I just had my Volvo checked out with an obd. I got the engine code p 0301 cylinder one misfire. I have changed the spark plugs. There was oil underneath the spark plug cover. I also have been getting really bad gas mileage, about 12 mpg in the city.

Also there is a major loss of power only going up hill. I have to keep my foot in the floor just to keep it at 45.

 

Did you change the plug wires, distributor cap and rotor?

 

Hi Jimmy, welcome to the forum.

What kind of car do you have? What year? Is it turbo? Do you run 91+ octane? How long have you owned the car? How many miles on the car?

 

 

I have a 96 Volvo 850. I haven't replaced the wires, cap or rotor. Would that be the reason for the oil under the spark plug cover.

 

Did you watch the 2 videos?

 

For the oil underneath the spark plug cover, replace the rubber gasket on the oil cap itself.
After I did my PCV replacement, oil was still around the spark plugs. I replaced the rubber gasket on my oil cap and the oil puddles have not return. My old
oil cap gasket disintegrated when I removed it. But still do the PCV system in conjunction with the gasket on the oil cap

 

That rubber oil cap gasket should be replaced regularly. Maybe every 2 years.

 

In regards to the oil under the spark plug, it is likely to be from the oil filler cap seal that needs to be replaced or it's the pcv system that needs service. If you changed the plugs, you should also at least check the cap and rotor, if not the wires, to complete the minor tune-up. That's the most practical approach to assure optimum performance. Although I have never let it go that long on any of my cars, I have seen plug wires with more than 100k+ miles of use on them. But, what is most essential on these models is the distributor cap and rotor. The spark plugs will outlast these 2 parts, but I always check the condition of the cap and rotor, even before checking the plugs. My current daily driver is a 98 V70 GLT with 202k miles that I've been driving for about a year now, which is very similar to your 850. You're already saving yourself some bucks by DIY. Don't be stingy and cheap with your Volvo. Give it all the love and attention it's worthy of.