Hi all.
So on the way home from work, in the middle of the interstate, my car started knocking really badly and the check engine light started flashing. Funny thing is, once I took my foot off the gas pedal, the CEL stopped flashing. If I gave it a little throttle, it would start flashing again. All the while, the car was still knocking really badly, especially when I was at a full stop?

What could this be? I'm really afraid of it being something serious. Could it just be bad gasoline? Could it possibly be that my spark plugs are 5k miles overdue changing? Please help!

 

Maybe the coils are bad causing the misfire. Is it really knocking or just misfiring?

 

Hey Tech,
I'm not really smart with cars so I am kinda embarrassed to ask this but what is the difference between knocking vs misfiring? My buddy was in the car and he said it was knocking.

The best way to describe it is a slight shake, and it's almost a grumbly, audible vibration. I'm not really sure how to describe it better. Sorry man.

 

Sounds like misfiring to me. Almost like it is coughing?
You might have a bad coil or spark plug.

 

The plugs are 5k overdue to be changed.
If the coils are bad, is that costly?

 

Sorry to say but yes.
Here is a link to some on FCP groton.
http://www.fcpgroton.com/product-exe...ategory_id/111

 

Tech, you were right.
My mechanic ran the codes and it came up 0303 and 0305 misfires. The coils on cylinder 3 and 5 burned out.
Coupled with the 120,000 mile service, the two coils, and the labor, it came to $446.00 out the door, a lot more than the $150 I was hoping to get away with for the 120K.
Atleast it's running extra smooth now.

 

Glad all is running good now!!!

 

I have to bring this back to the top. Ok so two weeks ago the coils for cylinder 3 and 5 burned out. Well, driving home yesterday from work, the problems began all over again. This time, cylinder 4 coil blew.

It's just weird that the coils would all of a sudden burn out in a span of two weeks. Do coils burn out just because of age, or is it something else that could be happening (something overloading, a defect someplace else in the engine, etc.)? I don't want to risk something else happening, or the other two coils burning.
Thanks!

 

I also want to add another question. Does each cylinder have it's own coil? I read somewhere that each coil in a Volvo affects more than one cylinder. I'm not a car guy and don't know a thing about such matters. I'm just worried now that I've had 3 coils changed, something else is going to happen. I'm tired of dumping money into this car.

 

They will usually go out at the same time.
I would replace the other 2 and you should be fine from there.