By on July 17, 2013

TTAC commentator bumpy ii writes:

I have a 2007 Hyundai Accent 5-speed manual hatch. When I’m driving, sometimes I’ll hear a little ‘psssht’ noise as I pass through 2500 rpm. It almost sounds like a tiny blowoff valve under the car.

My thinking is a small leak in the flex coupling on the exhaust, though it seems odd that it would only happen at a specific rpm.

Sajeev writes:


But seriously, I have no idea why that’s happening.  First I was thinking about that exhaust leak, but (like you said) that wouldn’t be RPM specific. Or perhaps an intake tube leak, but one significant enough to make that much noise wreaks havoc on a computer’s ability to control the air/fuel ratio.  Maybe an EGR thing, perhaps a vacuum line gone bad?  But the odds of that being “bad” enough to make that sound?  Not likely.

Did you install an aftermarket intake tube assembly?  Or even just a K&N filter?  Try returning it to stock and see if that does anything.

If that’s not the case let’s go with the exhaust leak.  Go to an exhaust shop and put the Accent up in the air: perhaps they will see or hear something that will explain the problem. What say you, Best and Brightest?


Send your queries to [email protected] Spare no details and ask for a speedy resolution if you’re in a hurry…but be realistic, and use your make/model specific forums instead of TTAC for more timely advice.

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41 Comments on “Piston Slap: An Accented Whooshing Sound?...”

  • avatar
    Freddy M

    A buddy of mine has the same model Accent. I’m not sure he ever experienced the same problem, but he did mention once that he needed the throttle body assembly replaced. I’ll see if I can ask him if it was at all related to your problem.

    Also, that riced out Accent in the photo looks pretty cool. I’ll suggest he do that.

    • 0 avatar

      Please tell me you’re kidding. One look had me reaching for my “Lobotomizer” from WWZ so I could beat this MFUGLY thing off the page.

      • 0 avatar
        Freddy M

        I dunno, I really like it :) And I thought the shape of this Accent was really nice, much nicer than the mini-minivan look that a lot of subcompacts have nowadays.

        Although keep in mind, a list of cars I think look great also include
        – Honda Element
        – Nissan Cube
        – Nissan Juke

        Maybe I need a “Lobotomizer?” :P

  • avatar

    Leaking flexpipe… I’d almost bet money on it. Get a fine pin hole in there and BAM… whooshing sound.

  • avatar

    I’m going with the exhaust leak as Sajeev said. That was my first thought. I had a Honda Prelude that had a similar problem at around the same RPM range. Sure enough, exhaust leak.

    • 0 avatar

      Ditto. My first Altima had the same type of problem, at certain RPM levels it got really loud. One of the spacers/insulators in the exhaust system was damaged.

  • avatar

    I had that happen for about a week. Later, my mechanic discovered my neighbor’s cat carcass rotting between the transmission and the wheel well. It was so badly decomposed I couldn’t even use it’s fur for a decent throw pillow.

    • 0 avatar

      VanillaDude is back, raw and uncensored!! Welcoma back man!

    • 0 avatar

      Welcome back!!!! Thanks, Derek and Jack!

      • 0 avatar

        Thank you very much.

        I would like to submit for review my past year living without TTAC and my life being locked out from hanging with my favorite people. Curbside Classics has been a lifeline during that time and I will continue to enjoy that site daily, but I have to thank everyone at TTAC for getting me out of the Cooler. Steve McQueen and I got along quite well in the slammer, but he is a complete ball hog with that baseball and baseball mitt of his.

        I won’t even go into what he uses that mitt for besides catching, but you can imagine that a guys gotta do what a guys gotta do!

  • avatar

    Beans? Could it be from eating beans?

  • avatar

    Exhaust leak for sure. It becomes apparent only when you build up exhaust pressure in the pipes/manifold.

  • avatar

    Not sure it is a problem.. If there is no CE light, I wouldn’t worry about it.

  • avatar

    I’m amazed that Mr. Metha’s advice wasn’t to either drop an LSX in it or go buy a Panther. :P

    Since it is a manual trans model, let me ask: Does it happen in every gear as you pass 2500 RPM?

  • avatar

    Perhaps a vacuum leak? My best guess if it isn’t an exhaust leak.

    The Accent in the photo is amazing to what can be done with this little guy, but no matter how you dress one up, that egg-like back end aft of the door is a deal-killer for me. That’s why I refer to these as “egg cars”, because that’s what they look like!

    EDIT: Gee, Dan, looks like we’re back in traditional form, doesn’t it? Look at that timing!

    • 0 avatar

      I was thinking the exhaust leak, or… did these have the variable-length intake runners? Could just be that. I know more and more manufacturers have been doing that even on the cheap cars. The current Accent is, so maybe the last might have, too.

      As for the body kit, a bit much for just a kit, but it’d be a fun project with the right engine. You’re not alone hating the way the ass-end of this car bubbles out. To me the way the hatch bubbles out past the tail-lights is like looking at a diaper. Still, beats the sedan, and you get the SE package with all the cool “go fast” bits like a slightly lower and firmer suspension (new springs and shocks, maybe roll bars), the widest wheel/tire combo a subcompact offered at the time, and a B&M shifter. Yes please… now for 10 or 20 more hp, though I wish it was as stripped of weight as the “Blue” model.

  • avatar

    For the record: the answer is always LSX-FTW. I just don’t feel the need to cram this truth down everyone’s throat on a regular basis.

    Could you imagine that Accent up at the top with an LS4 swap? Oh maaaaaan.

  • avatar

    Might be a good idea to go down to your local hardware store, buy a propane tank, a blowtorch nozzle, and a piece of tubing that will fit over the nozzle tight. then, start the car, open up the gas to get it flowing through the tube, and let it flow over the intake piping, vacuum lines, intake manifold and associated gasket, and observe for a change in running condition. When you pinpoint a spot that affects running condition, replace that component.Cheap and cheerful.

    • 0 avatar

      The cheaper, safer, and easier method is a squirt bottle of water. I’ve tried the propane method and never had any success, but water works great as you can totally douse everything with no ill effects.

  • avatar
    bumpy ii

    Yes, it happens at 2500 in every gear, but not every time.

    One more data point: running the AC moves the noise up to around 2900 rom.

    I’m still inclined toward the flex coupling leak, but an alternate theory of mine is that the serpentine belt is worn just enough to slip momentarily at a resonant frequency.

  • avatar

    I always thought this Accent looked decent… I used to see one in a nearby Hyundai dealer in a blue that looked suspiciously like Subie’s World Rally Blue – and that particular trim Accent had a big wing, and fake hoodscoop.

    And it actually did a pretty good job of looking like the WRX.

  • avatar

    Obviously you don’t want to do this when the car (exhaust) is hot or for more than a second or two but you can briefly press a shop towel against the tail pipe, blocking the exhaust flow, and you’ll hear it at idle and can at least confirm a leak.

  • avatar

    Does the noise occur if you rev the engine in neutral while standing still?
    If so, get someone to rev the engine while you go listen under the hood with a 3 foot piece of rubber hose to act as a stethoscope and localize the noise. Jack the car up (on jackstands or a hoist) and crawl underneath if necessary. My guess is something vibrating since it is rpm related. Exhaust leaks are more throttle opening related in my experience.

  • avatar

    Had a very similar RPM-specific [around 2400] noise from an 03 Focus; Turned out to be the flex pipe, identified only after warranty had expired of course.

  • avatar

    It’s the VTEC, yo!


  • avatar
    bumpy ii

    Nine months later, and the car more or less quit doing it. Still happens every once in a while on cool rainy days. Go figure.

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