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Gen 2, 340K, P0304 misfire and engine knock; Dealer wants to put in a new motor?

Discussion in 'Gen 3 Prius Care, Maintenance & Troubleshooting' started by CaptainSparkle, Nov 24, 2022.

  1. CaptainSparkle

    CaptainSparkle New Member

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    Hey Everyone,

    I've got a Gen2 2005 Prius, with about 340K miles (odometer has the 299,999 problem :-/)

    Driving down the interstate, the Check Engine light started flashing, so I went to pull over. As I slowed, a really large engine knock started. Since, I've only started it to get it onto tow trucks, and it was like a lawnmower: loud and shaky.

    While Getting it onto the tow truck, it threw a P0304 misfire in cylinder 4 code.

    Had the car towed to the dealer, (other mechanics were booked for weeks), and in pretty short order their response was "It has a knock, we recommend replacing the motor".

    I've seen posts here talking about EGR cleaning, and replacing plug/coils as fixes for knocks and misfire codes. Is it possible/likely that my dealer is crap, and not checking any of those options? Or is it obvious when a knock is bad enough that the engine is toast? They didn't mention anything other than "has a knock"; so I don't know if they checked cylinder compression or anything else. It is possibly the dealer checked those things, but is communicating that poorly.

    I was hoping lil' sparky would keep going another year for the market to cool down. I'm pretty mechanically inclined, but have never done any serious engine work (I can replace hybrid battery cells in my sleep at this point though ;-P) Thanks for your input!
     
    #1 CaptainSparkle, Nov 24, 2022
  2. bisco

    bisco cookie crumbler

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    how is the oil level?

    you can certainly do some more testing before making a decision. has it had all the proper maintenance?
    there is no egr on gen2

    you can try swapping coils to see if the misfire code moves. take a look at the cyl 4 plug
     
    #2 bisco, Nov 24, 2022
  3. CR94

    CR94 Senior Member

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    This might get more response in the Gen2 section.
     
    #3 CR94, Nov 24, 2022
  4. CaptainSparkle

    CaptainSparkle New Member

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    Thanks! Oil levels were on the low side when it happened; but after it sat I'm guessing oil went back into the pan, and it was nearly full. I've followed regular maintenance and oil changes-- It does burn oil a bit, but no more than typical for a car of its age.

    I'll move this to the Gen2 forum-- sorry for posting in the wrong side!
     
    #4 CaptainSparkle, Nov 26, 2022
    bisco likes this.
  5. bisco

    bisco cookie crumbler

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    report yourself and ask the mods to move it
     
    #5 bisco, Nov 26, 2022
  6. TMR-JWAP

    TMR-JWAP Senior Member

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    The check engine light on a Gen 2 flashes only for a significant misfire. First step would be to determine why there is a misfire code for cylinder 4. I have a 2008 in the family with 350k plus miles and it runs like a champ. I wouldn't replace the engine unless it's determined the knock is caused by engine damage, and not merely something like a failing sparkplug, coil or injector. (these 3 items cause 99%+ of misfire problems, with the sparkplug being the most common problem)

    A non-firing or poorly firing cylinder often sounds like someone beating on the engine with a hammer and causes significant shaking and vibration. This could be a very simple problem.
     
    #6 TMR-JWAP, Nov 26, 2022
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