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Thread: Pop pop pop bang bang pop. Is it the obvious?

  1. #1
    Guest MrPARR's Avatar
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    Pop pop pop bang bang pop. Is it the obvious?

    Been having a bit of a annoying problem, car is running all stage 3, but normal t28, mongoose 2.5, new ngk coppers at 0.8 gap, injectors newly cleaned/flow tested and running a tank of vpower.

    All happy off boost, starts fine when cold, comes on boost smooth and idles fine, but once it's on boost and really getting going it very quickly pops and bangs, and hesitates while it does it.

    Googling about people are saying it's most likely rings, but car doesn't smoke, and breathers are fine. Searching here most say boost leak, which makes me wonder as the car as the boost comes on gets a slight second whistle but thought that was just air on the throttle body as not driven it in a while.

    Avcr says -450 when idling, it does go up once warm to -490-500, which says exhaust valves but from what I read that just causes cold start problems, but mine fires up first turn when cold, normally takes a little longer when warm.

    Gave it a bash on the way home, avcr max settings were 1.20 hit, 5500revs max so it's happening around 4500 onwards, you can slightly drive through it but not taken it to the limiter incase of damage.

    If this was your car, what would your next move be?

  2. #2
    Banned sideways14a's Avatar
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    Quote Originally Posted by MrPARR View Post

    what would your next move be?
    I would be expecting my subscription to "Boost leaks Monthly" to be landing soon.

    Yup, it sounds like a puff leak

  3. #3
    Flamethrower Turbo Gav's Avatar
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    Wideband would be good after the obvious normal checks....doubt very much its the rings.
    **Currently breaking**
    RX-8 191, RX-8 231

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    Ditto, had this myself, spray brake cleaner or similar around your pipework on idle, when revs increase thats your leak. Could be harder to find if it only leaks on boost

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    Banned sideways14a's Avatar
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    Pressure test it

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    Quote Originally Posted by Sideways14a View Post
    Pressure test it

  7. #7
    Guest MrPARR's Avatar
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    Can I substitute brake cleaner with carb cleaner? That way I can give the AFm a squirt as well while I'm at it. :-)

    Just been reading Threads on pressure testing which seems easy enough, block turbo block plenum fill through hole on ic pipework. Will have a pop at that on weekend, just gonna park it up till then as it's making me feel down. :-(

    Will the increase in revs be obvious when sprayed?

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    Yeah you can use anything thats flamable or uses a flamable propellant. Rev rise will be obvious
    You can test ic pipework by pressuring with a tyre inflator, just make up a bung that fits in the turbo outlet silicone/rubber pipe, then fit a tyre valve to it. Im sure i read somewhere of someone using an aerosol can lid for this

  9. #9
    Guest Daveyboy20's Avatar
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    Make sure all your intercooler pipewok is secure, I had this on my old s13 and my silicon hoses were all loose. They are definitely not symptoms of piston ring wear!

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    Guest MrPARR's Avatar
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    Right, went out and bought myself some brake cleaner - Said on the pack that it leaves no residue etc

    Sprayed all pipe joinings/intercooler while the G/F sat in the car watching the revs, not even a blip in the revs. =/

    Drove it about 50 miles over the weekend, had the boost turned to 0.8 and it never stumbled once from the few bits of boosting I did - It did feel a big heavy tho, not 100% free revving.

    Today it has started making a new noise - I can hear it spooling and start to boost from the left hand side as normal, and then there is a much high pitched noise come on from the right hand side, like a second turbo but the pitch is higher - Boost still seems to be fine but didnt push on much with the noise. V_V

    Think the only way I am going to find this bugger is pressurise my intercooler pipework - Tightened all my current clamps but made no difference... Everything is now pointing to a boost leak under pressure - The most annoying kind.

    Bugger it! :-( Far to cold to be working on the car - Bloody -5 this morning

  11. #11
    Guest mattlake's Avatar
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    yep, sounds like aboost leak under pressure im afraid, and they can be a pain to find, unless you take the bonnet off and have someone sit in the bay while you boot it around

  12. #12
    Guest ANDY black s13's Avatar
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    i took of my intercooler and all pipe-work,blocked off all the ends and fitted a car tyre valve in to a section of hose to block of the cold start feed.
    filled my bath lol and with the whole thing pressurised to 15 psi via pump with gauge,placed in bath.
    found leaks in the core of the cooler and the BOV aswell,if i let the pressure down to say 10 psi they disapeared??,back up to 15 psi da da worked for me mate!

  13. #13
    Guest Hugh Janus's Avatar
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    did you have a good look around the intercooler boost pipes (especially the one that go into and out from the IC

    i spent ages looking for a leak and found nothing (despite looking at all the pipes....just not very well clearly)

    i then found this tucked away right out of the way, behind the under tray


  14. #14
    Guest MrPARR's Avatar
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    Holy chapsticks - Did it still run like that?

  15. #15
    Guest Hugh Janus's Avatar
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    Quote Originally Posted by MrPARR View Post
    Holy chapsticks - Did it still run like that?
    yeah ran ok for ages was only on full boost that it really played up, i knew it was a boost leak somewhere just could not find it, i dread to think how much fuel i wasted looking for it

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    is it continuing to rev when banging?

    i think you gotta check fuel pump

  17. #17
    Guest JJ's Avatar
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    Happens a lot

    Or the hoses that connect the intercooler to the piping.
    Sitting chucked away in the front bumper, hard to spot...

    Get is pressure tested as some said before

  18. #18
    Guest MrPARR's Avatar
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    Yup will continue to rev, and will rev through it if going gentle and not boosting hard. I think it must be a boost leak now, my first real boost leak and its really pissing me off more than it should - Hence my new, super massive thread asking for every piece of boost related advice anyone in the whole world can offer so that once I fix this gawd darn problem no one else will ever suffer from what is the most annoying problem ever.

  19. #19
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    i had same problem 2 years ago , after i changed my fuel/gaz pump , problem was solved.

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