Skip the auto shop - Our mechanics make house calls

Q: Misfire but when get up to 60 to 70 miles and hour, it runs smooth

asked by on

Vehicle inspection report. Co gpm is 21p3110 should be 15.000. Check Engine Light is on. PO300 Random /Multiple Cylinder Misfire Detected.

My car has 172000 miles.
My car has a manual transmission.

A: Hi there. When I get these readings during ...

Hi there. When I get these readings during an emissions test I usually start by checking the fuel pressure. A lean running condition from a weak fuel pump will cause this. If the fuel pump is fine, then I install a scan tool and monitor the sensor readings as a bad oxygen sensor or air flow meter will also cause this. It can also occur from a failure in the catalytic converter. If you need to have this misfire and emissions problem checked, consider YourMechanic, as a certified technician can come to your home or office to diagnose why the 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・Save up to 30%

Get a quote

What others are asking

Q: 2007 Dodge Grand Caravan hard detonation problems

Take a compression tester and check the compression of each cylinder. This will determine how much pressure will hold in the cylinders. If the pressure is 120 or higher, then the cylinders are okay. If the pressure is lower than...

Q: Check light keeps blinking Isuzu Trooper V6-3.5L

The Check Engine Light under the TOD is the indicator that there is a problem in the 4WD and transmission system. Your 4WD or transmission system has diagnostic capabilities to test and get codes out. You may need to have...

Q: Engine temperature keeps going up

Hello. The cooling system is designed to keep the engine at operating temperature. Hot coolant from the engine flows through the radiator, which lowers the temperature. The lower temperature coolant is then returned to the engine. The primary cooling system...

Related articles

How Do Power Car Windows Increase Passenger Safety?
Power windows are responsible for approximately 2,000 emergency room visits every year. When a power window closes, it exerts enough force to bruise or break bones, crush fingers, or restrict an airway. Though...
How to Renew Your Car Registration in Oklahoma(DELETED)
Having your car registered with the Oklahoma Tax Commission is an important part of driving legally in this state. You will need to do this within 30 days of moving to Oklahoma...
P2103 OBD-II Trouble Code: Throttle Actuator Control Motor Circuit High
P2103 means there is a fault with the throttle actuator control motor circuit, likely due to a defective electrical component or part.