Big Trouble 2: The plot thickens

Discussion in 'Generation 4 - Maintenance & Troubleshooting' started by Zpak, Jan 18, 2021.

  1. Zpak

    Zpak Es Aich Oh!

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    So I changed the fuel pump relay after low fuel pressure and multiple misfire codes and all seemed well. Started It before work last night and noticed a slightly rough idle at start but the drive was fine. It snowed on me at work overnight so remote started it for a good 10-12 minutes before I walked out to brush it off. When I got in the engine light was on again. I pulled three new codes. P0302, Po316, P219A.

    Cylinder 2 misfire
    Misfire on start in first 1000 revolutions
    Bank 1 air fuel ratio imbalance

    I drove home and watched AFR, fuel trims, misfires, and knock like a hawk. No misfires registered, though I did notice some popping. AFR was normal, .97-1.3 LTFT was up slightly but only 1.22 from my normal 1.15 and short term was normal.

    I find it hard to believe that the two events aren’t related but the fuel relay was definitely bad because I was dead in the water before I changed it. Now I’m back to thinking injector but I definitely don’t want to dive into that on a hunch. I’ll swap the coil pack today and look at the plug to see if anything changes but I don’t think that would account for the AFR code.

    Ideas?
     
  2. yaycandy

    yaycandy The Slack Jawed Yokel

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    I had similar issues chasing an issue. Didnt realize the cylinder was dead. Not saying thats your issue. Check compression, quick and easy to do. Make sure cylinder and valves are good first. Then continue in to spark and fuel
     
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  3. Johnbigdog

    Johnbigdog SHO Member

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    The bank 1 air fuel ratio code just means that the car is seeing a difference in the air fuel ratio between cylinders on bank one.

    A misfire will cause the 02 to see a different fuel ratio between cylinder number 2 and 1/3. So once the misfire is fixed they will all be fixed.
     
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  4. Zpak

    Zpak Es Aich Oh!

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    Thank you for that info John. I started simple and swapped the cylinder 2 coil with 6. Checked the plug in 2 and it looked good. I was relieved it wasn’t soaked in gas. It seemed to still have a slight miss but after a drive to work and three or four starts still no codes. We’ll see after I drive home this morning. I’m thinking if it is that injector it’s plugged up not stuck open. Not sure one is worse than the other but...
     
  5. Zpak

    Zpak Es Aich Oh!

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    CEL did come back on the way home, except this time P0300-multiple cylinder misfires. Along with the same P0316 and P219A.
     
  6. FiveLeeter918

    FiveLeeter918 Ortiz Performance Sales Sponsoring Vendor

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    Looks like your due diligence has met all of the things I was going to recommend. Swapping plugs, checking for gas soaked plugs, how is your fuel rail pressure? how is LPFP pressure?

    Are you able to post a log? Not sure if you've already discussed this with Brad, but the heightened fuel trims hint at a potential leak, and if it's on the engine side it can definitely give you a run for your money on diagnosis. How is your wastegate duty cycle? Does the issue tend to present it self cruising only or when spirited driving?
     
  7. Zpak

    Zpak Es Aich Oh!

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    Thanks for the response Lee.

    The miss is there and noticeable throughout operation, idle, cruising, romping. Fuel pressure is normal. I have been thinking about intake air leak, but would you consider LTFT going from 1.15 to 1.22 a measurable enough rise to account for unmetered air causing issues?

    Haven't looked at WGDC. I honestly never pay attention to it to know if it’s abnormal.

    Is there any possibility a bad O2 would cause a misfire?

    What about crank or cam position sensor?
     

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