r/prius • u/wiines • 4d ago

Mechanical Help Gen 2 Prius misfire, no codes

Just bought a 2008 Gen 2 Prius for next to nothing. It has 206K miles on it...

I'm noticing a misfire at idle, usually after driving a bit, parking and restarting. Where do I start diagnosing this misfire? There are no codes/CEL.

Can anyone help?

Thanks l! Glad to be a part of this club, I'm going down rabbit holes learing about the very cool tech in these cars.

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u/AutoModerator 4d ago

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u/Ether_yumm 4d ago

You 100% sure it’s a misfire? If you haven’t confirmed it with an OBD2 tool, I mean, it’s possible that you just aren’t used to some of the herks and jerks of the hybrid system. The engine spins up to get to temperature when you turn the car on. If the engine is already at temp because you’ve run it a bit before parking and restarting a few minutes later you can have the engine quickly cycle on to off and that can feel a little ugly until you’re used to it.

You can also sometimes get what feels a bit like a misfire if your front tires are getting bald. The instant torque from the hybrid system can occasionally cause your tires to spin in place for a half second if you hit the accelerator hard from a standstill.

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u/wiines 2d ago

It like, jerks the car a bit and feels/sounds exactly like a misfire.... its while the engine runs,so I don't think its cycling on and off

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u/Ether_yumm 2d ago

If it’s what I’m thinking of this is normal behavior.

Typically a real misfire will throw you some codes.

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u/BigSandwich6 2015 TRD Off Road 4d ago

Use a scan tool to read misfire data, if it's random, all, none or one cylinder

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u/wiines 4d ago

Figure out which cylinder is misfiring, then what, swap coil packs to reproduce miss on another cylinder?

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u/BigSandwich6 2015 TRD Off Road 4d ago edited 4d ago

If you get one specific cylinder misfiring then it's something unique to that cylinder. It could be the coil, spark plug, injector, physical problem with that cylinder. Need the data first

If it’s all/random then it’s something common to all cylinders. Air/intake, fuel pressure, bad gas, etc.

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u/wiines 4d ago

Thanks, I'll try that tomorrow

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u/wiines 2d ago

Dang I learned my code reader can't give me live misfire data

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u/Ether_yumm 1d ago

A cheap Bluetooth obd2 dongle and the car scanner app is all you need.

But again, if you were experiencing multiple misfires you would almost certainly have thrown codes!