Q: high idle when hot and missfire all the time.

asked by on

so I replaced a blown head gasget and now I know I timed it correctly but I put it back together and now I am getting check engine code p0300,p0301,p0303 I see white smoke out of the muffler and it smells of burnt oil and idles at 2000rpms and has a missing fire sound. when cold not as often misfire sound and 800rpm idle. I checked the pcv valve and it is fine. its not getting hot. idk what to do? thanks.

My car has 207000 miles.
My car has an automatic transmission.

If you overheated the engine prior to replacing the head gasket you would need to have the head checked for cracks and get the surface refaced. If this has been done, then the problem may be that the cylinder block is cracked, or you have not put something together properly and have a vacuum leak. The left over coolant in the exhaust from the previous overheating may be the reason for the smoke which will eventually go away.

Check the cooling system and engine for overheating again, if so, then you will need to find where the coolant is getting into the cylinders. A certified mechanic would be able to diagnose the symptoms you’ve described to in order to fix your misfire and high idle issues.

Was this answer helpful?
The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details
  1. Home
  2. Questions
  3. high idle when hot and missfire all the time.

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: Is there any good reason to spend extra money on premium gasoline?

Premium fuel should only be used if the manufacturer recommends it. You will see it printed on the fuel gauge if you are required to use it. All fuels sold in the USA have cleaners in the fuel now. Some...

Q: Leaking coolant and white smoke from radiator cap

Hi there. A blown head gasket is typically the result of an overheating situation, not the cause. So, if your engine has been overheating recently, it's possible that engine damage has occurred. However, it is more likely that the radiator...

Q: My car cooling fan works for a few seconds when I turn the car off, not on when the car's on. Is the temperature sensor bad?

If it doesn't run for more than about a minute, that could be a normal situation. The fan is triggered by temperature at the cylinder head, and when the engine is off and the coolant isn't circulating, the heat rises...

Related articles

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...
P0240 OBD-II Trouble Code: Turbocharger Boost Sensor B Circuit Range/Performance
P0240 code definition Turbocharger Boost Sensor B Circuit Range/Performance What the P0240 code means P0240 is an OBD-II generic code triggered when the Engine Control Module (ECM) detects the intake boost...
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.