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  1. #1
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    2 out of 2 members liked this post. Reputation: Yes | No

    Injector Duty Cycle

    Hey,


    first of all: i'm from germany, and its very difficult for me to write about those complex things in english, i hope you can understand me Click here to enlarge

    i drive an 2009 E90 335i.

    My Problem is, that the car is jerking under hard acceleration at ~ 3000rpm.

    The first thing i did was to change the spark plugs. But the car is still jerking...

    Now i did some measurements with INPA (see screenshot below). The first three lines are "duty cycle".

    I found some similar screenshots on the internet. But there is the duty cycle from all cylinders much higher than mine. (Mine ist 37,9% - 42,5% an the others are 47,3% - 51,1%)

    I'm no professional with those technical details, can this cause my problem? If yes, how can i fix it? Do i need new Injectors?

    Maybe anybody with an stock 335i can do the injector measuring with inpa and can post the screenshots?!

    Thanks

    Click here to enlarge

  2. #2
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    Click here to enlarge Originally Posted by maninblack Click here to enlarge
    first of all: i'm from germany, and its very difficult for me to write about those complex things in english, i hope you can understand me
    Your English seems to be fine, I don't think anyone is going to have any trouble understanding what you mean.

    Now let's get you some help.

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    It looks like you are nowhere near any limits, definitely not for injector duty cycle.

    Is your car modified at all or completely stock?

    The fuel injectors on the N54s are notorious for problems as many will undoubtedly reply but jerking under load can be from a lot of different things. You need to get a proper diagnosis before thinking about replacing parts.

    Is your car's dashboard showing any warning lights? Do you have access to a diagnostic device to read trouble codes?

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    Hi,

    the car is completely stock!
    I have Interfaces and Software to read out trouble codes. But the is no code stored! And no warning lights in dash :-(

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    Click here to enlarge Originally Posted by maninblack Click here to enlarge
    Hi,

    the car is completely stock!
    I have Interfaces and Software to read out trouble codes. But the is no code stored! And no warning lights in dash :-(
    How many km on the car? Does it start and run rough/shaking when cold or first started after being off for hours?

    I'd say check the spark plugs if you can. You need a particular uncommon spark plug socket for that though. If you have one or more plugs that look oil or carbon (fuel) fouled, that may reveal bad fuel injectors (common) or bad coils (happens, but not as often as injectors). But it could be many other things as well from a clogged fuel filter or dying fuel pump to leaks in the intake piping somewhere (boost leak).

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    Hi,


    the car has ~ 88.000 km. The Spark Plugs are new. As i changed the Spark Plugs, there was oil at the third spark plug...
    Some people bet on the HPFP, but the car starts immediately after i press the button and runs smooth...
    I got 4 Injectors and a HPFP very cheap, so i think i should change them and try it...

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    Hm maybe it's important jerking is only noticable in 4th gear or higher. Sometimes more sometimes less... Sometimes in 3th gear too...

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    I guess it will throw a missfire or hpfp code at some point, since you are on a stock tune it might be harder to push the car hard.

    Do a compression test since you had oil on no 3 spark plug?
    Click here to enlarge
    997.1 tt
    Kline 200cell exhaust
    997.2/GT2RS IC's
    Cobb E85 custom stage3 tune by Mitch
    ID1000 injectors
    Sachs stage 2.5 clutch

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    I have INPA, but i don't have this injector menu. What's version you have?

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    Click here to enlarge Originally Posted by maninblack Click here to enlarge
    Hm maybe it's important jerking is only noticable in 4th gear or higher. Sometimes more sometimes less... Sometimes in 3th gear too...
    Yes, that is important... Can you describe how "hard" the jerking is? Or maybe through up a quick video? Since it's 4th gear (sometimes 3rd) - and based on what I have read, it sounds like carbon buildup or the wastegate vacuum line... How many km do you have on the car?

