Judder on cold start and idle

Discussion in 'Gen 2 Prius Main Forum' started by Has Raf, Mar 25, 2025.

  1. Has Raf

    Has Raf Member

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    Having an issue where my 2nd gen judders on idle and cold starts. Only when the engine is running. It’s an odd judder. The car judders every 2nd sec or so. I think it’s doing it whilst driving too. Misfire? I’m not so ‘clued-up’ on misfire symptoms. It’s just been to Toyota for a 100k service. They didn’t mention anything re misfire or engine issues etc. Thanks in advance.
     
  2. Tombukt2

    Tombukt2 Senior Member

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    Do you have any lights on on the dash that's the first thing? Usually when misfires are happening the check engine light and a lot of these generation tools will fire off like a disco ball it'll be on your dashboard just flickering away like crazy as long as the missing is happening no matter if it's one or multiple cylinders so do you have any of that going on? And then the next thing to do is run the car to temperature during the day afternoon whatever Park the car where you can take the plugs out right in front of your garage door whatever let it sit all night. Then in the morning take the plugs out use your magnifying glasses or a jewelers glass so look at the tips of the plugs the ones that you see little ter miny water droplets on. Are the problem take your finger touch the water droplets touch it to your tongue You should taste glycol take the cap off your antifreeze bottle and just take a sniff and now you're sniffing what you just tasted see how that works so wherever you got that taste or smell or water droplets from is water seeping in that given area doesn't have to be a lot man It can take days for the water to go down and for you to see it as an overheat or something I've got an '09 that's doing this right now and I can drive it almost a long time until it gets to the point where it'll get hot enough for it to tell me
     
  3. Has Raf

    Has Raf Member

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    No error lights, not a single one.
     
  4. Tombukt2

    Tombukt2 Senior Member

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    Usually when you're misfiring like that you should get something going on so maybe you're capable scanner needs to be looking at the freeze frame to see if you can see anything in the freeze frame data or you're not missing I mean I can't imagine sounds like you are by your description of what's going on and moving plugs and coils around I don't think is really ever worked for me because usually when this has happened it's usually been water entering in to one of the cylinders by a leak.
     
  5. Has Raf

    Has Raf Member

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    I’ll get the Autel on it in the morning. Could it be anything else other than a misfire? Would a worn aux belt give similar symptoms? I thought maybe worn engine mounts, but can’t see any give or movement in them. Toyota said the exhaust gasket is worn which is causing a slight blow (rear section where it connects with the bolts with the springs). The car is louder from that area to be honest. Could a worn exhaust gasket cause a judder?
     
  6. dolj

    dolj Senior Member

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    Leaking from the exhaust gasket will cause problems with the ability of the ECM to set the mixture.

    I hope it is not indicative of a blocked catalytic converter.
     
  7. Has Raf

    Has Raf Member

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    Even from the gasket at the rear of the exhaust, before the back box?
     
  8. Tombukt2

    Tombukt2 Senior Member

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    Way at cat back. Connection I would think not. But up at manifold downpipe different story possibly . The exhaust shop can tell ya quickly just feeling sir stepping on gas for the most part .most meccies could place hand at pipe whilst assistant revs vehicle and pretty much know . Cat clogging is a generally slow process.
     
  9. dolj

    dolj Senior Member

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    No, not if that is after the O2 sensor. I thought you were talking about the doughnut gasket on the manifold.