This is located to the left and behind the throttle body, under the intake manifold for the Duratec.įor the vulcan, PCV snaps/screws/presses (depending on year) into the valve cover nearest the firewall and the 90 degree elbow runs up and connects to the upper intake manifold. These elbows become oil soaked and collapse, creating a leak. The most common leak is on 00-03 duratec and 01-03 vulcan motors where the PCV hose connects to the intake manifold with the PCV elbow. It is time to check if you have a vacuum leak. Gap should be between 0.042 and 0.046 inches.Ĭheck for correct routing of the plug wires, sometimes they may be put back incorrectly after changing the spark plugs.Ī vacuum leak can cause a rough idle, misfire, and poor fuel economy. Replace your spark plugs with OEM motorcraft (Part # AGSF-32FM), or Autolite double platinum plugs. In that case you need to change the valve cover gaskets and the O-rings surrounding the spark plug wells. On DOHC engines, oil on the outside of the plug can also contribute to misfires. If you are out of ideas and have not replaced the plug wires, do so. Sometimes bad wires cannot be discovered without cutting them open.
If you see arcing, you need to change both the plug and the boot. You should also check your spark plugs for signs of arcing or carbon tracking on the porcelain when you take them out. At least inspect the wires for worn insulation and the plug boots for any cracking. Replacing plug wires is also a good idea at this time. The first step would be to replace your spark plugs if they are old and have over 100k miles on them, they are going to need to be replaced anyways. Sometimes as plugs get older, they begin to fail at the same time.Ī poor firing spark plug or one that has a poor spark will casue a misfire. Older spark plugs do not always fire correctly. Keep in mind purchasing low quality parts will sometimes hurt your problem rather than help it.ĥ) Camshaft synchronizer shaft ( OHV only)Īdvanced User Misfire Diagnosis (good for those who don't have a CEL on but feel a misfire). Part changing is an irrational way to attempt to fix the problem.
Bad cylinders won’t change the idle when unplugged.īy reading your codes, you can help diagnose which cylinder seems to be the problem. Unplug the plug wires from the coil one by one.
If it misfires and doesn’t throw a code, you can do a power balance test to see which cylinder is misfiring. Sometimes the PCM will not pickup on a misfire if it is partial or the monitor is not working correctly and the CEL may not light up even though you feel a misfire. You can read Check Engine Light ( CEL) also known as the MIL (Malfunction Indicator Light) through the OBD-II port under the driver’s side dashboard using a scan tool like TOAD. If your CEL is on, read the codes and figure out what cylinder is the problem, or if it is a random miss. Failing to do so may damage expensive catalytic converters and/or cause permanent engine damage.įirst step to diagnosing a misfire is finding out what cylinders are misfiring, and when it occurs (under load, idle, when you let off the gas, etc). If flashing and misfire does not stop when lowering engine load, pull over immediately. WARNING: Do not drive agressivley if flashing CEL and misfire occurs, let off gas immediately. If any one of those is absent, mistimed, or sub-optimal, the cylinder will misfire.
MISFIRE MONITOR PROFILE CORRECTION SCT X4 DRIVER
Misfires may or may not be felt by the driver depending on the severity.Ī cylinder needs the proper amount of air to fuel mixture, spark, and compression to fire. Unless the light is flashing, the misfire may not be presently occurring because the problem is stored in memory for some time after the event. If the misfire is severe enough, it may generate a flashing CEL or MIL to warn of a severely damaging misfire, or the light may come on solid if a less severe misfire is detected (which should still be fixed ASAP). This article covers both misfires basics and misfires advanced content (for expert DIY'ers or mechanics).Ī misfire is when one or more cylinders do not fire at all, at the correct time, or incomplete combustion occurs.
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