The other day on my way to work then car suddenly lost a little power, ran rough and engine light started flashing. Once at work I hooked the scanner up and got a code for the rear o2 and multiple misfire. I pulled each plug wire while it was running and there didn't seem to be any change in the way it idled.

Installed new o2 sensor and that code is gone now. Got a different coil and wires and now I have misfire cylinder 3. I swapped 3/4 wires and plugs. Swapped cylinder 3/4 fuel injectors also. Everything I do, it keeps Comming up cylinder 3. I'm going to go grab the cheapest plugs I can just to test it. I'm worried it's something allot more serious.

 

And my cylinder 3 spark plug tube seal leaks oil. Could the cylinder have oil and it's not getting?

 

Turning over with no plug in cylinder 3 produces oil splatter.

 

#3 plug. Doesn't look like it's firing at all. Covered in oil

 

 

I don't know why I couldn't get the compression test gauge to work. Every cylinder besides #3 made the needle jump up and down. I just pulled the valve cover, no broken springs. I'm at a loss here. I'm sure the head needs to come off next right?

 

My cylinder 3 has no compression. Removed valve cover and I don't see any damage. What's next? Removing the head to see the valves and Pistons? If it's the Piston itself, am I able to change only that one without any problems?

 

As long as you are doing the compression test correctly, it sounds to me like a badly burned valve in #3 cylinder.
I'm not sure about the oil splatter; the plug looks about OK to me.
What compression readings did you get?
Mike

 

Couldn't get a reading. Needle was just bouncing except cylinder 3.

 

Is the release button on the tester stuck open? All 4 plugs out? Throttle wide open?
Try a different compression tester?
You should see the needle pump up, after about 4 or 5 cranks, to about 160lbs+/-.

 

I didn't have throttle open...

I put my finger In Each tube while cranking and 1,2,4 pushed and sucked my finger really strong. #3 barely at all

 

Well, that's certainly one way of doing it!
I'd still hope it's just a burned valve. Expensive, but better than a holy piston.
Time to get the head off, I think, & see what's in there. Fingers crossed.

 

Thank you. That's what I'll start working on then.

I'm used to the old small block 350 lol. NNo this stuff.

 

More likely a burned valve!
Do you have good compression in the other three?

 

Will I know right away once head removed?

 

Usually, if it is a burned valve, you'll see a small chunk missing from the valve head.
If you truly have NO compression at all in that cylinder, it will be large chunk missing.
Check the top of the piston for damage - the broken chunk may have scratched/scored/dented it. If it's not too deep it's not a big deal in my opinion.
Worst case there's a hole in the piston - that's a big deal.

 

Usually, if it is a burned valve, you'll see a small chunk missing from the valve head.
If you truly have NO compression at all in that cylinder, it will be large chunk missing.
Check the top of the piston for damage - the broken chunk may have scratched/scored/dented it. If it's not too deep it's not a big deal in my opinion.
Worst case there's a hole in the piston - that's a big deal.

Can you stick to one thread, please? !

 

I'm in the process of removing the head. Man it's allot of work.

Found this. Maybe that's my loss of boost?

 

Found the problem.... Both cylinder 3 exhaust valves burnt.

 

Please understand this: The result you found, is not the problem. The valves most likely burned, due to a lean running engine, which may have been and injector, the use of regular (lower octane fuel, leaks in the intake system, valve lash too tight (really only thing here is loose valve guides. Make sure to replace them and check the other guides and valves for wear also), or possibly mis tuned. This cylinder got really hot to burn the valves this badly!

 

If you look at my post above you'll see a crack in the intake pipe.

Also, the injectors don't look the best. I've only ever ran premium fuel but I've only owned it for a couple months. So I'm not sure what previous owner ran in it.

 

is it tuned?

 

Not that I'm aware of. It's completely stock.

 

Based on the one photo you posted, it looks like the left hand exhaust valve in Cylinder 4 is also starting to burn, based on the discoloration around the rim of it. I had to swap a cylinder head on my R50 because it had low compression in 2 and slightly low compression in 3.

I'm including a photo of my cylinder head for comparison.

My R50 cylinder head with burned valves in cylinder 2 and 3.