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2001, Engine Vibration (missing badly), Flashing CEL

Discussion in 'Generation 1 Prius Discussion' started by DaveGoodrich, Sep 26, 2019.

  1. DaveGoodrich

    DaveGoodrich Member

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    My 2001, with 380k miles (1/3 Million!!! | PriusChat), started missing so badly that it is shaking, and the CEL is flashing. I pulled the codes, and got: P0300, P0301, P0303, P0304. It is obviously misfiring badly, and I know I shouldn't drive it until the issue is resolved to prevent damage to the cat converter, etc.

    The google has suggested the problem is most likely ignition related, either plugs or coil paks. I don't even remember when I last replaced the plugs, and I'm almost certain that the coil paks are original to the car (or are at least 280k miles old, as I bought the car with about 100k miles, and I have never changed them). So my instinct is just to replace all the plugs and coil paks. But the multiple codes suggest it is misfiring on multiple cylinders. Does this mean its not likely plugs or coil paks, since it is unlikely that multiple coils/plugs failed at the same time? Does that implicate the fuel system? Anything else I should check?

    There are pretty cheap coil paks available online (Amazon, etc.). Anybody have any experience with them?

    Thanks,
     
  2. bisco

    bisco cookie crumbler

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    any coolant in the oil?
     
  3. Brian in Tucson

    Brian in Tucson Active Member

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    Replace your MAF sensor and clean your throttle body at the same time. Plugs and coils might solve your problems. Can't hurt (except your wallet) to try. I'd get the densos that Rock Auto carries, don't forget your 5% discount. Get an air filter, too.

    Denso is OEM, by the way. I wouldn't get any other, penny wise and pound foolish. Get the best plugs, too.
     
  4. DaveGoodrich

    DaveGoodrich Member

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    I started it up after work and it ran perfectly. So it's intermittent.

    I don't think there is oil in the coolant (no foaming on the dipstick, no coolant smell, no steam in the exhaust)

    Since I got misfire codes on multiple cylinders, I like the idea of trying the MAF, since it's relatively cheap. I cleaned the throttle body already, and that made no difference.

    Thanks,
     
  5. DaveGoodrich

    DaveGoodrich Member

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    It ran perfectly again this morning, and at lunch. Yesterday morning, shortly before it started missing badly, I went to one of those "dollar car washes." Is it possible that I somehow got water somewhere I shouldn't have? I have heard of leaking cowl seals allowing water to get into the spark plug wells, etc. I didn't see anything like that, but I don't think I actually looked closely until later in the day when I had a chance to pull a COP, so maybe it had dried by then.

    Thanks,
     
  6. Brian in Tucson

    Brian in Tucson Active Member

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    Not likely, but perhaps. If it's running okay, drive it 'til it needs fixxin'.
     
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  7. DaveGoodrich

    DaveGoodrich Member

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    Started running crappy again just before getting back to the station Friday afternoon, after running well for two (9 mile) round trips to the office. I looked back at my records, and I replaced the spark plugs not that long ago, so I will wait on those. I have ordered a Denso MAF sensor from Rock Auto. We'll see if that takes care of it. Thanks.
     
  8. ronlewis

    ronlewis Active Member

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    Just for kicks, you might move the injectors and coils around to see if the misses follow. For example, you aren't getting a 302, so take the injector/coil from there to one of the other cylinders to see it the code clears on that cylinder and moves to #2. It only takes a few minutes and could pinpoint your problems to the injectors rather than the MAF.
     
  9. DaveGoodrich

    DaveGoodrich Member

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    When I pulled the codes the first time this happened, I got misfire codes on multiple cylinders, which is why I am looking at something that is not cylinder-specific.
     
  10. ronlewis

    ronlewis Active Member

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    I got that same scenario on one of my cars, misfires on every cylinder except #1, and turned out to be injectors. Bought a set off Ebay for $40 and it runs great now.

    However, my suggestion is almost a no-brainer. You can literally swap injectors/coils around in 15 minutes without getting your hands dirty. It's so easy to do, and eliminates injectors/coils as a problem, that it's kinda silly not to do it. But, throw parts at it if you feel the need.
     
  11. Josey

    Josey Active Member

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    I wish I could tell you how to check the fuel pressure in one of these buggies, but the last time I tried to look into how you do that I couldn't figure it out. Sensible and sane companies have a schraeder valve on the fuel line for checking fuel pressure. Toyota apparently doesn't count.

    But yes - as you've been thinking - if you have misfires on all 4 cylinders at once, and if this came one all about the same time, since this is a COP system (rather than having a coil pack), then you look at stuff that affects all 4 cylinders at the same time. I.e. in this case fuel or air. So fuel pressure check is #1 on the agenda. Along with cleaning the MAF. And checking for intake or other vacuum leaks.

    Weirder, less noticed and less common sources of oddities would be things like a stuck open EGR or evap purge solenoid. These can act like big vacuum leaks.
     
  12. ronlewis

    ronlewis Active Member

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    I read his post as having misfires on only 3 cylinders, which is exactly what mine was doing, and new injectors solved the problem.
     
  13. DaveGoodrich

    DaveGoodrich Member

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    Well, a new Denso MAF didn't fix the issue. After replacement, it started running very rough on the way in to work. Now getting only a 304 code. I'll try swapping the #4 COP onto another cylinder first, and see if that "moves the miss." If not, I'll try swapping the #4 injector.

    Any other ideas?
     
  14. DaveGoodrich

    DaveGoodrich Member

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    The 304 code means its the 4th cylinder in the firing order, which is the #2 cylinder (1-3-4-2), right? And the #2 is the 2nd from the passenger side, correct?

    Thanks,
     
  15. ronlewis

    ronlewis Active Member

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    My understanding is that the cylinders are numbered in order from passenger's side #1 to driver's side #4.
     
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  16. DaveGoodrich

    DaveGoodrich Member

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    Thanks,

    Can you, or anyone else, confirm that the 304 code means the #2 cylinder (4th cylinder in the firing order, 1-3-4-2)?
     
  17. ronlewis

    ronlewis Active Member

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    To be clear, I think a 304 is a misfire on #4, which is the driver's side cylinder.
     
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  18. ronlewis

    ronlewis Active Member

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    I confirmed through my SnapOn app. The firing order is 1-3-4-2, but the cylinders are numbered 1-2-3-4 from passenger to drivers side. And a 304 refers to cylinder 4.
     
    #18 ronlewis, Oct 14, 2019
    Last edited: Oct 14, 2019
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  19. ronlewis

    ronlewis Active Member

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    Do the same thing with the spark plug if the injectors don't work.
     
  20. DaveGoodrich

    DaveGoodrich Member

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    Thank you ronlewis. I appreciate the quick replies.

    Google searches also find some cases where this issue was caused by clogging of EGR passages in the intake manifold, or clogging of the EGR cooler. Is this applicable to the Gen 1? I realize that the COPs, plugs, and fuel injectors should be verified good before heading down that rabbit hole, but I'm just curious whether the EGR clogging has ever been documented in the Gen 1's. My car has lots of miles, so egr clogging definitely seems like it could be possible/likely.