Techstream EGR Valve Blockage Data

Exactly. Prevent Maint is cheaper than Rehab maint.

the $1450 included:
Full EGR Clean
Oil Change
Inverter and Engine coolant flush
Water Pump Replacement
Spark Plugs
and a free engine bay cleaning. Shes purty under there now.

 

OUCH! That's a lot of money!

 

Reasonable?

 

Well actually....
Don't we all see a big jump in fuel economy with the warm spring weather?
I know I do, but I don't keep accurate records to nail an exact number. Sometimes it may be ~10%.

Your list of items done does sound like a reasonable price!

All you have to do now is continue with this Ol'Gen3 to see if the head gasket hangs in there for more than 100-150k miles.

 

I appreciate I'm late to the party, haven't read much of this thread, have questions:

The EGR valve degree of open is monitored by the car's computers. It has parameters, say throttle position, rpm and load condition, for when it can open the EGR valve?

How about how much and/or long to open it? Does it monitor rpm drop for example? If there's clogging of the EGR capillary passages in the intake manifold, reducing the results of a certain degree of opening of the valve, does it then open the valve more or longer?

I'm wondering: would a clogging EGR system mean the EGR valve will be opening more or longer, be prone to wear out sooner?

 

Your first comment in this thread was on May 5, 2019.

The ECM doesn't really know how far open the valve is; there's no sensor on the valve. It just has a stepper motor, something like 111 steps from fully closed to fully open.

The ECM can get to where it thinks the valve is closed, by sending it 111 or more steps in the 'close' direction and assuming it must have got there. It can then get to where it thinks the valve is n steps open, by starting there and sending n steps in the 'open' direction. If the valve gets sticky and doesn't move the same number of steps that were sent, the ECM has no direct knowledge of that.

The only feedback the ECM gets on what the valve is doing comes from the effect on the MAP sensor reading.

I'd say the valve is built robustly enough I wouldn't worry much about it wearing out no matter how often it opens and closes. The ailments that it does seem to be prone to are (1) melting a rut through the ski jump, or (2) getting caked up and sticking.

 

Do you really think, it is sticking, because it is "caked up"?

It is absolutely possible, we had here some reports, where the plunger was not moving freely.

Wouldn't it be possible, that it is sticking, while the stopper gets caught in the completely or partially melted rut (apart from opening the valve less than the ECU commands, due to the steps needed to get over the rut itself).

As my old valve was replaced, Toyota mechanics said "it was sticking".
After disassembling the valve, I found the ski jump fully melted through and the valve plunger actually moving free, even, if reasonably covered with carbon residue.

Mat

 

I suppose a partial rut could be one cause of sticking behavior. I consider any sign of rut to be a sufficient reason for replacing the valve in any case; I've never felt a need to settle the question of whether it's the only reason the valve could stick.

I had a used valve apart where I didn't think the pintle moved very smoothly.

 

Yes a factory egr valve can wear out.

 

What part of it did you find to be worn, and how?

 

Interesting video. I've watched a lot of Car Care Nut's videos over the last few years and I generally trust what he says. I have picked up, though, that English might not be his first language and sometimes he seems to use the wrong word or phrasing, changing the meaning of what he seems to try to be saying. In this case, I think he was meaning to say that there's no point in fully cleaning the EGR cooler as it will get dirty again. I think he would agree that if it was actually clogged, it should be replaced. He essentially said as much about focusing on obstructions. He also blasted it out with compressed air...which shows it was not completely clogged.

He seems to be implying the same thing I've been feeling these past few years, which is that the thing we all need to focus on is NOT maximizing EGR flow from start to end, but rather on creating consistent/predictable flow through the valve that is balanced across the manifold ports.

At the end of the video he talks about installing an update via TechStream. Has anyone done this?

 

Toyota dealers do it all the time. They are running Techstream over the ~ $500 dongle from Opus IVS that Toyota officially supports, and they also have a long list of prep steps, putting a supplemental power supply on the car's 12-volt battery and disabling some of the car's heavier electrical loads, all to try to minimize the chance of an electrical fluctuation leaving the car bricked mid-update.

