Coil Pack Problem ?
 

Mt S80 T6 has developed a misfire over the weekend, feels like it's constantly firing on 5 of 6 cylinders. On acceleration the engine light comes on but it disappears at low rpm. A GM Technician friend of mine swears its a coil pack. If so, how do I determine which one it is, and can anyone describe in baby terms how to go about the job? $$$ Volvo $outh Africa have quoted me $400 for the job, can you believe it! Really appreciate help here!

If it was misfiring on 5 cylinders it would not be drivable. More likely 1 maybe 2 are misfiring. You need to get access to an OBDII code scanner, if it is a misfire it will give you a code of P0301 through P0306. the last number of the code tells you what cylinder is misfiring. Cylinders are ordered from left to right.

Here in the States there is an auto parts store called Autozone that will scan your car for free and an individual coil pack costs ~$60US and takes less then 10 minutes to install.

Thanks Automatic, from experience I can feel that it has only lost one cylinder. I did in fact drive it back 15 miles from where it occurred and although slow and slightly rough, the engine was otherwise fine. The roughness is there from idle all the way through the rev range. I have a friendly auto shop who has the scanner you are talking about & I'm sure for a small fee he will diagnose which one it is. It also appears that buying the pack ex works is almost the same price here in South Africa as the $60 you quoted Sateside. Thankyou so much for your advice, it has made my day.

If you have one coil bad best best is to replace all of them. This way you are not changing one out every day till they are all new.

Sir Lance, In July of last summer I had the problem you now have. I had, as automatic suggested, Autozone use their ODBC II scanner and found that one of the Coil Packs had failed. They had a NIEHOFF WA2371 coil in stock. I replaced just the one and have not had another fail yet in over 5000 miles of driving.

I don't think I would replace them all...my motto is why replace it if it hasn't failed...except for the fluids, belts and tires, of course!

You are lucky.

I see customers do the same thing all the time and they are back within a week getting the rest replaced.

I have had customers coming in every other day getting a new one till all 5 were replaced. In the long run it cost more to do it that way. They had to pay labor each time to replace each one.