Ok, bare with me guys. Not only am I new to Volvo's (have only owned mine for about 6 months) but I really don't know much about cars in general.

I noticed about a week or so ago that the car was lagging a little. It still cranked fine but didn't have as much get-up-and-go as it should have, especially around the 55 - 65 mph range. The check engine light also came on. I took it to autozone who hooked it up and told me I had a misfire in cylinder 4. I was told by the guy at the store that it was more than likely just the spark plugs so I went ahead and bought a set - he recommended Bosch.

I put the four new spark plugs in but the problem has not gone away, it's just changed a little. The car is idling really rough - at times it almost sounds like it'll cut off (although I noticed it's a little better if it's in "park" rather than in "drive" while idling). When driving it actually seems to be doing ok - a little rough now and again, but it actually appears to be accelerating a little better than before. I read on here that it might be the coil pack that needs replaced so I went ahead and ordered one as well as ordering new spark plug wires - still waiting on both orders to arrive. Anyway, while I was looking at the motor I noticed the wires going into the coil pack (just where they go into the little harness) are brittle and cracking. They really look like they need replaced - do you think this could have been the problem all along?? I've tried finding new wires for the coil pack online but can't locate them. Where can I get them?? I know the volvo dealership would surely have them, but I was hoping to avoid the expense of visiting the dealership. Also, how difficult will it be to replace the wires?? I really don't have the money to pay someone right now but like I said at the start, I'm not the most car savvy person in the world.

P.S. I also didn't check the "gap" of the new spark plugs - does anyone know what it should be and would this possibly cause the problem I'm having??

 

I had this same misfire problem on a 2001 S40. It did not get resolved until I actually bought Volvo spark plugs from the dealership. This is after replacing both coil packs and all new wires.

 

+1 on the OEM plugs.
I had issues with aftermarket plugs on both my P2 S40 T5 and my S60R. In both cases, OEM plugs fixed my misfires.

 

I have similar problems. changed spark plugs - oem but not from dealer. then, i changed the Ignition Coil.

Ignition Coil in the ones that is sitting on top of spark plugs. s40 needs 2 of them. i bought my ignition coil from autozone. i think it is $30 each.

also, when you close the engine cover, be careful. do not let the wires got pinched by screws ( attaching cover to engine). Engine is very hot and it will burned the wires and you will have another problem.

If you are in Charlotte, nc area, i can even stopped by and help you out.

Best of luck!

 

Thanks for all the input guys - and especially to bigvolvo for your offer of help - but I think I figured it out. Putting on the new wires and ignition coils didn't make any difference to the problem so I figured it was going to have to be the spark plugs. Before running down to the dealership and dropping the best part of another $50 I decided to have another look at the Bosch plugs I'd already installed.

Like I said in my initial post I didn't think to check the "gap" of the spark plugs before putting them in. I went back and pulled them out and sure enough 3 of the 4 where way off - one of them didn't have a gap at all. I adjusted them to the correct setting (0.028) and sure enough the car is running smoothly again. Went for a little drive - about 60 mile round trip - and didn't have any problems.

Kind of annoyed at myself for spending the money on the wires/coils when it looks like I didn't need to, but I guess it can't do any harm - at least I know it's done and can get back to to just enjoying the smooth ride now!

 

Congrats on the fix.