I got this code from my car, P0300 Multiple Cylinder Misfire Detected,
what do I have too do to repair my car? does anyone know?

 

Start cheap and work your way up. Replace your plug wires first. If they are old and dry rotting they could be arcing to each other or the engine. If that doesn't do it go to the plugs, then the coils. Also check for any lose connections on anything.

 

I did a complete Tune-up on my car,
Spark Plugs and Spark Wires, I changed 5 injectors from the 5 cylinders
that were misfiring, I have put over 200 miles in my car
and the code P0300 did not come back.

 

Okay I have a cylinder 6 misfire. I have changed the coil pack for #6 and I but all new ac delco plugs in and changed the wires and hasn't helped. I took it back to the mechanic and he looked in over and can't find anything wrong. It seems to only mess up after in warms up but doesn't do it all the time so it making it very hard to find the problem. any ideas? I thought the injectors but the mechainic checked all that and said they were fine.

 

Okay I have a cylinder 6 misfire. I have changed the coil pack for #6 and I but all new ac delco plugs in and changed the wires and hasn't helped. I took it back to the mechanic and he looked in over and can't find anything wrong. It seems to only mess up after in warms up but doesn't do it all the time so it making it very hard to find the problem. any ideas? I thought the injectors but the mechainic checked all that and said they were fine.

 

Welcome to the forum. P0306? On what model, year, and engine? Freeze frame data available?

 

6 cylinder, 99 chevy, malibu

 

Has your mechanic done proper fuel injector tests? How about cylinder compression and leak-down? Either he is not a good diagnostician or he doesn't have the time (if it takes half a day, are you willing to pay for the time spent?). Ask him what it'd take?

 

EinST could not have put it any better. I was thinking same thing as I was reading.
How did your mechanic check the the injector to determine they are all "fine".
Once a problem goes further than a simple ignition misfire the testing gets more complex and involed which cost more money. What kind of equipment does the guy have to do the testing?

 

Yeah he tested my injectors, compression, ect. He has 30 years experience. but since i got it back its only missing occasionally and not enough to trigger my check engine light. so just wonder maybe bad gas is a factor?