My mother has a Volvo 1997 S90 and she took it to the local auto parts store, where they put their computer on it and told her that she is getting codes that are misfires on cylinders 2 & 6. I do not believe that it is the spark plugs but rather the coil packs. How many coil packs are in this car? Are there any other issues that could relate to the car issues she is having?
This problem just started: she can start the car and it will run, it runs rough (described as spitting and sputtering) when in idle or while she is accelerating. Would like to help her fix this issue, so I am needing answers as soon as someone can get to my questions. I have read many threads on this issue, just not sure where to begin other than the coil pack. Please help! Thanks in advance!
My mother has and always will be a VOVLO LADY!!

 

I would guess coil packs as well.
Her car has 6 of them.

 

The 1st thing I would do is get a code reader. That will save you trips to the auto place. Then try this: https://volvoforums.com/forum/showpo...29&postcount=2


After that, see how it runs. If it still runs rough. If it does, you may want to swap the packs to other locations, perferably 1 at a time. If the problem follows the swap, then you know it's the packs. If it stays at the locations, then you should move to a compression test.

 

I would like to know how many miles you have on the car.
Misfiring can be due to a number of things, Spark plugs, spark plug coils, fuel injectors, bad electrical connections on the coils, ignition modules, mass aux air pump and maim computer.
I had the same problem and thru a series of checks and diagnosis (all the ones above). I replaced all parts listed above. After $1500.00 later, a compression test showed that the two misfiring cyl only holds 65psi when all the rest had twice that pressure. The misfiring was due to low compression; you might need a valve job and/or new piston rings.
Check this thread: https://volvoforums.com/forum/volvo-s90-v90-40/4-5-cyl-misfiring-45249/

 

Well, I think #1 is long gone. Other than that, it's never good to throw parts at it. Best to track down the problem before taking action. Checking the coil packs and plug ends don't cost a dime. Sorry to hear that you went so far before finding low compression.

BTW, How many miles did you have on your motor?

 

My S90 has 162k. I agree with you; I learned the hard way and I learned a lot. One think I can say is that the S90s are very simple but very smart Vehicles. I have seen S90s with 350k; these are vehicles that have been maintained by Professionals. Ignoring the Service light is what killed mine. Many mechanics always claim to know hot to fix them; they will charge less but they will kill your car.

 

I do agree with that. Most Volvo's through the 2000 models were built with the mechanic in mind. I have never owned a 2001+ model so I can't vouch for them. Very easy to work on. Oil changes are the most important thing you can do for your car. I recently switched to full synthetic in all of my cars to avoid engine wear. I know that cars, especailly older ones experience other problems but oil is my #1 thing. My 2nd concern is timing belt.