DA1984VETTE

I was driving yesterday car started running really bad and rough idle when at stop. I checked the codes and got the P0300 which I knew from checking is a misfire. I unhooked each fuel injector individually and the only one that seemed to have any effect on the engine while running was the first one on drivers side which would be #1 cylinder. The others seemed to have no effect. Would I be right in saying that this injector would be the cause of my problems? Any input would be appreciated..I did post in tech..

not2old

I don't think I'm understanding something. Eliminating spark or fuel to a cylinder will change the idle if that cylinder was functioning properly. When you find a cylinder that makes no difference, you found the bad wire, plug, coil, injector, etc. If none made a difference except for number 1, it would seem the motor is running on 1 cylinder. I don't think that's the case!

Did you just fill up ?

73Corvette

It would appear that is the cylinder that is throwing the P0300 code, but it might not be injector? Could be a number of things...
As mentioned above it might be bad gas...
I'd try a can of Seafoam and see if it helps...


P0300 is random/multiple misfire.

You may want to try a good OBDII code scanner to get the freeze frame data (conditions when it sets the code)

Random misfires that jump around from one cylinder to another (P030x codes) also will set a P0300 code. The underlying cause is often a lean fuel condition, which may be due to a vacuum leak in the intake manifold or unmetered air getting past the airflow sensor, or an EGR valve that is stuck open.

Other things to check...
coil packs
injectors
vacuum leak/s

Even more things to check...
oxygen sensor/s
cat/s
valves
pcm