i know that it mean multiple misfires. but what causes this? is it a sensor, coils, or wires. the plugs are brand new so i dont think its that. can someone help me out with that.

 

many possible causes...you need to figure out which cyls. are missfiring and go from there.

 

he's right you need a scanner to log each cylinder

 

If you don't have a scanner that will monitor each cylinder, it may be worth paying a trusted shop for diagnosis. Throwing parts at it will get expensive. GM tech 2 will monitor each cylinder...don't know about the rest.

 

Could be a loose or bad crank pulley or a smaller than stock torque converter(if you have one). I've seen this happen. A little vibration or difference in engine balance/rotating mass will set the code. Is it at idle or does the SES light flash going down the road?

 

Usually the RMM code is a simple fix, just a bitch to hunt down. Im assuming you have a scanner since you know there is a P0300. Was there any other codes? Check your wires to make sure there is a good connection on all of them, no arcing or anything goin on. Ive had this code pop up as a result of 1 bad o2 sensor. Theres not really any sense to know which cylinders are misfiring, since its a random/multiple misfire code, its very generic. Means whatever it is its, something that affects them all.

If you had a p0303 code that would tell you cylinder number 3 had a misfire then you could look at that one specifically.

When you start the car, does it idle right briefly then start the misfire? Or does it do it form the turn of the key?

 

it will do it after a while, when its running. also somtimes it feels like it wants to shut off. but then the rpms go up and it starts working fine again for a while.

 

Exact symptoms of a bad o2 sensor. Were there any other codes?

 

just that. thats why its hard to believe that its an O2 or both. by the way i have corvette o2s.