2010 PRIUS IV - engine/transmission - headache/migraine

Might be the solid/hydraulic lifters?

 

Great article your posts are all clear, detailed and well written.
In short hand I will say thank you x 50.
I think I have your damper condition based upon your arguments that hard acceleration stopped the noise, highway driving stopped the noise and neutral stopped the noise. I have already done the EGR system and plugs and I have no coolant leak. I must find a good garage in the Montreal area to first confirm my head gasket is good and that they are able to do the job. Hopefully the labor will be close to what you paid.

 

Nope though my symptoms were identical to yours -- based on your descriptions -- my problem turned out to be nothing more than a loose middle heat shield. I guess I was lucky. As well, I have become pretty knowledgeable on the damper replacement if I ever need to do it.

 

These symptoms sound almost exactly like what my 2010 does.

I've had a lot of issues with clogged EGR, clogged catalytic converters, bad plugs, even a case where my catch can unscrewed itself, but now, after finally being "code free" I still get this weird "clatter" sometimes when I stop, and this odd "surging" sometimes when I let off the throttle.

Lucky for me however, my decision is easy - because my car burns approximately a quart of oil every tank, I'm not going to bother with the damper replacement, but at least I have some idea what is causing it.

I'll probably still clean my throttle body and traction battery fan vent, but I doubt those will make any difference.

On the upside, the new plugs have greatly improved gas mileage. Gonna hit my first 480 mile tank!