QuestionQUESTION: Hi Roland,
Mine is 97 Sebring JXI 6 cylinder.
Yesterday, while I was driving the "Service Engine Soon" light came on. Went to the mechanic and had the codes checked this mornin. It came up with misfiring in 5 cylinders. Asked on what I should, I was recommended to do a engine tune up. Also the valve cover gasket is leaking. But the engine seems to be running normally as before. Should I go in for the tune up? If so is that something that I can do by myself?
Thanks!!
ANSWER: Hi Omai,
A 'tune up' is a term that is no longer relevant and likely will not solve the issue but cause unnecessary expense. If you indeed have 5 of the 6 cylinders showing some misfiring, then I would point out that the repair manual lists about 18 different possible reasons. A tune-up only implies the spark plugs, so I wouldn't start with those. The trick will be for a mechanic to prioritize those and check the ones with the highest likelihood and least cost. That is not a 'tune-up' but rather a 'diagnosis'. That would involve thinking about what items can cause a general 'miss' such as an incorrect fuel/air mixture ratio.
Let me give you some ideas to try yourself:
The first thing I would do is check the mechanical function of the egr valve which is located along a pipe that runs from the left exhaust manifold (on the side of the engine facing the front of the car) to the intake manifold area (where the incoming air in the large rubber tube enters the throttle). That valve is metal and has a round fitting with a vacuum hose attached, mounted on the top of the valve, and the round part is attached to the main body of the valve by a sort of saddle. Inside the open saddle you will see a metal rod (with a slot) that connects the round top fitting to to the valve body. That rod is a stem on the valve and it is supposed to go in and out in response to the engine vacuum which varies with RPM and throttle opening (gas pedal position). Take a spray can of WD-40 or other penetrating lubricant and spray the stem where it enters the valve body and then use a regular screwdriver blade tip inserted in the slot to lever the valve in and out to try and free up its motion. Also check all the rubber vacuum hoses associated with the valve and a nearby vacuum solenoid valve. If the valve seems to open (against the action of a spring) and close firmly by the spring action when using the screwdriver blade to facilitate the motion, then that would be normal situation.
Another maintenance item would be to remove the air cleaner to expose the throttle body where the valve that the gas pedal controls is located. Open the valve by hand (press on the throttle lever which is normally operated by the gas pedal, have a helper operate the pedal to see where it is) and then use a small rag/q-tips to clean the throat of the valve body and the back side of the metal plate that constitutes the valve. Use a solvent to help clean it out, also notice an air passage way on the side of the thoat and use some solvent and a q-tip to clean that out.
The only 'tune-up' item you might consider would be to replace the spark plugs, but that only needs to be done every 100,000 miles. So look at you previous repair records to see at what mileage that was done and only consider it if you are approaching 100,000. It is a challenging task to get at the 3 plugs on the rear side of the engine so I wouldn't recommend that for an amateur.
The other thing is to periodically in the near future get a code readou, for free at an Autozone parts store, and watch for a new code that would be more specific as to cause than the 'multiple misfire' code that you have now.
Roland
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---------- FOLLOW-UP ----------
QUESTION: Roland, thanks much for those suggestions. I am at work and will try it when I get back home. The mechanic told that the leaking oil was getting into the spark plug and hence the misfiring. Is that a possibility? I also had a distributor rotor change about two weeks back. When that was changed the TPS gave way and had that done at the same time. I am not sure if those were relevant to this but just wanted to get you the complete picture...
Thanks again for your time!
AnswerYou could also try simply tighting down the valve cover screws a bit to see if that slows or stops the leaks, and if not change the gaskets. Oil around the plugs could cause misfiring, so see if you can do something to reduce or eliminate that source of misfiring.
You are welcome.
