How many miles on your Gen 3 and what Repairs / Maintenance have you done?

How do you change that setting?how do you change that setting?

 

Thanks for the detailed explanation!
This self-testing routine makes sense. Having the throttle plate closed during this testing makes the incoming air a known quantity.
And thanks for the link to EGR Flow Score thread. I haven't read much of it yet, but hoping this is data that Torgue Pro, with the Prius PIDS, can show. All I have to do is get those pids loaded to my phone so Torquepro can use them.

Side note: I was helping a neighbor troubleshoot his Ram truck Eco diesel. It has an EGR cooler that looks very similar to the Prius. And it has a 'watercooled EGR valve'. This was just replaced under warranty. He get's 'Low Turbo Boost' codes intermittently.

Anyways,,, The stainless steel pipe from the EGR valve to the plastic intake manifold has a nomex like insulation on the outside. And there's a big piece of molded foam rubber that covers the cooler and valve.
I can see the wisdom of that. Keep the flow hot so it doesn't condense inside the pipe. The pipe exits with a simple tube that dumps the EGR into the center of this big plastic manifold.

So,, an upgrade for the Prius EGR system! Wrap that EGR valve-to-intake pipe in high temp insulation.
And spray foam the top of the intake manifold where the EGR passages are.
You can apply that foam and then cover it with a plastic bag and sort of form the outside to an even thickness.
Then peal the bag off after it has set hard.
I'm sure the particles will still condense on the passage surfaces, but this mod may slow down the build up....

What say you?

 

Don’t think that’s the inference; he’s just saying you don’t have to wait for it to get to that threshold where it throws the code?

 

Exactly; I was just saying you can look at the number now and then yourself, decide how low is your threshold for taking some action.

Monitor test results are a different OBD-II thing than data PIDs. I don't know whether Torque Pro groks them or not; you'd have to skim the instructions to see something about "mode 6" or monitor results or emissions monitors or the like. (Or skim that test results thread to see if anybody's already shown Torque Pro doing it.)

Insulating the pipe and spray-foaming the manifold would surely be counterintuitive to those here who attribute engine risks to the heat of the incoming gas. That doesn't mean it's wrong; definitely widens the universe of things to think about. I haven't really been sold on the "it's the heat" view in the past, and I don't know if I'm ready to jump on "keep it hot" either.

 

Right, this is the territory of the white lab coats standing in the dyno room.
It's all about controlling combustion temps and pressures in the end.
I definitely don't have an opinion on this subject.

But my reasoning for keeping the temps up from the EGR valve to intake port is to limit those nasty particles from condensing onto the passages so quickly.

Of course the EGR cooler has a job getting exhaust temps down to manageable temps.
That eco diesel had an EGT temp probe in the EGR valve. There are so many controls on a modern diesel to keep it clean.
Good ! I love how semi trucks and trains are not making black smoke and they are both so much quieter these days.

Thanks again for explaining needing to use Tech Stream and not Torquepro.
Is this EGR test something that has to done while driving with a mobile tech stream,
or is this test stored now in my Prius and I have to ask someone to read it for me?
How much might that cost?

 

The test gets done by the car all the time. The most recent result is what you will get when you ask for it with a scan tool.

OBD-II "Mode 6" emission monitor results are definitely a standard OBD-II thing and you are definitely not limited to Techstream for retrieving them. You can use any OBD-II scan tool, phone app, etc., at all, as long as it is capable of retrieving mode 6 monitor results.

If you skim through that EGR flow score thread, you will see many examples of different apps or scan tools being used to retrieve the data, not just Techstream by a long shot. I just don't happen to remember whether Torque Pro has that ability or not. My not remembering does not mean it doesn't.

 

My take is reduce the hydrocarbons going into the egr. Just like they did for gen4. Or don't have one at all like gen2.

Not much can be done short of keeping the engine pristine from day one other than installing a rebuilt gen3 engine with updated pistons and rings. The liquids buildup in the intake is not great either. Maybe an enterprising aftermarket source could design a modified intake with a liquid drainback to the crankcase. A solution other models use.

 

What about an oil catch can? Do you think that helps?
My '10 is getting great oil mileage so far with 125k miles. But I'm undecided about when and if to get into the EGR cleaning job.

So your '13 has 270k miles. What has it needed so far? Is its oil usage ok?

 

And periodically shovel out what’s accumulated anyways.

 

Sadly true. Someone with time on their hands, a few tools, a reliable car, a spare cooler, can o' brake brake cleaner, brushes and rags, could probably come out to your place, a mobile service, and find it worth their while, charging around $300~400. @jerrymildred will maybe chime in, on the time required to do this, once you iron out the kinks.

