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

No warning lights? No misfire codes, P03XX?

It "sounds" like head gasket failure; try a leak-down test?

 

It would be surprising if this does end up to be a bad head gasket. As this car seems to be cared for with minimal oil burning, EGR seemed clean.

But there's also the water pump, if that failed or working intermittently, car can get hot and result in a head gasket failure. My mechanic bought a 300k miles car that had similar symptoms, rattling at low rpm, drives fine at high speed/rpm. Ended up being a bad head gasket.

 

I changed out my water pump at 135k miles on my 2010. As a preventive measure since it's over 10 years old.

I suspect if you did have a head gasket failure, it's at a very early stage. But not having any misfire codes and rattling like that, is very puzzling.

 

Things, ie EGR, may get stuck closed, they may get stuck open, or maybe even somewhere in between. I would venture yours may be stuck open, hence the suggestion to close it and see if the problem disappears.

REVVL V+ 5G ?

 

If the valve sticks open, the engine's normal idle is likely to be poor.

If you have Techstream, you can use the active tests to send the valve to different step positions and note the effect on idle quality and manifold pressure. This is an easy way to confirm the valve moves without breaking out the wrenches.

 

EGR diagnostics from Repair Manual attached:

 

There was a TSB from Toyota that addressed the EGR valve, it has an extended coverage for 10 years. Your car is slightly over that time frame for it to be covered by Toyota.

If I recall correctly, the language on that TSB suggests this would be a problem on cold starts, where the engine would rattle. And there would be a code that's thrown. I think your experience is not just on cold starts, it happened when it's nicely warmed up.

 

I did the flash DIY. But left old EGR and intake manifold. Requires a more expensive VCI, (mine's from Drew Technologies), and the $65 subscription level. Not too hard, just getting the setup right (to connect to their server properly) wasn't intuitive...

REVVL V+ 5G ?

 

@JC91006 I updated my post #19 with the first two pages of each for reference which models are covered, warranty details, and part #s, as of last fall...

REVVL V+ 5G ?

 

Or if you don't have Techstream but you have an OBD reader you can do an empirical test like me.
As you can see, idle, EGR valve closed MAP sensor shows some vacuum and MAF sensor almost nothing.
On the road, EGR valve open and MAP sensor close to atmospheric pressure and MAF sensor shows some airflow.
So it seems that EGR valve is working fine.
Or at least I hope so.

 

Can't forget, though, that "on the road" there are other reasons for the MAP to be close to atmospheric and for the MAF sensor to show some airflow. Like, the throttle being open, because you're on the road.

That's why it is hard to tease out any EGR effect from MAP and MAF values while driving. (The ECM's own EGR monitor routine does that, but does it at very specific times while driving, and does it a very specific way.)

A MAF reading doesn't reflect EGR flow anyway; it enters downstream of the sensor.

 

I know, that's why I said an empirical test.
I'll try next time to do another test on the road. Keep a steady acceleration with EGR valve open and maybe at some point it will close itself and then I'll watch changing in MAF/MAP sensors.
But I must work with my wife for that because she's the driver.

 

The difference between whether a test is workable or not isn't exactly the same as whether it's empirical or not.

Most of the useful stuff learned over the ages has been thanks to workable empirical tests.