Misfire cylinder 2

Janboer123 · Post by **Janboer123** » 01 Dec 2025, 04:41

Hello guys,
I have a volvo v70 2.4t from 1999. I drives really bad, i have no torque and only a bit of power.
It says misfire on cylinder 2. Code p0302 if i recall correctly.

I changed 5 sparkplugs and 1 coil on the 2nd cylinder but this didnt seem to help. Also i drive on autogas, but on gasoline it does the same. (Maybe worse on autogas)
The problem seems to be when im at low rpm, the car stutters and vibrates a lot. On high rpm it looks like it has power and sounds like a 5 cyl.
I was thinking about the injector that is clogged, but dont want to spend more money than is neccesary. My second guess is the alternator, because the lights and interior lights flicker when its running at idle speed. Also it had a bit of problems when i tried to start it this morning. I will do a compression test later today.

Let me know what you guys think please. I will let you know the details of my problems.

Greetings,

Post by **abscate** » 01 Dec 2025, 08:22

Check compression on number two. You can also swap the coils and plug on 2 and 3 and see if the code “ moves” to help diagnose.

I have a bad feeling number 2 has a burnt valve ftom your description.

Post by **erikv11** » 03 Dec 2025, 08:16

First check compression, I agree with Abscate. It sounds like #2 is not firing at all.

If compression is okay you can also try swapping injectors, to see if the problem moves with the injector. But be careful to not damage the o-rings if you remove injectors.

Janboer123 · Post by **Janboer123** » 04 Dec 2025, 08:39

Hello guys,

Thank you for the answers. Cylinder 2 has very low compression, about 3/4 bar. This is like 60 psi i think. I measured with a warm engine at 4 bar and also measured with a cold engine and a little oil in de cylinder, that gave 3 bar. Probably a broken valve right?
But now i have some hope, because my mechanic said it could be a stuck piston ring. It also consumes a lot of oil. I dont know how much but i think about a liter every 500 kms. Could be less, i have no idea how to measure it.
Sometimes it feels like its firing on both cylinders but this is completely random. The car drives better when i play with the throttle tho, so could this indicate that a valve is not completely closing or leaking? Or maybe the piston ring gets a little unstuck?!
Let me know what you guys think.

Post by **abscate** » 05 Dec 2025, 03:40

Probably not a valve in that cylinder. A burnt valve usually gives 0 psi/bar. Definitely try seafoam or marvel to see if you can unstick that ring.

Janboer123 · Post by **Janboer123** » 05 Dec 2025, 13:37

abscate wrote: ↑05 Dec 2025, 03:40 Probably not a valve in that cylinder. A burnt valve usually gives 0 psi/bar. Definitely try seafoam or marvel to see if you can unstick that ring.

Yes, will do! Thanks for the help, i will write some updates on this thread

Post by **Krons** » 05 Dec 2025, 20:46

An oil change interval of Valvoline Restore and Protect in addition to the MMO/Seafoam may help that stuck ring too.