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Thread: Sniper EFI strong fuel smell.

  1. #1

    Question Sniper EFI strong fuel smell.

    Hi. My engine runs fine, however I have some issues with fuel. I'm finding it is running very rich. There's a strong fuel smell when it runs on idle. Also with idle in finding it's not running that crash hot. Anyways my AFR idle is set to target 14. I've changed this slightly to test and when I've set it to 13, its barely ran, when I changed it to 15 it also ran funny. So I'm not sure here. I'd appreciate some help or some tips to try if possible. Also, when it's running, there are quite a lot if strong fumes. And when the engine is revved, you can see a moderate amount of black fumes coming from the engine, I presume this is due to it running rich, but I thought maybe the WBO2 sensor would pick this up and fix error? I'm not sure. Does Sniper need to Learn more? If there is anything I could try to tackle this, I'd really appreciate it! Cheers.

  2. Default

    We'll need a little more information to help. Can your capture a datalog with the engine at operating temperature?
    Post the Datalog and your configuration files on this thread and the enthusiastic forum users will help review what's happening.
    Engine / Cam / Ignition system / Intake manifold details?
    Some engine / Cam / intake manifold combinations need to run a little rich to behave at idle. Ignition timing affects what AFR you can get away with at idle too.

    What was the actual AFR doing when you adjusted the target AFR?
    If the actual AFR remained rich (low AFR numbers) then you should check your Fuel pressure.
    If the fuel pressure is excessive, the injectors smallest duty cycle pulse width may let an excess amount of fuel past causing a rich condition that's unable to be controlled.

    And the good old visual check (make sure it's safe to do so). Visually look down into the Sniper while running and observe how the fuel is being distributed.
    Is fuel even between each bore or is one bore visually dumping more fuel then the others (a stuck injector for example)?
    If you're using 'progressive linkage', the front two bores will be flowing fuel at idle and the rears should not. Gary.
    351 Cleveland
    Holley Sniper EFI 4150 Super Sniper 650 with HyperSpark Ignition.

  3. #3


    Alright, I'll post these datalogs and have look in the Sniper when I get the chance later today, but I'll give some information of the engine.
    Engine: 411 Clevor V8
    Cam: I can't exactly remember, but it's a street/strip cam, won't rev higher than 6500 RPM.
    Ignition: ICE 7 amp, 1 Step. Street race ignition coil. With a booster.
    Intake: 3V CHI 225CC.
    Ignition is in charge of timing control.
    The current Target AFR is at 14. And when I change the AFR, the Sniper changes, as observed by the screen. I'll double check this when I start it later today.

  4. #4


    UPDATE: I have completed a DATA log of it running at temp, but it will not let me attach it because its a DLZ file. Any tips here?
    Also, whenever I start, it really struggles. The RPM drops very low, it progressively gets higher, then it revs too high, then it comes back down to my idle setting. So I'm not sure why this is. When it is cold, it runs very rich and smokey. Cheers!

  5. #5


    What's your base timing set at?

  6. #6


    24° at the distributor, timing curve is 4° at the ignition box. In total, it's 28° this is what my engine builder set.

  7. #7


    You must first zip your datalog and Config Files then you can post them here. Be sure to post the Config File as well. Is this a new install? The Wizard configurations are very rich, but the system Learns and leans it out.

  8. #8


    You're right! I read it needs to Learn, so I'm just going to do this for a while and see how it goes. Cheers.

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