Misfiring and skipping, loud noise coming from engine - especially when idling.

SOURCE: THE CHECK ENGINE LIGHT

These are classic symptoms of an O2 sensor.Go to autozone and ask them to read the engine code. They will tell you what is wrong more conclusively.

Timothy Shotwell

• 23 Answers
• Posted on Apr 21, 2009

SOURCE: 2004 Ford Taurus V6 noise underhood appears to be belt

Sounds like a bad idler pulley,or belt tensioner. Most likely not water pump since the check engine light is not on. Altho it couold be the water pump and for some reason (bad sensor, burnt out light) the check engine isnt coming on. Either way it would be best to have it looked at.

SOURCE: engine light has come on and car is misfiring,

Main causes of misfire would be loss of spark; the air/fuel mixture is too far out of balance to ignite; or loss of compression.

Loss of spark includes anything that prevents coil voltage from jumping the electrode gap at the end of the spark plug. Causes include worn, fouled or damaged spark plugs, bad wires or even a cracked distributor cap. A weak coil or excessive rotor gas inside a distributor would affect all cylinders, not just a single cylinder.

"Lean misfire" can occur when the air/fuel mixture is too lean (not enough gasoline in the mixture) to burn. This can be caused by a dirty, clogged or inoperative fuel injector; air leaks; or low fuel pressure because of a weak pump, restricted filter or leaky pressure regulator.

Loss of compression means the cylinder loses most of its air/fuel mixture before it can be ignited. The most likely causes here are a leaky (burned) exhaust valve or a blown head gasket. If two adjacent cylinders are misfiring, it's likely the head gasket between them has failed. Also, if an engine is overheating or losing coolant, it's likely the head gasket is the culprit.

You can isolate the weak cylinder by temporarily disconnecting each of the spark plug wires, one at a time, while the engine is idling. When there's no change in the idle speed, then you have pinpointed the weak cylinder.

SOURCE: Engine warning light comes on, diagnostic says

if your car give you i code thats says mutlipul misfire on number 1,2,3,or four cyl. that means that that cyl is not firing when its suppost to so if the code says number 3 cyl misfire or multipul misfire replace number 3 spark plug and coil pack and 80% of the time that will solve the problem.

Testimonial: "At least i now have an idea, i didn't get any info from the dealer about codes only workshop jargon. The car wasn't fixed and they still charged me."

SOURCE: 96 Ford Explorer is studdering (misfiring) when going up hills

I have the same exact problem that just started immediately AFTER I got a tranny service where they changed the Trans Fluid, Trans Filter, Fuel Filter. Took it back and they say nothing is wrong with it. Took it to the dealer thinking I could get some REAL answers... they just told me to replace spark plugs, wiring & coil, for $900. Only studders when quickly accelerating above 40mph. I've check other forums, they say to clean the Mass Air Flow sensor. Haven't tried it yet. This seems the easiest before replacing spark plugs. Any other suggestions anyone?? Please.....