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Massive Bang I can't figure out

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by s-in-la, Jan 19, 2013.

  1. s-in-la

    s-in-la Junior Member

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    I have 2009 Prius, 32k miles, I bought it two years ago when it had 21k miles, no troubles other than needing to replace the starter battery about two months ago. I live in SoCal, it was about 75 degrees today. I drove it about an hour on the freeway, it then sat for 4 hours, then drove it home. After about 15 minutes driving I stopped for lunch for about 30 mins, then drove the car to the othe side of the parking lot and stopped. I got out of the car to look in a store window, got back in about two minutes later, started the car, then BOOM, the car shakes as if it's been hit by a coconut or soccer ball. Scared the crap out of me, but looked around, didn't see anything amiss, put the car in drive then BOOM again. The whole car shook again as if it had been hit. Since I was in an empty part of the lot, I didn't want to get out, so I drove to the other end where there were a lot of people with pets and kids and stuff. The BOOM continues about evey 30-60 seconds, until I turn the car off. I restart, drive it around the lot once, still it makes the noise, but it doesn't seem to impact the driving other than scaring me a bit. Not sure if the boom is less or if I'm just more used to it now.

    I get out, open every door, the trunk, look underneath, there is nothing amiss. I get back in, start the car, and try to figure out exactly where the sound is coming from. It goes off every 30-60 seconds, but seems to be taking longer between them. It's coming from the engine. I prop the hood. I never hear it when I am outside the car, only inside. It happens a few more times, and I'm about to call AAA, but while I'm waiting to pinpoint, it stops. Whole thing probably lasted 5-7 minutes. I wait, it doesn't start again, and I start gingerly driving it around the lot, no noise. Eventually I drive it home, about 45 minutes freeway and street driving. No problems at all.

    I have no idea what this was, or if it's something to bring in, I didn't happen much after releasing the hood, so I don't know if there was a crazy air pocket or something, but I'm a little afraid of what might happen while driving I the future. I'm it kidding when I say it was powerful enough to make the car shake.

    Any ideas at all???
     
    #1 s-in-la, Jan 19, 2013
  2. bobodaclown

    bobodaclown Member

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    Similar thing happened to us on the highway. Sounded like a gun shot. Only one. We were driving about 75mph. Pulled over all was ok. Continued uneventful.
     
    #2 bobodaclown, Jan 20, 2013
  3. dorunron

    dorunron Senior Member

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    The sound you describe reminds me what it sounds like when you are going down the road in a old car and turn off the ignition, then turn it back on. What happens then is that the car backfires through the tail pipe. It is very loud. I did it one time to many in a old Ford truck and ruptured the muffler.

    If the Prius continues to boom, you might want to have it checked for misfires or backfires. To me it sounds like the plugs are not firing all of the time, and the collected fuel is being ignited further down the line. Chances are I am completely wrong in my guess, as it a guess. But it does sound like you are suffering from what is commonly called a backfire. Finding what is causing the backfire should cure the car once and for all. A good scanner should help you immensely. If nothing shows up (DTC's) with the scanner, then a trip to the stealer would be advised.

    Ron
     
    #3 dorunron, Jan 20, 2013
  4. GrGramps

    GrGramps Active Member

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    Ron, I have been waiting for someone to suggest a backfire since I cannot imagine anything else that could make the noise that's described. Take that back - a tire blowout makes a big bang, but you would have to be dead to not realize what had happened.
     
    #4 GrGramps, Jan 20, 2013
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  5. dorunron

    dorunron Senior Member

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    What can I say, I am an old school type of guy who drives a new hi tech machine. Computers are great, but sometimes it still takes common sense to fix them.

    It will be interesting when the OP finally determines exactly what the cause of the boom is.

    Ron
     
    #5 dorunron, Jan 20, 2013
  6. s-in-la

    s-in-la Junior Member

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    Thanks very much! One question though. I tend to think of backfires as coming from the exhaust and I definitely was able to pinpoint the sound from coming under the hood. I would say behind the gps or gloveboox area. However, you are right, that is exactly what it sounded like...

    Do you think if it doesn't happen again I should still take it in? My local dealership costs a fortune for everything...
     
    #6 s-in-la, Jan 21, 2013
  7. nh7o

    nh7o Off grid since 1980

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    Backfire would indicate unburned gas in the tailpipe. That would be something that the mixture sensing circuit in the exhaust pipe would pick up, and give some sort of DTC. It would be a good thing to see if a scan comes up with anything before making any decisions.
     
