Skip the auto shop - Our mechanics make house calls

Q: Random misfires

asked by on

About a month ago, I started getting misfires at random times. Since then, it has gotten worse. When the car starts up like normal, every three seconds, it will misfire, and the catalytic converter gets hot - hot enough to turn red. The code reader just gives me "P0300" - random misfire. I have checked the coils, and they were fine. We switched them out anyway, and that didn't help. We tried using three ignition control modules, but there was no change. A new ignition coil went in yesterday, because the old one had a slight burn mark and was arcing. When I changed it, the car ran fine for a second, then went back to misfiring. There is a lot of clear condensation coming from the exhaust, but I don't think it is anything bad like coolant or oil. What could be causing these misfires?

A: Hello. There are several possibilities that...

Hello. There are several possibilities that could explain why you are having this problem.

  • One possibility is that you could have one or more faulty fuel injectors, or the fuel injector wiring is damaged.

  • Another possibility is that one or more spark plugs have fouled out.

  • It is also possible that there are bad internal engine parts.

I would suggest that you have a certified technician, like one from YourMechanic, come out and diagnose your car to find out why your engine is misfiring.

Was this answer helpful?

Need advice from certified mechanic? Get help now!

Over 1000 mechanics are ready to answer your question.
The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details

Get an instant quote for your car

Our certified mechanics come to you ・Backed by 12-month, 12,000-mile guarantee・Fair and transparent pricing

Get a quote

What others are asking

Q: Battery replacement.

Hi There, It sounds like you may have a battery that may be capable of holding 12 volts, but not maintaining the proper voltage under a load (i.e. starting). When you turn the key, the draw on the battery is...

Q: Car not getting enough fuel

P0300 is an engine code for multiple misfires. These are possible causes, vacuum leaks, damaged hoses or improper routing, fuel contamination, ignition system (ignition module, coil, spark plugs and wires,) or a fuel system issue. If there are specific codes...

Q: I have a check engine light coming on and off. Scanned code is p0013. CMP solenoid fault. 2008 Pontiac G6

Hello - the P0013 (camshaft position actuator solenoid control circuit) code you have could be caused by several issues. This could be an electrical issue with the wiring to that solenoid itself. There may also be a problem with a...

Related articles

How Long Does a Heater Control Valve Last?
Keeping the right amount of coolant in a car is essential in keeping the engine at the right temperature. Failing to have the right amount of coolant or even bad elements...
P0052 OBD-II Trouble Code: HO2S Heater Control Circuit High (Bank 2 Sensor 1)
P0052 code definition HO2S Heater Control Circuit High (Bank 2 Sensor 1) What the P0052 code means This code is seen when the Engine Control Module (ECM) tries to control the...
How Much Does a Mechanic Make in Vermont?
Automotive technician jobs in Vermont have an average mechanic salary of $37k, with some mechanics earning a salary of $53k.