Come to think of it...

Too: @Raytheeagle had an exemplary approach, organizing/hosting EGR cleaning meet-ups, pooling tools, know-how.

It comes from the PCV circuit.

Until it isn't.

 

2015 Prius 4 has 40,803 miles bought new.
Trans fluid change, coolant drain and fill, Inverter drain and fill, cabin and air filters changed yearly, tires rotated yearly. Oil and filter changed (13 times) every 3,000 to 5,000 miles. Tires replaced at 31,978 miles. Cleaned hybrid cooling fan filter, maintenance done using age and or miles. I’m a bit of a maintenance nut!

 

I more or less concur with this recommendation, not so much with all the details/reasoning.

That's an oversimplified view. Regrettably, "people have been doing X for a long time" doesn't always mean X is a good thing to do, and sometimes it glosses over details that matter. One of those is the difference between EGR in a diesel and EGR in a spark-ignited gasoline engine. "EGR deletes" started in the diesel community, with EGR systems that helped NOx emissions but hurt performance and MPG. People would delete those to get their MPG back. In SI engines, EGR helps NOx emissions and helps MPG, so people with SI engines who do EGR deletes to imitate the cool thing their diesel friends did are kind of not paying enough attention.

Also, even in diesels, there's been a long time for the tech to advance and turn the original MPG hit into a wash or even a win, so even diesel owners doing deletes in recent diesel engines might also not be paying attention.

In this engine, EGR allows the spark timing to be advanced beyond what would be safe otherwise. The car does monitor the EGR flow, and will set P0401 if it ever gets really low, and as soon as it sets P0401, it automatically limits the spark timing to protect the engine. But it has to get really low to set that code: as we've been seeing, a flow reading of 21 or 22 kPa is typical for freshly cleaned (units of pressure because the MAP sensor is used to detect it), and the 'min' passing threshold is down around 1 kPa.

Some people might prefer to watch that flow score and clean the system when it is down to some higher value (I cleaned mine around 10 kPa, for example).

Anyway, because the car keeps track of that nice flow measurement you can check any time, that gives you an easy way to decide when you want to tackle a larger cleaning job.

Meanwhile, it still makes sense to do the manifold as a routine matter, because (a) as you mentioned, it's a lot easier, and (b) the car's overall flow measurement can't detect flow differences between the manifold's four EGR passages.

When you have the manifold off, those four tiny passages are key things to look at. If they clog up differently (which is typical), the car can still produce the right overall EGR flow, but it happens by sending too much to the less-clogged cylinders, and too little to the more-clogged ones. That can lead to misfires in the cylinders getting too much, and detonation risk in the ones getting too little, and the car doesn't know to back off the spark timing, because the overall flow looks ok.

 

Very likely not. Did you ever get the insufficient EGR flow code? P0401?

 

I never got any codes so maybe it wasn’t that blocked. It sure looked like it though.and I am still glad I did it. I agree with you Mendel I don’t think the dealer did any EGR cleaning.

 

I agree almost 100%. It would be ideal if someone cracked the car's control logic and provided a tune for an egr delete. I would be the first inline. I do concur with Mendel that a significant amount of the intake liquids come from the pcv accelerated by low tension rings, oil burning and overfilling of the oil.

When you pause for a moment on this whole idea of a gen3 somehow "needing" to last past 200,000, it seems rather silly. Only the pandemic was capable of extending the life of many of them. The gen2 has a much better chance of becoming a longterm collectible, only because they encouraged the mass market to accept electrification.

 

Is there a pid to use more EGR? Anybody tried it to see if there's some improvement in fuel eco? Who writes them anyway?

 

OK, I paused and I still don't know what you mean...
I've had a Gen3 Level 5 with ATP and it was a great car!, until the head gasket started going bad at 240k miles.
Your idea is to drive it to the crusher one last time and 'put it down'?
Even though that's the only problem?
Sounds wasteful...and 'silly' to me.

 

I would agree with this. On the other hand, though, if you wait till there's a P0401, that cooler is going to be pretty packed and a lot harder to clean. I usually do the cleaning where I work. We do them in batches. Some of them are a real struggle to get cleaned. At the other end of the spectrum are ones where I'm tempted to just put them in the "clean" box without doing anything. Out of a batch of a dozen coolers, I'll get 2-3 really bad ones, possibly one nearly pristine one (usually not), and the rest are in between.

 

Like a lot of things in nature, this is likely one of the things where there is a right amount, and the fuel eco curve is descending on either side of that point. Learning where that point is and programming it into the ECM would have been part of the engineers' job description, so it would be just as weird to see much benefit from "hey let's increase the amount" as to see a benefit from "hey let's decrease it".