Misfire detected- P0300 p0303 set

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by Megadeus, Mar 3, 2012.

  1. Megadeus

    Megadeus
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    I've been running around the forums and my reference manuals trying to nail this one. P0300 p0301 p0303 were set.
    2006 prius btw...

    I drove it around with my scan tool (snap on modis) watching the misfire histograms. I replaced the spark plugs and dried out the spark plug wells of any moisture because I had 'just' washed the car before the misfire happened. Much to my dismay, the misfire was still present and constant.

    I had a dead number 3 cylinder. I swapped coils with another and number 3 was still racking up misfires. So it wasn't a coil issue. I pulled out the #3 plug and put in a new one in case the replacement was a dud.

    No good. Still misfiring.

    I pulled out the number 3 ignition coil and inserted a known good plug. It was lighting off like a Chinese New Year, so it's definitely being commanded to fire.

    I poke n prod trying to find a wet connector, something loose, who knows what. Nothing jumps out at me.

    I performed an injector disable test.

    1,2, and 4 drop rpm's but 3 does nothing.

    It's been a LONG time since I've found a bad injector but I think tonight is a first. Call me wacky, but when cylinders 1,2, and 4 have a resistance of ~12.5 ohms with a bastard number 3 injector reading 14.5 KILO-ohms... makes ya wonder. I haven't found another thread on Priuschat of anyone coming to the same conclusion.

    If someone has, I'd like to read their story.

    At this point in time, I'm sourcing a replacement fuel injector.
     
  2. Baz2473

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    Megadeus, im having the exact same problem can i ask if the new fuel injector fixed your problem?
     
  3. MTL_hihy

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    If you see a code like that on a specific cylinder and it's not the coil or plug, 99% of the time you likely have a bad injector.
    You can try 2 bottles of seafoam in your gas tank first and see if that helps but if you still get a misfire then you'll need to replace it.
     
  4. valde3

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    If injector resistance is incorrect cleaning won’t fix it. You need new injector. This isn’t common problem so you can use used injectors just get new O-rings.
     
  5. Baz2473

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    I've just been out and tested the resistance on all four injectors and they are all around the 15 ohms region. Would this indicate that it's not the fuel injector which is causing the misfire in cylinder 3 when the vehicle is hot? Doesn't seem to do it when the vehicle is cold!
     
  6. Baz2473

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    I've just found a site for online workshop manuals and it states that the resistance on the four fuel injectors should be between 11.6 and 12.4. Seeing as mine are all around 15 is that a bad sign?

    Thank You to everyone who has helped so far, this forum is amazing!
     
  7. valde3

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    My Toyota workshop manual says they should be 13.45…14.15ohm. But you should first test your multi meter before coming to the conclusion that they are all bad. But then again if you get injectors from junk yard you might replace them all anyway.
     
  8. Mendel Leisk

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    Were you washing the car or the engine bay?
     
  9. Baz2473

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    Nope. First it was displaying an EGR code. Then the misfires started. I've fixed the EGR but am now left with misfire on cylinder 3.
    Only seems to happen once the engine has warmed up.
     
  10. Baz2473

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    Just thought I would point out that my Prius is a 2010 t-spirit with 230,000 miles on it.
     
  11. edthefox5

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    What kind of ohmmeter are you using? When you short the leads together on the ohmmeter what does it read?

    Ever run it low on oil? When the engine is running get under the car and listen for a knock or lower end bad sounds.
     
  12. valde3

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    Now I read this more carefully. So all your injectors show same resistance? It probably just your meters problem and cars problem is somewhere else.

    Have you tries swapping igniters around to see if misfiring cylinder changes? If yes its faulty igniter. If no then change plugs. If still no change try injector cleaner. If still no change, get back to here and we can give you more help.
     
  13. Baz2473

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    It's a SkyTronic 600.527.
    It reads 07.1 when I touch both leads together.
    It has ran low on oil loads of times. It seems to use about 2 litres of oil every 500 miles. Has done this for about a year now.

    I don't need to get under it. It's very loud upon first startup it sounds like there's a ratchet in the engine bouncing around but if I accelorate a bit it goes nice and quiet.
     
  14. Baz2473

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    They don't all show exactly the same. It ranges from 14.2 upto 15.1 across all four.

    I've swapped the ignition coils over and replaced the spark plugs but it's still only cylinder 3 that is misfiring.
     
  15. Baz2473

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    image.jpg Just noticed this on my dipstick!!!
     
  16. Mendel Leisk

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    Yeah, were you spraying water in the engine bay??
     
  17. Baz2473

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    No. No water anywhere near the engine bay.
    Does look like water in my oil though doesn't it.
    If I wipe it clean then re dip it, it then comes out looking like normal?
    I'm completely baffled. This car has had no problems at all up until now.
     
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  18. edthefox5

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    Again get under car and see if the bad sound its making is in the lower end. If so you have a main bearing failure and that's why its showing a misfire. It may have poor acceleration also as the knock sensor is pulling timing.

    Your loads of running low on oil blew the motor.
    Start looking for a new motor.
     
  19. edthefox5

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    Your o meter is not zero'ed out and already showing 7 ohms so deduct that from any resistance measurement.
     
  20. Baz2473

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    Ok. Tomorrow I'll get under it. I reckon you're rite. A friend of mine heard it today and said it sounds like my bottom end has gone.

    Gonna start looking around for a good deal on a new one. Quite like the idea of led headlights.

    Thank You for all your help people.