Volvo 960 missing ciylinder

head gasket blown or warped heador cracked head on engine

Firing order is 1, 5, 3, 6, 2, 4. Number 1 cylinder is up front. Why would you need the firing order, this engine does not have plug wires, each plug has its own coil pack, each coil pack is controlled by the computer.

the engine oil is coming from the side of the upper and lower cylinder block. it does not use a casket but a special glue. The pressure in the engine is high, so do have a check with the PCV, located below the inlet manifold. The rubber hose should be replaced too. It may be blocked. Wet spark plugs will cause the misfiring.

Remove the black cover ( wording VOLVO and 24 Valves) on the upper cylinder block by unscrewing the 6 small screws. But extra careful and removing the individual ignition coil for each spark plug as the wire hareness may be bristle and will break away from the socket.

Spark Plug removal procedure & gap info...

• Remove spark plug access cover. (Black cover on top of engine.)
• Once you have the black plastic cover off, number the coil packs with a magic marker 1 - 6 front to back so you can correctly replace them.
• Coil packs are held in with a pair of 10mm bolts (A and B in the illustration. Later 960s have only one bolt at A).
• Once you have the bolts out the pack should just pull out. A little twisting may help as there is an "O" ring seal at the top of the valve cover and a big boot at the spark plug.
• Remove coils from spark plugs. Do NOT disconnect coil wires. (VERY IMPORTANT)
• Inspect the condition of the wiring going to the coil pack. Look for crumbled insulation or charring. See 960 FAQ file for information on failing engine wiring harnesses.
• If you have comprssed air blow out the plug cavity before you take the plug out. As an alternative use a vacuum cleaner and brush to clean any "stuff" out of the hole to avoid having it fall into the cylinder.
• Remove spark plugs. Use a good quality, rubber insulated spark plug socket. Once they are unscrewed, you have to haul them up out of the hole.
• Check and adjust spark plug gap to: 0.030" (.75 mm)
• Install clean, "un-oiled", spark plugs and torque to: 18 ft. lbs .
• Refit ignition coils.
• Reinstall spark plug access cover.

• narrow-gap risk: spark might be too weak/small to ignite fuel;
• narrow-gap benefit: plug always fires on each cycle;
• wide-gap risk: plug might not fire, or miss at high speeds;
• wide-gap benefit: spark is strong for a clean burn.

the only way to check ECU is to check it with a known GOOD----ONE

Check the fuel pressure and injectors also, try adding injector cleaner to your gas for the next three gas tanks. Start with that, Good luck and hope this helps, keep me posted. 

Check the codes, if there is a misfire it may tell you which cylinder(s) is misfiring. The coils fail, and make sure to use Volvo spark plugs!

http://repairpal.com/volvo-s80-2002

Possible intake gasket leak causing a misfire, or plugs or coil causing a misfire. each cylinder has its own coil. You can hear the vaccuum leak with your ears under hood if gasket is bad. Check eng codes at advance auto prob for free. If it has misfire codes only, prob coil or plugs. If misfire with fuel trim, prob gasket.

Remove the torx 30 screws that hold the plastic cover on the top of the engine,then you will find 10mm bolts holding coils to cyl head,remove bolts,lift coils out of spark plug holes,remove and replace spark plugs