It's not something I personally would want to do with Techstream at home, using one of the cheaper dongles not officially tested by Toyota. When I learn of an update that I would like applied, I generally just go to the dealer and pay them the hour of shop time to do it. If anything goes worngg it's their look-out.

The particular firmware version they recommend after changing the EGR valve is the same version they also recommend in a different TSB that involves changing the intake manifold for a different issue. So depending on which work you are doing, you can end up with this firmware and the old EGR valve, or with this firmware and the old manifold, and so I doubt there is anything in the update that's intrinsically tailored to a particular version of either part. I think the later version simply has some updates they also think will be useful if you have been having either of those issues.

I've asked them to apply the update for me even though I still have the old manifold and the old EGR valve. My reasoning was that it might also contain the updated water pump control algorithm they released in Europe in response to head gasket issues. I have no way of knowing if it really does or not, as the firmware is closed-source.

The only difference I think I've noticed with the firmware update is a slightly increased idle RPM on cold start, until the coolant temperature hits 30℃. That's the kind of easy change you might make to smooth things out on cold starts.

 

Yes several of us have had the ecm updated. I also installed the revised egr valve.

Newer EGR Valve Kit. 04004-58137 includes 25620-37120

I agree egrs are not causing head gasket leaks as does Toyota, their Master mechanics and other professionals. If it codes, fix it.

These days the hacked Techstream everyone seems to use won’t work for updates. A completely new version is required.

 

Cheers. Do you happen to know the TSB number associated with this update? Or I wonder if I could just ask a dealer to give me all the updates since 2012...
I'm not experiencing any issues (except when I forget to empty the stupid catch can that I regret installing) but thinking proactively.

 

T-SB-0103-12 Rev2 is about an intake manifold change, if you're having P2111 and P0A0F after cold soaks,

T-SB-0027-16 is about an EGR valve change, if you're having P0401 or rattles after cold soaks.

If you flip to the "Calibration Information" table in either one, you can see which firmware version it recommends based on your car's model/year. You can see they recommend the same versions, so either one of them could be "the TSB number associated with this update".

 

Thanks! It's the same for both (2012 Prius in my case). Interestingly, the previous "calibration IDs" are 34734000, 34734100, 34734200 and 34734300. The latest in those TSBs is 34734400. I googled that number and get hits. When I google 34734500 nothing relevant returns. I wonder if those are comprehensive patches for the vehicle, or solely for these related issues. Either way, it seems 34734400 might be the last/latest.

 

Still, I would think it's cooling efficacy (it's colloquial namesake) is impaired by that blanket of carbon. When the car rolls off the factory floor, the cooler is shiney, bare stainless steel. I like to keep it that way.

Toyota's hoping the problem will blow away. Well it will, and maybe potential repeat customers as well, with their checkbooks.

 

Well, keeping the EGR cooler, itself, clean has little to do with the Chronic Head Gasket Failures, imho.

Another theory is the EGR gases precipitate out the carbon crud as they get cooler going through the long, thin, cool, Plastic Intake Manifold Passages and clog the small ports farthest from the source of this hot waste gas,,, namely cylinders 1 and 2.
And that is where the head gaskets seem to fail first, correct?

(I've seen some manufacturers wrap EGR plumbing lines in that high heat fiber and orange silicone rubber material just to keep the gases as Warm as possible so the crud doesn't condense in the lines.)

Or,,,
Could it be that the Head - Head Gasket - Block is just a pisspoor design? Maybe all the hot-cold cycles a hybrid engine experiences?

Example: I was working with a guy that, just yesterday, had his '17 Gen4 Prius start "shaking and has the Check Engine light on".
He dropped it off at his dealership. He bought it used with ?35k mi on it, BUT has taken it to the dealership for all its required maintenance. He's now at 205k mi.
I told him to get ready for the worse... Any guesses?? I was with him when the dealer called...

Dealer says, Blown Head Gasket. $4800, if you want new pistons and rings, $5800.

I suggested to him if the oil consumption is good and the problem just showed up this morning, skip the pistion/rings.

I'm aware of Gen4's having a "new and improved" EGR system. I haven't looked at Gen4's to see if the Ol'Head Gasket Failures are also a chronic thing.

What is an alternative to having the dealer do this work? Is there that mobile service company in the midwest, KC area?

Let's hope the Gen5 is a totally new engine...