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Cylinder 2 misfire

2008 ford explorer 4.0 V6 cylinder 2 misfire under heavy acceleration usually occurring around 3500 to 4500 RPM’s. When this happens the CEL will begin to flash and the engine will miss for maybe a minute then the CEL will go off or just be solid and the engine quits missing and the car will drive like normal.Very rarely but it has happened it will sputter when talking off from a complete stop it just seems to bog down or have no power for a few seconds and then it picks up like a switch came on . It does not matter what the temp is outside or the temp of the engine. And pretty often it takes a few more seconds to start than it used to or usually does. Spark plugs and wires were changed about 2 years ago and have about 25,000 miles on them (and more recently just for giggles I changed the cylinder 2 plug to no avail) the ignition coil (its a coil tower) was changed about 6 or 7 months ago and the fuel injector was changed about 3 or 4 months ago. Unfortunately the shop cannot not find a definite fix they suggested changing the plugs and a complete fuel system cleaning (which was done about 20,000 miles ago). Any ideas or suggestions would be greatly appreciated.

The shop should have found stored codes. Do you know what they were? They should be written on your copy of the shop order.

There are a host of possible reasons for a cylinder misfire. They include an ignition system problem, a fuel delivery problem, a compression problem on that cylinder, and a crank position sensor problem. A compression problem on a single cylinder can be caused by a valve problem, a breeched headgasket, or even a stuck or broken piston ring. Good compression is important for good ignition. Codes would be a good place to begin the search. An engine analyzer would be a fantastic tool to use, but it sounds
like your shop didn’t do so… or did they?

the only code is p0302

Has anybody hooked up a compression gauge and a vacuum gauge yet?

not this time but the last time they did and they said it was normal

that was compression not sure about vacuum gauge though

With good compression and your service history, the suspect is a sensor. It is a safe bet that whatever codes are getting stored, they do not point directly to the problem. If the code pointed directly to the problem, the shop would have fixed it already. The codes will hopefully provide a clue and point in the general direction of the problem.

The computer will set a code if it gets a reading that is out of bounds or if it gets a reading that does not agree with other readings. For example, if the throttle position sensor, RPM, and mass air flow reading do not “fit” with each other, the computer will generally set a code for mass airflow sensor, when the real problem might be a hole in the air inlet tube or obstructed exhaust.

You can get an OBD reader fairly inexpensively. It will help if we know the codes being set and the order in which they are set.

the only code being set is p0302 (#2 misfire)