A PO300 is a random misfire. Many things can cause it. Start easy.. check for vacuum leaks, and check fuel pump pressure to make sure it is within spec.

Answered by Jacobandnickolas (expert)
57,318 answers provided

if you have the engine scoped they will tell what cylinder is causing the misfire.it may be a bad plug or wire.

Answered by cadieman (expert)
2,852 answers provided

http://www.2carpros.com/articles/engine-misfires-or-runs-rough

1.Defective spark plugs

2.Inadequate spark/coil,defective spark plug wire.

3.Lack of compression

4.False air leakage.

5.Faulty fuel injectors.

6.Insufficient fuel pressure.

7.Contaminated fuel.

8.EGR valve that is leaking.

9.Oxygen sensors.

10.Throttle position sensor.

11.Manifold absolute pressure sensor

12.Mass Airflow Sensor

13.Idle air control valve

Note: If it doesn't apply disregard it-

Answered by rasmataz
68 questions asked