2006 XC90 2.5L 5 Cylinder - Misfire/No Compression Topic is solved

[rakesh4404]

Hi,

I need some advise and directions on fixing this issue.

2006 Volvo XC90 2.5T FWD - 200k miles.

I recently brought XC90 with a slight front end collision and misfire.

I have fixed the following replaced radiator, radiator core support, bumper etc.

Upon move to core issues the vehicle had a bad PCV and leaked oil over ignition coil and at some point might have seeped into the cylinder. I did a complete PCV job and followed with a glove test, all fine. Replace oil filter and changed oil too.

Then proceed to changing all the spark plugs(NGK iridium) and Bosch Ignition coils. Cleaned the walls and installed.

However still had misfire so proceed with Compression test and found out Cylinder 4 had zero compression. All other cylinders hold 135+ constant except 4.

Can someone please advise steps to address this issue? I checked the following:
1. Fuel injectors
2. No coolant leak, or coolant mixing with oil due to gasket issue. Engine oil very clear.
3. Checked Cylinder 4 spark plug, coil and harness. Getting good sparks from coil.
4. Engine running strong and banging due to misfire while on idle and low speed.
5. Engine not stalling at all even due to misfire.

I am a self taught mechanic so I really appreciate some experts advise just to keep another solid Volvo on road

Thanks in advance.

[nedc]

Probably have a 'burned' exhaust valve that is missing a small chunk. Had that happen on a 960 w/ 6 cylinder that i bought w/ a misfire. Drove it on 5 cylinders for a year before I pulled the head and fixed.

[oragex]

I suggest as well posting in the 2001-2009 S60 forum mentioning the engine only, it's the same 2.5T

You may want to undo the injector #4 so it doesn't toast the catalytic converter or even the piston rings

[rakesh4404]

Probably have a 'burned' exhaust valve that is missing a small chunk. Had that happen on a 960 w/ 6 cylinder that i bought w/ a misfire. Drove it on 5 cylinders for a year before I pulled the head and fixed.

Thanks for your input, yes I am also suspecting the exhaust valve. Also fuel injector 4 had a small orange plastic piece missing at the edge. Chances are it might have stuck open on the valve.

[rakesh4404]

I suggest as well posting in the 2001-2009 S60 forum mentioning the engine only, it's the same 2.5T

You may want to undo the injector #4 so it doesn't toast the catalytic converter or even the piston rings

Thanks will undo #4 for now.

[oragex]

Probably have a 'burned' exhaust valve that is missing a small chunk. Had that happen on a 960 w/ 6 cylinder that i bought w/ a misfire. Drove it on 5 cylinders for a year before I pulled the head and fixed.

Thanks for your input, yes I am also suspecting the exhaust valve. Also fuel injector 4 had a small orange plastic piece missing at the edge. Chances are it might have stuck open on the valve.

Do you mean the orange plastic clip over the injector body ? That is not a concern but I would find it interesting that only the injector #4 is missing it, maybe this injector was already replaced for some reason ?

If you rather meant the plastic cap at the very end of the injector (where the spray comes out), those caps do fall quite often especially when the injector is pulled out from the manifold, but usually these fall inside the intake manifold and normally should not cause an issue, but we never know..

[rakesh4404]

Probably have a 'burned' exhaust valve that is missing a small chunk. Had that happen on a 960 w/ 6 cylinder that i bought w/ a misfire. Drove it on 5 cylinders for a year before I pulled the head and fixed.

Thanks for your input, yes I am also suspecting the exhaust valve. Also fuel injector 4 had a small orange plastic piece missing at the edge. Chances are it might have stuck open on the valve.

Do you mean the orange plastic clip over the injector body ? That is not a concern but I would find it interesting that only the injector #4 is missing it, maybe this injector was already replaced for some reason ?

If you rather meant the plastic cap at the very end of the injector (where the spray comes out), those caps do fall quite often especially when the injector is pulled out from the manifold, but usually these fall inside the intake manifold and normally should not cause an issue, but we never know..

I meant the very end of the injector.

[rakesh4404]

All I diagnosed that Cylinder 4 has zero compression, so I believe maybe a stuck or burnt valve.