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Having problem with cng e250

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  • Having problem with cng e250

    Hoping someone can help me with this problem I've been having. I purchased a 2010 BAF converted e250 a few months back. When I got it, it was giving me lean error codes primarily on one bank and sometimes on both banks but I would only get the error codes if the tanks where 1/4 or greater full. The check engine light would come on right after filling the tanks when I would start the van and then become less frequent as the pressure in the tanks dropped. 3/4 of the codes I got came right as I started it up.

    All of this led me to replace the spark plugs, MAF, and now finally the HPR. So after changing the HPR, I now am now getting rich error codes primarily on one bank but sometimes both with a similar reduction in error codes as the tank pressure drops. Below 1/2 full tank I don't seem to be getting codes at all which is an improvement.
    The van runs perfectly fine and only has 72k miles on it. Does anyone have any suggestions where I should look next?
    Any help would be much appreciated. Thanks,


  • #2
    Im not familiar with BAF systems.
    I dont know for sure but i would check the pressure at the bleeder, if you have one, at the rear of the intake manifold to see what the pressure differences are when tanks are full or quarter full.
    Should not matter what the tank pressure is. The regulator is supposed to supply a steady 100psi (i think) to the rails regardless of tank pressure.
    Interesting that you had lean to rich changes after changing out the HPR.


    • #3
      Thanks for tip and I will definitely take a look at that. It's definitely been a head scratcher and at this point the only thing that I feel confidant in is that it is somehow pressure related.


      • #4
        Are you getting any codes other than rich and lean?


        • #5
          The only codes I have gotten are rich or lean. Since changing the HPR I only get rich codes(both banks) and the check engine light will turn off on its own when my fuel gauge drops to about 3/8 full. The first code after filling has become predictable in that it will come shortly after the first time it cools down. In other words I can fill the tanks and then continue driving without a code but when I stop and the engine cools off, I will get a rich code shortly have starting/driving it.



          • #6
            I suppose the remaining culprit is injectors. If you are able to check the fuel rail pressure, as suggested by greenmeanh1, it should remain relatively constant no matter the tank pressure and vehicle status (engine running or parked up). A leaky injector would slowly relieve pressure in the fuel rails & low-pressure side of your fuel system if stuck open. You would also likely smell some natural gas under the hood. Then, when you start up the engine again it will run rich for a moment, possibly long enough to throw the code, especially if the injector is sticking open for a number of cycles before agian behaving. Of course, this would also tend toward misfiring - but you aren't getting that code so this really is a head-scratcher for sure.

            Since you have codes on both banks, if my theory is correct, then you have more than one problem child to replace.

            I think that by 2010 BAF had transitioned from the NGI1 to the to the Bosch NGI2 injector, and these are relatively easy to find.
            You will know if its the NGI2 because it requires a BAF-supplied spacer cone to provide enough length to inject down into the hole.


            • #7
              Thanks for insight! I will take a look at the injectors and get back to you on what I find.