    #7 nh7o, Jan 21, 2013
  8. dorunron

    dorunron Senior Member

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    I would suggest you get someone to check for DTC's (codes). If there aren't any, then the next step would be a mechanic if you can not pinpoint the problem. Most autoparts store have code readers. They may or may not pick up everything from the Prius. The dealer has the more sophisticated stuff. As you have already pointed out, they do tend to be expensive.

    If you do find out what the problem and remedy is, please post back to the forum as this will help the community as a whole.

    Ron
     
    #8 dorunron, Jan 21, 2013
  9. SteveLee

    SteveLee Active Member

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    The autoparts store, Advance, Autozone, O'Reilly's, sounds like the best first option. They will hook up the scanner for free. They may not get all the codes of the Prius but they can get many of them. It doesn't sound like something to ignore. The backfire makes sense, especially since you say that is exactly what it sounds like.
     
    #9 SteveLee, Jan 21, 2013
  10. nh7o

    nh7o Off grid since 1980

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    The generic scanners will read the main engine and emissions control info, which should give the air/fuel ratio sensor.
     
    #10 nh7o, Jan 21, 2013
  11. fuzzy1

    fuzzy1 Senior Member

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    If a plug is misfiring, causing fuel to be dumped downstream to cause a backfire, shouldn't this throw an immediate Check Engine Light (CEL)? My old car has signaled a misfiring cylinder several times, despite not missing enough to cause any backfire or even a noticeable stumble.

    Can a 'backfire' also occur in the intake manifold? Not sure if that would trigger a CEL.
     
    #11 fuzzy1, Jan 21, 2013
  12. bobodaclown

    bobodaclown Member

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    It's happened to me only once in 12,000 miles of ownership. I'll keep an eye on it and report back if I have any follow up.
     
    #12 bobodaclown, Jan 21, 2013
  13. s-in-la

    s-in-la Junior Member

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    Thanks everyone! I have to bring it to the dealer for some recall repairs anyway, I'll ask them to run a check. I'll post an update once I find anything else out. As it happens I had another long drive today, and no troubles at all...
     
    #13 s-in-la, Jan 22, 2013
  14. s-in-la

    s-in-la Junior Member

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    Hi everyone, I took my car into my local dealership today and thought I would provide an update (such as it is). Let me say to start that I really dislike my dealership and only use them when I have to, and I never quite believe half of what they tell me, and they charge a fortune for everything. That said, I went in today to get the steering shaft and water pump repair that are covered under the recall. I was fortunate to be able to talk to the mechanic directly about the backfiring, which he said he would check out, but I could tell that the intake person definitely thought I couldn't tell a backfire from a griding brake, so who knows how seriously they took any of it.

    Overall they recommended replacing the engine air filter, and I also had a cracked drive belt. I didn't speak to the mechanic again, and the intake person told me "he couldn't replicate the sound" (since it only happened in that one timeframe 2 weeks ago that's not very surprising).

    So, my 2009 Prius with 32k on it now has a new 12v starter battery, a new drive belt, and a new air filter (not that I mind that one much). Oh, and one of my tires is apparently bald, and they recommended I get 2 new tires (I'll be taking that to my local guy to look at). Did I mention my daily commute was less than 4 miles round trip? seems like an awful lot of wear and tear on a car I drive less than 5 miles a day on average.
     
    #14 s-in-la, Jan 26, 2013
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  15. JMD

    JMD 2012 Prius 4 Solar Roof

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    Hopefully that resolves the issue.

    32K miles seems low to replace tires but perhaps the previous owner did not take care of them via rotations etc.
     
    #15 JMD, Jan 26, 2013
  16. rcf@eventide.com

    [email protected] Member

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    Just to back up Mr. DaClown: This happened to me, too. Driving at 55mph on the Hutch (CT) I could swear someone had shot at me. Reached destination with no further events, no problems, and definitely, on careful inspection, no bullet holes or other obvious cause. Mysterious to this very day, never happened again.

    Richard
     
    #16 [email protected], Jan 26, 2013
  17. bisco

    bisco cookie crumbler

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    how much was the drive belt? that seems premature.
     
    #17 bisco, Jan 26, 2013
  18. s-in-la

    s-in-la Junior Member

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    The belt was $30, the labor to install $110
     
    #18 s-in-la, Jan 27, 2013
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  19. ToyotaPrius2005

    ToyotaPrius2005 Junior Member

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    go find a different dealer.. I have the same thing with my local Toyota dealer...dishonest..found a different dealer haven't had any more drama.
     
    #19 ToyotaPrius2005, Oct 9, 2013
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