Failing Spark Plug Coils! HELP
 

I have a mystery on my hands, hopefully someone can give me an answer.

My '99 S80 T-6 started idling and running real rough. I got an associated emission control msg. and a flashing check engine light. I pulled a coil off each spark plug one at a time and found one not producing a spark. I went to Volvo parts and bought a new one($60.00) , installed it and the car rode great for ten minutes. Then the same problem occurred with the rough idling etc.. I removed all the turbo tubing again and found that another coil went bad. Back to Volvo to get number two coil. I installed that one but this time but I still had the rough engine. Day number two, I am refreshed and thinking clearly. I find that two other coils are bad. My question is why did all the coils work properly after I replaced the first bad one, for about ten minutes. I already moved the last two bad coils around to see if it was not the wiring. If I buy two more coils, will they keep on shorting out for some unknown reason. I feel I am so close, I would hate to bring it to the dealer, after all the work I have done. Why all of a sudden are these coils going bad? The car has 115K on it.

Thanks and the pressure is on since my wife needs the car!













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RE: Failing Spark Plug Coils! HELP
 

The coil packs are Known weak spots when the car has miles on it.
I would replace all of them at the same time.

Maybe even the Plugs while you are at it.

RE: Failing Spark Plug Coils! HELP
 

Thanks for the quick reply. I replaced the plugs with the first coil replacement. I used Autolite double platinum, plug #APP3923. Since I have been trouble shooting car and it took awhile to figure out that I needed to stuff the turbo ducting with rags to create a backpressure, while I checked each coil(otherwise the car would snort and die). Did I ruin these new plugs since the car has been running like a diesel. Also are these Autolites any good or shoud I spend another $45.00 for Volvo plugs? Why do you think the other coils failed within that 10 minute period. The car ran great for that short time, could there be something causing them to fail? Thanks Again!!!

RE: Failing Spark Plug Coils! HELP
 

I would buy Bosch Platinum plugs. Volvo's are picky about plugs to.

I think that since you have the New good coils on some and not the others then that started to fail.
They were weak to begin with and with the new ones they need to work harder to keep up.

RE: Failing Spark Plug Coils! HELP
 

Thanks, I will buy another 4 coils tomorrow. You would hate to throw away these 6 new Autolites, but if Bosch will make a difference....

You would get rid of these new Autolites?

RE: Failing Spark Plug Coils! HELP
 

Can you explain why the older coils are working harder because of the two new coils? Don't they work independent of each other?

RE: Failing Spark Plug Coils! HELP
 

The new ones are smooth flowing. The old ones are cracked and harder to get the spark out of.
It sounds funny but been down that road before.

I would get the Bosch plugs to be safe.

RE: Failing Spark Plug Coils! HELP
 

Thanks for the advice. I replaced all of the coils and bought the OEM spark plugs. The car runs great! I did get a little nervous when I drove the car around the block. It was running great, but when I put the car in neutral, I had no throttle response at all. The same in park, no response(idle is all I could get). I took it for another drive and this time something reset and all is normal. Could you explain this one?

RE: Failing Spark Plug Coils! HELP
 

Computer or throttle body Brain fart maybe.

Were the codes still stord in the computer?

Was your foot on the brake?

RE: Failing Spark Plug Coils! HELP
 

My foot was not on the brake. I'm thinking the computer just needed to "reboot". Anyway, I am getting my free ETM software upgrade on Friday. Again, thanks for you help!!!
Dave

RE: Failing Spark Plug Coils! HELP
 

No problem Gald I could help.

RE: Failing Spark Plug Coils! HELP
 

well i think im having the same problem i changed the plugs and a little better but i will have to buy six coils to make it run right and another question do i have to have the computer reset after i do this

RE: Failing Spark Plug Coils! HELP
 

never hurts to check out all the coils whenever you do a spark plug change or if just checking one coil. Also coils tend to have lived their life at 100k.