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

asked by on October 25, 2016

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.

Fuel Pump Replacement $120.92 - $1186.72 Get a Quote
Oxygen Sensor Replacement $108.80 - $869.59 Get a Quote
Catalytic Converter Replacement $279.51 - $3103.51 Get a Quote
Engine is misfiring Inspection $79.99 - $89.99 Get a Quote

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.

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