H all,

On the way home from work today, my engine light started to flash and then stay on. Car also started running very badly. I took it ot Autozone and this code popped up 0408 Cylinder #4 misfiring.

I changed out spark plug with no success on curing rough idle. I did not find the coil sets for this vehicle at local auto parts store. So I couldn't change the coils. Anyway upon removing cover to access plugs I noticed there was oil around the boots of the plug and also some on the thread of the plugs. There is also some oil on the ouside of cover to the right of the oil cap. Any idea where the oil might be coming from? No oil leaks on ground and seldom only notice smoke coming from tailpipe. Mileage is just over 172,000.

Thanks

 

Oil is coming trough oil cap. Is it smoking from dipstick tube ? Clogged PVC probably.
Also check compression in that cylinder.
edit:
code P0408 is EGR Flow Sensor B Circuit High Input

 

Thanks Blackbrick for the quick reply--Maybe I was worng on the error code # as the code read misfiring on cylinder #4. I am not mechanical savvy so I have to take the word of the autozone rep and assume that it a tune up is needed.

I have two concerns here:
#1 clearing the code.
#2 diagnosing where the oil came from. I hope it is just the PCV as this seems to be a lot less expensive than pistons or something else of that nature. I did not check the dipstick. I think that htis might be out of my realm of capabilities to repair. I may have to take it to a mechanic. Any other insight that you might be able to provide as possible culprits of th oil would be greatly appreciated.

Thank you

 

I believe your code is PO304 - misfiring in cylinder # 4
I am not expert either just general knowledge.
#1 autozone can clear your code. You can tell them that you did tuneup and want to see if code will come back.
#2 If smoke comes out of dipstick tube, PVC is cogged and pressurizes engine and oil is trying to escape trough oil filler cap ( new filler cap seal could help but eventually oil will find other way to escape) If you search 850 section of this forum you could find more on this issue which is common for Volvo 850.
Here is link DIY PVC for 850 and early S70 V70 http://www.lakesidedp.com/uploadpics/pcv/
And hope it's not internal problem

 

Hi Blackbrick,

I changed the coil and problem is gone as far as the misfiring. I got the car up to temp and did not see any smoke coming from the dipstick so does that mean that the PCV is not clogged? Also I taked to my mechanic and he recommended that I have a valve cover gasket installed. According to his computer that is a 6 hour job. Does anyone know if that is about right? At what point do I have the valve cover gasket changed?

Thanks for your help

 

Your mechanic obviously doesn't work on too many volvos... there IS no valve cover on these cars. It's a cam cover, and the cam bearings are part of it. Yes, it takes a lot of time to replace, but it probably doesn't need it. When you get oil under the spark plug cover, it's usually the oil cap seal. FCPGroton (add a .com to that for the site!) has them for cheap, and it's a 2 second job you can do yourself. Very common problem on these cars.

 

Agree with Carrots.
You could find filler cap seal or whole filer cap in Autozone or Walmart.

 

Thanks for the replies. I really do appreciate it.