    In regard to the duty cycle, this is dynamic - at idle this graph will read differently than at full load in 4th gear. It's hard to compare these graphs across two cars without them running at the same exact RPM + Gear + Speed.

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    There are no error codes stored!


    The Screenshot was made with running engine at idle rpm.


    INPA Version should be inpa EA-90x, i'll have a look for the menue path...

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    A pull in higher gears would push the fuel system harder, and since the hpfp is crap in the n54 I would still guess its the culprit...but guesses doesnt help.

    check all vacumlines, do a simple compressiontest, maybe try to get a camera to inspect valves for carbon build up.
    Click here to enlarge
    997.1 tt
    Kline 200cell exhaust
    997.2/GT2RS IC's
    Cobb E85 custom stage3 tune by Mitch
    ID1000 injectors
    Sachs stage 2.5 clutch

  13. #13
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    But keep provoking the issue to see if you can get it to throw a code...
    Click here to enlarge
    997.1 tt
    Kline 200cell exhaust
    997.2/GT2RS IC's
    Cobb E85 custom stage3 tune by Mitch
    ID1000 injectors
    Sachs stage 2.5 clutch

  14. #14
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    IDC is low at idle and low load scenarios since it's easy to hit stoich. Have you monitored while WOT? I bet it shoots up.

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    i bet if you put a tune it will throw an error straight away. without codes hard to troubleshoot.
    07 335i AT - MOTIV 750 - MHD BMS E85 - BMS PI - JB4G5 - Okada Coils - NGK 5992 Plugs - Helix IC - Stett CP - Custom midpipes with 100 HJS Cats - Bastuck Quad - PSS10 - QUAIFE LSD - BMS OCC - Forge DVs - AR OC - ALCON BBK - M3 Chassi - Dinan CP - Velocity M rear Toe arms - Advan RZ-DF - LUX H8 - Level 10 AT upgrade
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    1 out of 1 members liked this post. Reputation: Yes | No
    i'm driving around with this issue since 7 months without an error code.
    maybe i should dismount the intake manifold and have a look at the intake valves, if they're coked?


    next week my new hpfp should arrive...

  17. #17
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    Just FYI, these values are available on the AP for datalogging for those interested.
    Click here to enlarge

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    Maybe I got it.
    Today I swapped injector 1-4 with new ones, cleared adaptation values and made a test drive.

    now I can reproduce an error, under hard acceleration I get "verbrennungsaussetzer, zylinder 6" -> "burning misfires, cylinder 6"

    So tomorrow I will put a injector, which I removed today, in cylinder 6 and swap the coil with another cylinder...

  19. #19
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    So, swapped injector 6 with old injector 2 (which i removed yesterday)
    and coil 6 with coil 3, cleared adaptation values and made a testdrive...
    The error is still the same.


    The Spark Plug is ok, i replaced them before 2000km, and the problem existed before.


    Maybe the Problem is the HPFP? Because of Cylinder 6 is the last in the row an the way from HPFP to Cylinder 6 is the longest?
    What do you think about it?


    Or maybe it isnt a good idea, to clear adaptation values and then hit the gas?!


    I hope anybody can help me

    PS: Today i got the error 2times. 1x at 3200rpm and 1x at 3616rpm
    Last edited by maninblack; 03-15-2013 at 06:33 PM.

  20. #20
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    Bump, let's get him some help.

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    How many miles since a valve cleaning? Seems like you're doing everything right assuming you coded the injector and the old one you used wasn't going bad. Keep hammering away, maybe check that plug... could be fouled from whatever was going bad or may just be bad.

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    Hi,

    the valves were never cleaned. For sure, the Injectors are coded well!

    I checked everything twice... Plugs, Spark Plugs ...

  23. #23
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    walnut blast them and see if the problem is still there? It should be done anyways...

  24. #24
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    I think this says everything...

    But i'll change the HPFP nevertheless, because the most of the work is done
    and i already have a new pump.

    Now i have to find a garage, which can clean the valves... i think this is difficult in germany..
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