severe knocking noise, please help

[pimpone60]

i just bought a 01 prius with 225,000 miles...the story is, they were driving down the interstate and it started this knocking noise...said the local toyota dealership said the gas engine is bad...i'm not sure it is...i start it and it starts good..then after a few seconds, all heck breaks loose...it starts this extremely loud knocking/rattling....seem to me that its coming from the trans area more than the engine area...the gas engine is shaking some like its got a miss and the scanner shows 2 cylinders misfiring..i'm almost sure its not the gas engine thats bad...whats weird is when your sitting in the car and its knocking like crazy, you take it out of park and the noise goes away..it takes reverse/drive fine and pulls in both of them...put it back up in park and the noise starts again...you can feel the knocking in the floor and the gear shifter...sort of a pulsating in the shifter....info center says everything is charging and working...if i had a way to rev the gas engine in neutral it might rule out the gas engine being bad....i'm new to the prius but i have been around cars my whole life...it almost sounds like the "clutch" between the engine/trans has come apart..or some gears stripped in the trans...call me if you want 870-476-0115

[Flying White Dutchman]

the scanner shows 2 cylinders misfiring
and you think its nog the engine

[pimpone60]

just because it shows a misfire does not mean the cylinder is dead...could just be a coil...still doesn't explain why it stops the noise when i take it out of park

[Flying White Dutchman]

start adressing the misfire and see what happens

[Patrick Wong]

Since you've retrieved DTC that shows two cylinders are misfiring, it would seem reasonable to inspect the spark plugs, igniters, and fuel injectors for those two cylinders (cyl 1 is on the RH or passenger-side of the car) and see if you find any discrepancies.

When the car is in Park, you can rev up the engine.

You can also put the car in "inspection mode" to force the gasoline engine to run at all times. When the car is IG-ON (not READY) and the gearshift is in P, fully depress the accelerator pedal two times. Then shift to N and fully depress the accelerator pedal 2x. Then shift to P and fully depress the accelerator pedal 2x.

Then press on the brake pedal and make the Prius READY. You will see the hybrid vehicle icon appear on the MFD and the gasoline engine will run continuously. Do not drive the car in this condition as the traction control is disengaged.

Also note that at low forward speeds when you are in D, and at any speed when in R, MG2 is providing power to move the car (and the gasoline engine is not on).

For your sake I hope that the engine is bad and the transaxle is good, because it will cost much more to replace the transaxle than to replace the engine.

[pimpone60]

which cylinders are 1 and 3? its almost the same cost on car-part.com for the engine or the trans/electric motor...this is the weirdest thing i have ever seen...when you start it cold, in park, it starts fine and runs quiet for alittle while...then its like you flip a switch and starts knocking...when you put it in rev,neutral,or drive, it stops the noise....shift it back into park and it starts it again...i'm almost positive(if thats worth anything) that the gas engine is good...i just don't want to buy a junkyard trans and it need the electric motor instead....another thing....i've been told not to let my mechanic change the motor or trans due to the high voltage situation....will he be ok if i disconnect the main battery(how do i do that) they are not dummies and have changed plenty of motors and trans for me but never a hybrid

[pimpone60]

i haven't tried the inspection mode but it won't rev up in park right now....do i have to put it in inspection mode to rev the motor in park?

[galaxee]

get a stethoscope and pinpoint the source of the noise, instead of guessing. when our es250 engine ate a rod bearing, that thing had a bottom end racket you wouldn't believe. will help you figure out what's up.

and clear up those misfires first, that's just illogical to ignore.

[pimpone60]

i'm gonna fix the misfires tomorrow and do the inspection mode test

[Swanny]

I'm wondering if the problem isn't related to the VVT system. I would get those codes read and see if any are related to that. Perhaps the camshaft/valves get out of whack because a valve timing sensor isn't working. Who knows. This will give you a sampling of what VVT problems entail - OBD-II Trouble Code: P0010 "A" Camshaft Position Actuator Circuit (Bank 1)

First thing is to get the exact codes read (P0XXX or P1XXX format). You can look up the codes here - OBD-II Check Engine Light Trouble Codes and post back with them. I know you said there were 2 misfire codes but there may be more codes or new codes. Always fix the first codes first (the first ones that show up on the code reader).