04 Chevy Avalanche Check Engine Misfire Cylinder 2?

Asked by Sep 29, 2017 at 11:09 AM about the 2004 Chevrolet Avalanche 1500 RWD

Question type: Maintenance & Repair

After getting gas a couple weeks ago, my check engine light came on. Later,
I thought I would check out my gas cap, removed it, it looked okay, and when
I replaced it, the light went off. A couple days later it came back on again. My
girlfriend stopped to get gas a day or two later and the light went off. The
next day, it came back on again. A couple days later, I went to Autozone and
code reader. gave me a misfire in cylinder 2 code. I put more gas in it and
some fuel injections cleaner, and the light went off again. Two days later,
back on. Since this is coming on and off around me getting gas, I figure it is
maybe a pressure sensor or injection problem, but thought I would check her
to see if this has happened to anyone else and may know more specifically
what the issue is?

9 Answers


What is the code? Did you buy the right gas cap? These are very specific. Do you hear a "swoosh" sound when you take the cap off? Like it is sucking air back in.... sounds like you have multiple issues. Was this P0302 code the only one you got? Purge valve code possibly?

Yes, the P0302 code is the only one I got. I do not hear it sucking air when the gas cap is removed. It is the original cap, I have not replaced it because it appears to be good, not damage and I don't hear the sucking air sound.


I would get the same OEM gas cap to start with. You have an emissions leak since you do not hear this swoosh. How "rotted" does the rubber hoses look going into your charcoal canister? I would replace all of them and focus on the purge valve. Most of the time this is on the canister. The dealer or a shop will smoke test your system to see where/if you have emission leaks.


swap coil packs to see if it jumps to another cyl...If yes swap it out with a new one check your spark plugs too .maybe its time for a new set off AC Delcos

1 people found this helpful.

Thanks, it just passed emissions two days before all of this started. That is why this is so confusing. I will check the rubber hoses in the charcoal canister and purge valve.

B_rock, my first thought for any misfire is usually plugs and wire too, but since the light keeps coming off and on around me getting gas, I think this is more of a fuel issue than a spark issue.


It could also be faulty o2 sensor ,can you watch live data to see if o2 are dropping or spiking otta range perf.

No, I can't watch live data, don't have the proper equipment. But I don't get the P0140 Oxygen sensor code, I am only getting the P0302 code for the cylinder misfire. I am going to start with a new gas cap and check the rubber hoses on the charcoal canister and purge valve and let you know how it goes.

You need a scantool to properly diagnose. You can buy a dongle for about $10 on Amazon and a $5 app. You can also build yourself a smoke machine to find the leak. They are nearly impossible to find without the smoke a lot of the time.

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