One more time on the EGR cleaning. Magic number of miles 'til failure?

I haven't seen a critical number. I started having issues at 145k miles. I've read about others where issues arose at 57k and over 200k. Lots of variables go into how soon the system will fail. Provided you have the requisite tools and are willing to get it done in one shot, it shouldn't take more than 5 hours. If I were you though, I would wait for the spring. Lots of variables in car repair no matter how prepared or good you are. Then there are these sudden weather changes in today's climate. In addition to sudden changes to life's needs.

Spend the time in between studying up. I have a thread posted documenting all the stumbles I made along the way (like not catching a gasket and waiting a week for a new part to arrive) if it helps you out any.

 

I've followed the topic from a distance. In a nutshell it doesn't seem like the odometer is a very useful tool in deciding when to de-clog an EGR system.

Member @ChapmanF has invested some time and energy on a more direct method: asking the car's ECU to report the EGR valve position, keeping notes and comparing over time.

If I understand the theory correctly, a gradually clogging system will cause the ECU to request an ever-wider opening of the EGR valve to increase flow. As the blockage gets worse, the valve is held wide open and the computer can no longer compensate.

Good luck!

 

I don't think you can quite ask the ECU for exactly what Leadfoot is saying there ("say, what EGR position are you using in normal ops?"). The things you can ask are closely related though:

You can ask it, "say, what was the score for the last EGR self test you ran?" The ECU sneaks in regular tests while you are driving, at times when you're decelerating and no fuel is being used. It will open the valve a certain amount and look for how much the intake manifold pressure changes (there's a sensor). The more the pressure changes, the better the score. The number is the change in pressure. It's often shown in kilopascals (kPa), though that is up to the scan tool. In kPa, a freshly-cleaned system seems to be around 20 or 21. Mine was around 10 point something this summer before I cleaned it.

If your scan tool shows you psi, 21 kPa is around 3 psi. (One member used a more obscure phone app that shows the numbers in kPa but labels them psi, which gives you nonsensical pressures, but if you're using that app you can just say "oh, haha, that's really kPa isn't it.")

The other thing you can ask the ECU to do is the active test; just start the engine and run it at idle, and you can manually tell the ECU to open the valve step by step. The valve has 110 steps to full open. At idle, usually by step 14 or so you'll notice the idle getting bad, and it will seem likely to stall out by 17 or 18 or so. If things are clogged, you might get further open than that before you notice the same effects.

The active test was my first idea, which might be what Leadfoot remembered, but only because I hadn't discovered that simpler mode-6 test yet.

The active test did prove useful in catching one much more unusual problem, where an Australian driver had the valve melt a path through its internal stop, during a very hot drive on a very hot (40 ℃) day. That meant the valve could go a bunch of steps past "closed" when it closed, and that showed up with the active test because you needed a bunch of extra steps of "open" before it was even open at all.



But that's an unusual problem, unless maybe you make very long hot drives on hot days in Australia.

One thing to remember: both of the above tests give you information on the overall EGR flow rate. There is one valve, one sensor, and you get one test result for the whole shooting match.

But in the intake manifold, the EGR path splits into four, and those can clog, and if they clog up differently, the ECU's tests of overall flow won't catch it. The engine ends up with some cylinders running a too-diluted charge and others with a charge not diluted enough, and when I think about the possibility of engine damage, that situation strikes me as more risky than just overall flow degradation that the ECU can detect.

The good news is that the intake manifold by itself is really quick to just take off and inspect for clogging of those small passages. The rest of the EGR system, by contrast, is a job you endurance-train for.

 

I'd recommend to clean the EGR components (including intake manifold) at the same miles interval as engine coolant change, ie: 100K miles, then 50K miles thereafter.

To get some idea of the condition (though you don't really know till you''ve got it all off), it's relatively easy to remove/inspect just the pipe between EGR valve and intake manifold, as explained in the this @NutzAboutBolts video:

 

I would clean the egr cooler, intake and valve as normal preventative maintenance now. Especially if you can diy and have a weekend to spare for the first try.

There is no doubt the egr system and intake will be thick with difficult to remove carbon and gunk. The intake manifold will have a soupy oil accumulation and the small egr passages may be gunked up.

