while before any CEL came on. Also if you pull the coil you might be able to see a fine crack running the length of the plastic post. That is whay mine had, and they were shorting out to the head once they got hot and the plastic opened up a bit. I tried wrapping the posts with a thick layer of electrical tape but that didn't work for very long.

I would also replace them all, if ones bad the others are close behind. They are what, $40 each for aftermarkets??? Ouch, but hey, you own a Volvo so get used to it lol/jk