QuestionHelp!Diagnostic:p0300-random misfire,p0301-misfire cylinder 1,p0303-misfire cylinder 3,p0305- misfire cylinder 5,p0141-downstream heater failure,valve cover casket leaking. I had casket replaced.Once the car heats up,when idling she skips and wants to turn off.This has occur since she stalled on Mother's Day. While driving she stopped running.I have been to 3 mechanics.They are not listening to me.She turns on and runs great for about a mile then she wants to turn off.
AnswerHi Irma,
It is interesting that the 3 cylinders that are drawing a specific code (1,3,5) are all on the same cylinder bank (the one closer to the firewall. It suggests that we focus on those specifically and perhaps not pay too much attention to those factors that affect all the cylinders equally (system-wide issues). However there is one thing that is easy to check and could be the causing the poor idle condition when it warms up...the exhaust gas recirculation valve (egr valve). 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 you should be able to now start the engine. You can, once it is idling, check that the valve stem moves when you rev the engine from idle to 2500 rpm and back to idle. See if that corrects the problem.
The first thing that is specific to those cylinders is that it is difficult to replace the spark plugs because they are at the rear of engine compartment. How many miles ago were those spark plugs changed? Could someone have just changed the 2,4,6 plugs and not done these? The plugs are supposed to be changed every 100,000 miles.
It is also the case that to change the plugs you have to remove the upper manifold. It is possible that the bolts on the rear side of the manifold are a bit loose which will allow air to leak into the manifold and that would be a cause of the cylinder to misfire. To check that, when the engine is running poorly, try spraying very short bursts of starter fluid (caution very flammable, only short bursts) with a straw applicator at adjacent spots around the edge of the manifold. If there is a leak, immediately following a burst of fluid you will notice the engine momentarily speed up and stop missing. If it does, then that is the next step...check that the 7 manifolds bolts are tightened to the correct torque: 13 foot-pounds. If that doesn't fix it, then the intake manifold gasket would have to be replaced. That is different from the valve cover gasket which I understand was replaced. But if the test with starter fluid shows a leak then that has to be fixed to have a chance at solving the multiple misfiring.
Those are the things I would try first.
Roland
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