BACKFIRE during crank, wont start!!
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This is a discussion on BACKFIRE during crank, wont start!! within the General Maintenance, Troubleshooting & Accidents. forums, part of the Tech & Modifying & General Repairs category; So i have searched all over the web for at least ONE forum about my problem and have found nothing ...

  1. #1
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    BACKFIRE during crank, wont start!!

    So i have searched all over the web for at least ONE forum about my problem and have found nothing so i decided to start my own. I was getting desperate ad searching similar issues with EVO's and other tuners.


    Queso this is whats happening, RANDOMLY one morning i decided to take out my car out (since i rarely drive it anymore because i have spent so much money on the build i like it to sit pretty in the garage).
    When trying to start my car it would crank and crank and suddenly **BANG!!!** loud pop out the exhaust. Now, i have been fabricating my own exhaust parts too and as of now its just the down pipe, so when i heard that im pretty sure i crapped my pants because it sounded like a shotgun went off under my A**. The fuel pump primes i can hear it, so i dont think its fuel related. i decided not to crank it anymore because my neighbors think i like to shoot guns in my garage now. I am so confused. From what i have read so far i have narrowed it down to a few ideas,

    A. Timing some how got out of wack? idk how tho since it was driving just fine when i parked it.
    B. Coil packs are bad? weak spark but definitely getting fuel.
    C. Something with the ignition? but i think im going to rule that one out.
    D. Reason for the big bang is because im getting WAY WAY to much fuel the i can ask for.

    Has anyone ever seen or heard anything like this?

    Engine: EJ25 block and heads,
    CP forged pistons
    Manly rods
    STi crank
    And all sorts of goodies that i get to lazy to type out.

    Im really hoping one of my fellow AWD's can help me figure this one out.

    Any ideas at this point will very helpful before i have it towed.

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  3. #2
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    No one has the slightest idea?

  4. #3
    Subaru Newb MainFrame's Avatar
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    It really could be any number of things.. timing, spark, fuel. It could be out of time, you could have an electrical fault somewhere in the wiring harness or connectors, broken wire, short, bad ground.. you could have an injector sticking open or closed. There could be something going haywire with the ECU. Perhaps a bad sensor..

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    Registered User StimpyV2's Avatar
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    If this was my car for something like this id flat bed it to an expert.

    04 WRX Wagon - Battle wagon

  6. #5
    Moderator Donkey's Avatar
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    Stuck injector/s?
    Resident Adviser @ WTF Tuning, LLC
    2002 FORESTER S
    1998 FORESTER S




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    thank you for the reply, i think tomorrow im going to pull the coil packs and injectors. if its the timing im really praying its not bent valves, tho i really dont think it is considering the car was running perfectly and as smooth as can be when i parked it. ill update you once i have done that. my question is, what could cause the ECU to freak out like that IF it were that?

    has anyone ever had issues with the 1000cc dynamic injectors?
    or anything similar to my issue?
    Last edited by 18GXTWRX; 06-18-2014 at 08:10 PM.

  8. #7
    Subaru Newb MainFrame's Avatar
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    ECU could mess up from an electrical component failure, both heat and vibration can cause that. Or moisture can cause things to corrode and fail.. manufacturing defects are always possible.. or some kind of electrical overload from static, lightening, welders, or a short in the car's wiring harness.


    I had thought possibly burnt or bent valves could possible cause that.. but they would have to be messed up really bad, like broken off.

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    Subaru Newb MainFrame's Avatar
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    Have you tried changing the plugs? Make sure they're not broken, or improperly gapped?

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    Ill be sure to check the plugs. Wouldnt you think the car would be running like crap, (rough idle ect) if the valves we bent prior to even PARKING the car? If any of these things dont work im going to have to take it in for a compression test.

  11. #10
    Subaru Newb MainFrame's Avatar
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    It's possible, though probably not likely, that something broke the first time you tried to start it and it didn't work.

  12. #11
    Registered User UEDan's Avatar
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    So you didn't try and crank it again. And you say you just have a down pipe... No muffler?

    You say you didn't drive it for a while. That could have cause the battery to go down just enough to cause a weak spark.
    And since the car is cold you were in the rich warmup phase.

    Dare I say try and start it once more?

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    No muffler is correct.. am i causing any damage when it back fires? Battery is brand new (somewhat)... But i suppose i can attempt to give it a jump just for good measure.

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    Pulled the coils and plugs, inspected and cleaned...Went to turn over, no backfire...and about 20 mins of trying to start it..finally turned over. whew.......CEL now, ill get the code tomorrow. Thanks for all your suggestions.

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