2008 S60 2.5T, Misfires on cylinders 1 and 3

Post by **jonesg** » 23 May 2025, 06:31

coil is failing under load, swap #3 around and see if the fault follows the coil.

Vova585 · Post by **Vova585** » 23 May 2025, 09:16

Any chance this car was in the hands of "crafty teenager" that was trying to tune it? K&N filters, straight pipes, etc? I am scratching my head what can possibly be wrong.
Another not very expensive option is to buy a harness for ignition coils.
https://ebay.us/m/gg55uO
Vs replacing connectors for 1 and 3 ignition coils. Possibly the cracked insulation is causing short to power or short to ground. If that's not helping- advance level diagnostic with scope is you best bet.

XC70Rider · Post by **XC70Rider** » 23 May 2025, 21:45

I replaced the IGN coil harness 3 years ago. The heat under that valve cover caused the pigtail connectors and wire loom to get fragile. I had all the pigtails zip tied to the IGN coils before I replaced the harness. Instead of risk it with a new aftermarket harness I got a used harness from ERIE Volvo. No issues since installing it.

With the coils over 15 years old I threw on 5 new Volvo IGN coils I got at FCPEURO. Also traded in the 5 Volvo lifetime warrantied spark plugs.

I've kept the valve cover off since then so the heat can escape.

Check page 4 of the wiring diagram I attached.

Post by **DavidE7** » 25 May 2025, 20:44

If the simple solutions aren't finding the problem there are some more complex things to check.

My S60 had misfire codes for cylinder 1 and 3 after the PCV check valve lost its guts into cylinder 3. See the post below for the diagnostic details. Compression test will provide clues. A bohr scope view inside each cylinder will let you see any mechanical damage from something foreign getting into cylinders 1 and 3 and also allow you to rule out a leaking head gasket with coolant inside the cylinder.
viewtopic.php?t=86687&hilit=Banjo&start=30
Good luck!

professorsunshine · Post by **professorsunshine** » 29 May 2025, 12:50

Bad news. I did some more testing today with different tools. I may have gotten my numbers mixed up or something, but cylinder 3 indeed has no compression. 0, zilch. That explains most of the issues I was facing.

So now I'm moving forward with replacing the cylinder head. Can anyone tell me what cylinder heads are compatible with the 2.5T engine with VVT on both cams?

2008 S60 2.5T, Misfires on cylinders 1 and 3

Re: 2008 S60 2.5T, Misfires on cylinders 1 and 3