I have a 2007 Toyota Prius touring @ 234000 it's having issues and I personally don't understand what going on. When you start it up in the morning mostly it makes this rattling knocking sound if I didn't know any better it sound like a rod knock. Once it warms up it seems fine. I sent my borescope down into the cylinders they look normal for the mileage there were no shiny pistons. It does get random misfire codes but it seems to only be in the morning cold start and we're talking small count numbers. Facts: New plugs... made world of difference New water pump New coils Any prius master techs want to chime in?
Any warning lights/error codes? Does the exhaust smell different? Signs of leakage around headgasket? At what rate is it burning oil? Did you let oil level get really low at any point?
P0302 Couldn't give you an honest answer on a gas exhaust smell, I would have to say no. There are no signs of leakage around headgasket. Have not had vehicle long enough to say how much oil it is burning if any. Not aware of this either.
I've run into similar symptoms from a mom who let her teenage driver loose with her Prius... Was suspicious about possible aggressive driving combined with not adding oil led to these same symptoms. Evidently the lack of oil can often first show up as a misfire error code due to excessive crankshaft vibration. Once I changed the oil and the plugs it took a while for things to settle down and stop throwing misfire error codes. But car has been running without issue for more than 6 months. So if you're interested, it might be worth buying an oil pan gasket and dropping the oil pan and seeing if you have any metal dust in it... Or just do an oil change.
I will do an oil change today, just for peace of mind. I have a funny feeling that is coming from the Synergy Drive area possibly transaxle maybe MG1 or MG2 has a bad bearing.
I can't imagine how a bad bearing in a planetary gear based transmission is going to cause the engine to run rough... Make sure you measure how much oil you remove, as well as smell it. If it's a blown headgasket it could have radiator fluid in it. And you do know that it's perfectly normal for Gen2 and Gen3 to run rough at start of cold startup right?
It's the noise it makes that scares me more then the fact that it runs rough and that continues to give me a misfire code. Just finished the oil change and a ATF fluid change nothing really struck me out of the normal. And still getting that awful rattle/knock.
Yeah... Now that you've done the fluid changes I'd suggest you buy an intake manifold gasket and do a super thorough cleaning and inspection of intake system to see if you find anything out of the ordinary. Most people just do a throttle body cleaning by stuff rags down the intake and using lots of carb cleaner, but a couple weeks ago a guy got on here and said he found it hardly took much additional time to remove the manifold for a more thorough cleaning. And once all that checks out, I'd do a compression on the cylinders to make sure all those numbers check out. And assuming you already tried, but disconnecting the 12v reboots the system and is essential to doing after tune ups and clean outs.
Misfires are not caused only by spark plugs.... most common..... spark plugs coils fuel injectors loss of compression really bad air-fuel ratio/mixture excess carbon build up Cold Start misfires? see above plus it's sometimes caused by the MAF, among other theories. What about minor head gasket issues possibly putting a bit of fluid in that cylinder? Google cold start misfires. It'll give you plenty of paths to travel.
I took a stethoscope the noise was the loudest near the axle output on the transaxle wasn't as loud in the oil pan or near the head of the engine it was the most prominent near the transaxle lower area.
Update: Intake was fairly clean but the injectors were very dirty. So I cleaned everything up in the ultrasonic cleaner. Misfires are gone and MPG is much better from 29 to 40+ Still have the same noise though.
Random misfires are indicative of possible blown bottom end of motor. Seen many of those on this site. The vibration from the knocking distorts the fg/pg pulses from the cam/crank sensors and the engine ecm see's it as multiple misfires. Did you just buy the car? High mileage G2's usually suffer from some level of oil loss from worn piston rings. Many people become aware of the oil loss problem when the check engine light comes on from no oil in the engine. Usually too late. A good one of those will cause bearing damage in the engine. Top 2 reasons G2's are sold or traded in on the spot is bad hybrid battery or engine eats alot of oil or the new #3 the brake actuator has failed and dealer hits them with a $3000 bill. Traded in on the spot off it goes to auction. No one checks there oil anymore especially on this car and especially if the oil changes are done at the dealer.
So far good, noise was the crank being off balanced because the injector(s) wasn't working good enough.
