Fuel pump could be going bad check fuel pressure that will make it sputter,if that not the case check fuel filter.
do a compression test on cylnders
have you replace fuel filter , 1 bottle sea foam.
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SOURCE: cylinder 3 misfire
Make sure you're using the recommended spark plugs. When my car did that, I had put Bosch Platinum Plus-4 plugs in and got that same problem. Turns out the plugs are too hot and cause it to fire prematurely and kick the misfire code.
SOURCE: 2004 pontiac grand am misfire
Check the plug wires for those 2 cylinders, next check the injectors, as they can cause misfire when defective.
SOURCE: what causes a misfire on a 99 pontiac grand am if
How do you know the spark plugs are good??
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: need spark plug wiring diagram
This should be the firing order diagram for that vehicle and let me know if you need any help to understand this diagram, or if you require any further assistance.
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It doesn't do it all the time either. It only happens once maybe every 5 to 10 minutes. I rechecked the timing and took it for a drive and got it up to 70 without a single sputter but then on the way back it did it a little bit. I'm going to try the fuel injector and see if that will work. On the spark plugs I didn't buy anything top of the line. I just got your standard plugs for the model car. If the fuel injector doesn't work I will try the other solutions. What in your opinion is the best fuel injector and how many bottles should I use?
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