P0440 code showing for a 03 gmc envoy

Question

We have a 2003 gmc envoy. We started having issues with certain speeds the rpm's will go up or it is missing. We changed the spark plugs and it's still doing it. Now when we are going 55 down the road it's chugging. Any idea what it could be so I'm not changing a bunch of different parts. Or is there somewhere we can take it to pinpoint the problem?

Answer 1

P0440 Evaporative emission control system malfunction

Is this the only code showing? A EVAP code P0440 is usually set due to the FTP (Fuel tank pressure) sensor not reporting the correct tank pressure , But there is a possibility it is related to the drivability that you have , and that would be the purge solenoid that sticks open at times then yes you would have stumble as you accelerate due to the engine fuel ratio going lean, You may have to resolve this code , the reason at this particular year the ECM can suspend any other code that is setting as long as it is not catalytic damaging,