I've got a '99 legacy outback with the 2.5l engine that keeps getting a check engine light withthe code for a missfire on #4 cylinder. Have replaced timing belt, coil pack, plugs, wires, injector & fuel filter with no change. compression checked good. Mechanic suggested a worn lobe on the camshaft.

Any other ideas before I sign up for new camshafts?

I would try a decarboning agent like Seafoam first. It would be pretty cheap and a lot of folks get carbon misfire.

I'll give it a try

Do a leak down test on cylinder #4. Leakdown tests are more accurate than compression tests. Check the valve clearances,-you may have a tight or slightly burned exhaust valve on cylinder #4. In addition check the egr valve and ports, you may have a sticking egr valve. Be fair warned if the valves are too tight then the damage may allready be done. It is common for the valves on cylinder #4 to get too tight then burn a valve. Good luck.

Was reading the Sea Foam site. Just pour a 1/2 pint down the PCV?

About 1/3 of a can, IIRC. Follow instructions on the can--might even search here on the board for different suggestions. Let it sit for 5 or 10 minutes then fire her up and enjoy the show!

 

Good luck.

As said above good luck! If that fails you have to go with colorblind's advice.

Tried the sea foam with no effect. Didn't think it would do much since I had the injectors cleaned. I'll start pricing a valve job.

You might try a compression check and adjustmnet a CB suggested. Sorry the Seafoam gave no joy. If a valve has just started to be too tight sometimes an adjustment can save it. If it has been running a bit open for a while I have had no luck with them. Be sure to check the EGR valve as CB suggests before tearing it down.

You might want to try the old dollar bill test on the exhaust...start the car, hold a dollor bill about 1/2 inch away from the exhaust, it should just flutter but if it alternatly gets sucked into then blown out of the exhaust there is a good chance you have a burnt exhaust valve..pretty simple but might just give you another clue to what is going on...

I had the same problem only it was the # 3 cyclinder. It turned out to be the E.C.U. Check and see if you can get a noid light to light on the # 4 if it dont light, then check to see if it has current if it does it will most likely be you need a E.C.U. also.

I've got a '99 legacy outback with the 2.5l engine that keeps getting a check engine light withthe code for a missfire on #4 cylinder. Have replaced timing belt, coil pack, plugs, wires, injector & fuel filter with no change. compression checked good. Mechanic suggested a worn lobe on the camshaft.

Any other ideas before I sign up for new camshafts?