aps45819 Posted January 27, 2006 Share Posted January 27, 2006 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? Quote Link to comment Share on other sites More sharing options...
cookie Posted January 27, 2006 Share Posted January 27, 2006 I would try a decarboning agent like Seafoam first. It would be pretty cheap and a lot of folks get carbon misfire. Quote Link to comment Share on other sites More sharing options...
aps45819 Posted January 27, 2006 Author Share Posted January 27, 2006 I'll give it a try Quote Link to comment Share on other sites More sharing options...
color-blind Posted January 27, 2006 Share Posted January 27, 2006 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. Quote Link to comment Share on other sites More sharing options...
aps45819 Posted January 27, 2006 Author Share Posted January 27, 2006 Was reading the Sea Foam site. Just pour a 1/2 pint down the PCV? Quote Link to comment Share on other sites More sharing options...
Olnick Posted January 27, 2006 Share Posted January 27, 2006 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. Quote Link to comment Share on other sites More sharing options...
cookie Posted January 27, 2006 Share Posted January 27, 2006 As said above good luck! If that fails you have to go with colorblind's advice. Quote Link to comment Share on other sites More sharing options...
aps45819 Posted January 27, 2006 Author Share Posted January 27, 2006 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. Quote Link to comment Share on other sites More sharing options...
cookie Posted January 27, 2006 Share Posted January 27, 2006 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. Quote Link to comment Share on other sites More sharing options...
Downbound Posted January 27, 2006 Share Posted January 27, 2006 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... Quote Link to comment Share on other sites More sharing options...
tcspeer Posted January 27, 2006 Share Posted January 27, 2006 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? Quote Link to comment Share on other sites More sharing options...
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