2004 XC70 Auto, 182 K Miles, Misfiring Topic is solved

[E Showell]

So Ruby Red picked up a miss a few days after extended torrential rains and a long high speed highway run.

I've put 20K on the car since acquisition last New Year's eve. I had wanted to change the spark plugs from day one, but couldn't get the coil boot on cylinder #1 off to access the plug. That shut down the whole operation.

Now, I am getting the following codes per VIDA/DICE

-- ECM 3503, misfire at least one cylinder -- emission agitation
-- ECM 3543, misfire cylinder 4 -- emission agitation
-- ECM 3553, misfire cylinder 5 -- start up
-- ECM 130A, air intake leakage

My belief is the coil packs may be original. I had planned on refreshing them at some point. Looks like that point is now.

Could these codes be caused by faulty plugs/coils (except the last one -- air leakage)?

[abscate]

Check the date codes on them, I bet they say 04-xx

Time for new ones and new Plugs. I am a fan of cheap Bosch plugs or Volvo from FCP as I like having them out of the head every 30k miles and new ones in.

[E Showell]

I only use Volvo plugs. And I get a lifetime warranty from a certain supplier with a three letter name starting with "F" who is also a supporter of this site, so what's not to like. . .

[SuperHerman]

Start with the air leak. If that doesn't solve your issues, swap coils 4 and 5 to other locations - see if codes follow.

Wouldn't hurt to change the plugs if they are old as you will have four coils off - so you are one away.

[- Pete -]

Pretty sure you can get just a replacement boot. I've had to tear them off before, almost like they had been siliconed onto the plug type deal. Every time it's happened that's been the dead coil. Just gotta use a pick to tear the remaining boot a bit & long needle nose to extract the bits of rubber. Compressed air is nice to blow out the pocket before you unwind the plugs. I'd start with #1 so you don't have 4 gaping holes for rubber bits to fall down in when you use compressed air.

[RickHaleParker]

Switch coil packs 1&2 with 5&6 clear codes. If the misfiring moves to 1&2 it is the coils.

Do a compression test. Misfiring on adjacent cylinders can be cause by a leaking head gasket, which lets pressure flow between the cylinders.

[Georgeandkira]

That wasn't the smoothest running engine I've ever heard Ev. If you want help, speak up as it's only getting colder.
Got compression tester?

[abscate]

Keep it simple. Plugs and coils will fix it.

[E Showell]

I borrowed Mr. Occam's razor, replaced all coils and plugs & Ruby Red is purring like a kitten. Coil packs had Volvo brand markings and a date code from Week 13 of '04, so original to the car. I'm not going to complain about getting 182 K miles out of coils and I wanted to change the plugs 20k ago, so . . . Light coating of antiseize on the plug threads and dielectric grease up top.

[abscate]

Now you have a spare for each Volvo including Livia, and a cool Volvo paperweight too.