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.

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?
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

My ecm needs replaced an I drought a used but said it needs to be programmed first an they say go to a dealer but I don't have dea

Hi there. Unfortunately, replacing an ECM is not a job that a mechanic can do unless they have access to vehicle specific software updates to program the ECU; which is very rare. The best option is to contact a dealership...

Hi I have a 2006 mercedes benz e350 how to reset the ESP light?

If there is a problem in the system, You will have to read the codes and correct the fault for the light to go out. However, If the ESP light has come on after you have replaced a battery or...

Car misfiring and is barely driving.

The modifications you have done are hard to say if they are causing the problem or not, since they are different than the original equipment specifications. The problem sounds like you are running out of fuel or you do not...

Related articles

Isuzu Certified Pre-Owned (CPO) Car Program
Drivers Drivers who have been shopping for a used Isuzu vehicle may have already considered a Certified Pre-Owned, or CPO, vehicle. CPO programs allow owners of used cars to drive with confidence, knowing that their vehicle has been inspected and...
Symptoms of a Bad or Failing Fuel Pump
Common signs include a whining noise, hard starting, engine performance issues, and an inability to start the car.
Understanding the Isuzu Oil Life Monitor System and Service Indicator Lights
Car symbols, or dashboard lights, are a car service reminder. The Isuzu Oil Life Monitor system indicates when and what service your car needs.