Death Rattle... clean manifold & EGR, new plugs, no change

Checking coolant for exhaust is a good idea. I have not done this, but there is absolutely no sign of
white smoke
coolant loss
coolant in oil
oil in coolant
(edit) or any sort of froth in the coolant

Also, engine purrs like a kitten in maintenance mode (no load idle) and runs great at high load.

Trans fluid was changed at 100k miles, probably not before (I bought at 98K). Genuine Toyota W/S as called for by owner's manual.

 

I understand the mechanical design of the transmission.

I agree that the "chugging" is roughly speaking engine rotation frequency. I get that this sounds like a head gasket -- because a blown HG is one way to get a big torsional excitation going, which is what we see here. But for reasons already stated, I don't think a blown HG is what is causing -my- big torsional excitation.

Now this is a walk on the wild side, but... I think there's a way to do a fuel cut in TS one cylinder at a time. Not sure if you can do in ready mode or just maintenance mode. If it can be done in ready mode, then would this be a <safe> way to confirm or refute misfiring? Obviously, if I fuel cut #1 and nothing changes, that would be a pretty solid clue that #1 is misfiring. And vice versa.

back to MG1... is there a way to see what the hybrid system is commanding for torque on MG1, and would it show me an instability (at e.g. 16 - 20 cycles per sec) if it existed? Various comments have been made over the years (and earlier in this thread) about the need for the hybrid system to synch nicely with the ICE... but I don't know how to dig into this further.

 

Thanks.... that was a great reply. So you are still going with "misfire".

Alright. What is a/the misfire scenario might I be looking for? Again -- runs perfect in maintenance mode (no load) and at full throttle.

 

This car has been on synthetic since new. In it now is 5w-30 Pennzoil Platinum, last changed about 1500 miles ago. Previous oil changes I've done were 0w-20, either Pennzoil Platinum or Mobil 1 AFE, I'd have to check. Change to 5w-30 was mostly for convenience (I use in other vehicles). I fill to the full mark on the dip stick and oil consumption is nil. There was -maybe- 5ml of oil in the bottom of the IM when I cleaned things out. PCV valve only a little dirty, still rattled, I changed anyway when things were apart, replaced with Toyota OEM.

I sent an email with link to video to a toyota "specialist" here in NH. I hope they reply, I need some new eyes, brain cells and probably equipment on this job.

 

If what's going on here is LSPI... holy sh1t. Is there any evidence that this is a thing in 3rd gen Prii?

 

Thinking about this for a minute, I'd bet a lot of money (about the cost of a head gasket job, for instance) that what I'm seeing isn't LSPI. It's too regular. And there isn't a hint of the high frequency ringing that is the telltale for end gas detonation (what everyone outside the Prius community calls "knocking") which I'm about 90% certain would be an inevitable result of LSPI.

 

In Techstream, there is a Knock Correction Learn Value, that in my case is 21 degrees. Is this typical? That's a mighty big number....

(edit) TSM says normal is 0 - 22 deg.

 

Dropped car off with local Obi-Wan. On way over, ears and butt dyno say it's misfiring at low/mid power, but still fine at idle and high power.

 

Obi-Wan took a look, says it's the transmission damper that's making the most horrible noise from the transaxle area (I agree). In his opinion, the engine is running fine, "it is not misfiring at all". Hmmmmm. So he agrees with the ECU (no codes). That's where I started out, but at this point I'm much less certain. Something is setting this cascade of torsional oscillations off (and keeping it going). When driving the car at low/mod throttle, HSI indicator on the right side but not into the "pwr" region, there is a sensation of power loss at times.

Sheesh. Okay, well I can yank the plugs, do a leak down test, endoscope the cylinders, that's all pretty easy, but the expected result is "no problems".

 

Interesting point, thanks. Knock sensor is listening for ringing after detonation, about 6KHz iirc. The ringing is a resonance in the high pressure gas inside the cylinder, not the ringing of metal parts. So, I need a bang sensor in addition to knock sensor . I actually have chassis ears, but in this case I don't really need them.

(edit) There is one knock control event in a log I recorded. That's interesting... but I don't think it's the main story. I'm going to go for a ride and log some more.

 

Did all my errands today with the Prius... 50 miles, 61+ mpg recorded for the trip on the dash display. Don't see how that happens with an ICE that is wounded and misfiring. Rattles disappear instantly if you floor it.

Obi-Wan clearly not salivating for this job (I don't blame him, lol, Prius isn't really his thing).

Meanwhile, another shop I engaged via email has replied and also thinks (based on that video and other detail I provided) that the damper is the main problem.

I presume the repair begins with step 1) remove engine and transaxle. Can anyone hazard a guess at the time / labor here?

 

You'd think that enough misfiring to fail a damper would have thrown a DTC (?).

As previously mentioned, I'll have a look inside the cylinders and some compression & leak down results, plus some professional eyeballs on the job before we commit to serious repairs.