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  1. #1
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    Misfire Diagnosis Question - Fuel Injector

    OK - recently started getting some cold start misfires. Kind of feels like 1 of 6 cylinders is missing. Pulled codes and got a misfire on cylinder 3 and later triggered a misfires on multiple cylinders code.

    I have a couple coils and 1 injector on the way. From other's experiences, I am guessing I should move the cylinder 3 coil to cylinder 2 and see if the misfire moves first? If not, it is likely the injector?

    The only other fact I have is when swapping my spark plugs 5K miles ago, cylinder 1's plug had a lot of soot on it and smelled like gas after pulling it. Which would make me think cylinder 1's injector was the leaky one in the bank (cylinder 3s looked fine). From reading posts it looks like BMW just replaces all 3 injectors in the affected bank.

    Any thoughts on how to proceed here? I guess I can just order 2 more injectors and swap them in, but that really just feels like guessing since I am somewhat certain the issue lies one 1 of the 6 cylinders.

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    The diagnostic tree shows to replace only ONE injector if only ONE cylinder in the bank is misfiring. If more than one per bank are misfiring, then replace all three.

    Page 8 in the Diagnostic Fault Tree here would be of interest to you.

    B125506_N54_Engine_Diagnostic_Fault_Tree_01_06_11.pdf

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    Since they're happening on cold start I say bad/leaky injector
    Click here to enlarge

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    I thought injector too, but not sure if it is cylinder 1 or 3. The amount of fuel injected depends some on the A/F ratio seen by the O2 sensors in each bank. If cylinder 1 had a ton of fuel pooled up in it because the injector was leaking, could it make the bank appear to be running rich and cut enough fuel from cylinder 2/3 to cause a misfire on those cylinders? Maybe I am overthinking things and it is just cylinder 3.

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    bump

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    Most likely the injector is bad..
    I’ve been there and done that unfortunately and ended up purchasing all new injectors and coil packs..

    After the first injector went bad then another one started acting up.. Never had any misfire codes but if the plug is covered in soot then my money is on the injector..

    How soon until your replacement parts come in?
    For Sale:

    - NX Express complete wet kit with Plug & Play fuel adapter for BMW 335i

    - FBO parts here LINK


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    Monday. I have somewhat decided I am going to replace the injector on cylinder 1 first and see if that fixes the issue. I am going to replace the coil on cylinder 3 as well. If I need to go back and buy 2 more injectors to do the whole bank later, then whatever. It is only money! :0

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    I also had misfires on cold starts along with long engine startup, usually 8 seconds for the engine to start. When I took it in to the dealer on wed they had to replace all 6 injectors. Now the car starts right up, smooth idle and no more misfires.

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    Click here to enlarge Originally Posted by Booyaazaa Click here to enlarge
    I also had misfires on cold starts along with long engine startup, usually 8 seconds for the engine to start. When I took it in to the dealer on wed they had to replace all 6 injectors. Now the car starts right up, smooth idle and no more misfires.
    It's interesting that BMW did an injector recall but the failure rate is still so bad. Sounds like a class action suit in the making...

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    OK, so I finally got around to messing with this. At this point I have only replaced the coil on cylinder 3. That seems to have fixed *most* of the issues. At points it really did feel like a coil failure (which I am very familiar with being a prior VW 1.8T owner). I was skeptical that was the root cause, but things have been much better since changing the coil on Sat.

    I still think that the cyl 1 injector is leaky. All of my injectors are the xxxxxx261-07 variety, except cylinder 5, which is a xxxxxxx261-08. The new one I ordered is now a xxxxxxx261-09.

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