Did you repair the wires?

 

When I had a misfire on my 960, the wires were simply coming out of the back of the plug connector. Make sure the wires are plugged in the back of the connector good so it makes good connection to the back of the coil pack.

 

"Did you repair the wires?"

[Hangs head and kicks at the dirt, embarrassed] Well, no, but...

My wires look exactly like the picture in RSPI's post. I confirmed that the connectors were solidly on the posts of the coil. I got the (weird) voltage reading of 16.5V on the misfiring cylinder, but I also got the same reading on the cylinders that are working properly.

So while the wires aren't exactly as the Volvo gods intended them to be they don't seem to be the source of the issue.

But...

Everything you told me about the car was correct. I was especially impressed with the leaky PS hose...you nailed that. So where do I cut the wire to splice the new end on? Where is it most likely that the short is happening?

And just in case...

One thing I didn't check was the connector at the power stage. Could the problem lie there? Could the problem be a result of a faulty fuel injector? Could the problem be further down the line from the power stage?

 

I would check Wire # 1 from the coil to the Power stage. Any brittle part, any exposed wire, I would repair and heat-shrink.

What's the voltage on the battery posts?

 

I'm not sure this is a good test to see if the problem follows. Unfortionately, I have heard several people with these cars complain about burnt valves.

I would push some super unleaded in it (91+ octane) and a bottle of Lucas Injector cleaner and see what happens after a tank of gas.

 

Just went through the thread again and can not see where/if I have given you my octane lecture. The I6 that Volvo has in the 960's are pretty high compression motors and do require 91+ octane. Running 87 causes the motor to use the knock sensor system to avoid knock. Adjusting timing to offset low octane gas.

There is a chance that you have a burnt valve or something that may be causing low compression on that cylinder.

 

Henry- I haven't gotten a chance to get under the hood again to check the battery voltage. I wasn't feeling well Sunday.

rspi- The plug had very normal wear, (which shows it was operational) and looks like it's in great condition with plenty to go before it has to be replaced. Would there be evidence of a burnt valve on the plug? How can I understand if a burnt valve is the issue? Will I have to remove the valve cover?

I'll get my daughter to put 91 octane and the injector cleaner in on her next fill up.

 

there is no "valve cover" as we would normally know them....you would have to remove the head to flip it over and actually put eyes on the valves.....im i the process of replacing the head on mine ....lost one of the number 3 exhaust valves .....i did a compression test first and found 0 on the gauge but all others were perfect, telling me the head gasket should be ok....we then put air in the spark plug hole while we bumped the motor over .....no air at the intake then air at the intake ......telling me the intake valves are opening and closing ....the exhaust however had a little air all the time and alot when the valves were open ....telling me that the valve isn't seating all the way.......we were hopeing for carbon build up but thus far have had no luck in freeing it up, so we are now reserved to a burnt valve, collapsed spring or burnt seat ....not really sure but we know theres a problem with that valve for sure....i found good used head and im actually shopping for gaskets and head bolts right now......hope this helps some one