There is some doubt outside of Priuschat that egr clogging causes head gasket problems. Almost all Toyota mechanics will admit there is an epidemic of head gasket failures in gen3 engines. The miles at which they occur is trending down as the cars age.

It is a big job to restore the egr system to like new flowing condition, so most pros just replace the egr cooler and separate egr valve if the customer asks for preventive service. If the intake is clogged they replace it as well. As a result this service done by Toyota will be well over $1,000. The normal egr failure with high mileage is an egr that sticks open. This causes poor running a low speed and wide open throttle when the egr is normally closed. That failure mode is not common on Prii.

 

Get a Bluetooth ODBII reader if you don't already have one. I use this Bluetooth OBDII reader. I paid for Dr. Prius and use Car Scanner (which I believe is free). Both aps work great with that reader. Only problem with this reader is it is a little short and as a result is a little difficult remove. Invaluable for Prius ownership.

 

I did the job on my 2013 Prius v at 94K miles. I took a lot of pictures, and posted them on this thread:
My Major Surgery saga on my 2013 Prius V. | PriusChat

I have changed the oil every 5K miles since I bought it with 23k miles on it. The EGR cooler was moderately plugged up. I bought a spare used EGR cooler on eBay. I was able to compare blowing (by mouth) through the "Clean" and "Dirty" coolers. It was clear that there was an enormous amount of gunk in the dirty cooler. You could not see light through the "Dirty" cooler, but you could see with the clean cooler. The plugs showed no evidence of oil fouling.

IMHO, there are two things that are most important with respect to Head Gasket failure:

1) Changing the oil every 5K miles instead of the Toyota recommended 10k miles. At 94K, my plugs were clean, and I don't consume oil. I still don't consume oil at 104K.

2) There are four separate EGR Passages in the intake Manifold, going to each cylinder. They get clogged easily, but they don't get clogged evenly. The EGR performance test tests all four cylinders together, so if ONE EGR passage is clogged, that cylinder might not get any EGR gas, and yet you won't get the P0401 code indicating there is an EGR problem. That one cylinder will burn too hot, and will blow the head gasket. ​

My recommendation is to do the whole job if you can, but at a minimum ASAP (in order of importance):

1) Clean the Intake Manifold passages. This can be done easily in an afternoon. Buy a Toyota PCV valve ($10), and change it at the same time, while the IM is off the car. Consider installing an Oil Catch Can.
2) Start Changing your Oil at 5K intervals. You just bought the car, so you can't change how often the oil was changed in the past.
3) You have 117k, It is time for you to change the plugs. If they were already changed, make sure they were Toyota OEM plugs. The OEM plugs don't cost that much more (About $45 if you shop around). I still recommend pulling the plugs, just to see if they have any evidence of oil fouling.
​

NOTE: Getting access to the plugs is a big deal. You have to remove the entire cowl that holds the Windshield Wiper assembly. While you have the Cowl off, you might as well clean the EGR cooler, and EGR valve. This job can take a whole weekend, or more if you include the EGR cooler.

 

@ChapmanF Sorry I've scrambled the details of your EGR studies but hopefully @redv got the jist of it and can make some progress on the problem.

 

Does that ODBII reader work with the "Tire Assistant" app for android? I bought a cheap BT adapter, and it could not read the TPMS IDs using that Toyota Specific TPMS app on my 2013 Prius v. I need to buy a second ODBII reader anyway, but I don't want to overspend. I have Techstream for changing the IDs (which requires lugging around a laptop), but having a phone app that can tell me the current IDs and tire pressures would be handy if my tire light comes on while I am driving Uber.

 

I use an iPhone, but let me check if 'Tire Assistant' is available in the Ap Store and report back if it does. I know Car Scanner has an option to check TPMS but I've never used it.

 

Clean the entire egr system and intake manifold and install a Catch Can between the egr valve and the intake manifold.
ASAP

 

The oil catch can goes between the PCV valve and the intake manifold, not the EGR valve and the intake manifold.

Posted via the PriusChat mobile app.

 

Guess I messed that up that post.... even though I have installed three of them including the one on my car over three years ago.

 

It's funny, after a while you can do the install with your eye's closed, but talk about it...