Techstream EGR Valve Blockage Data

I like a lot of his videos, but this is one has me grinding my teeth. Maybe vestiges of his dealership heritage

 

Guys!

Let me put it differently.

I would never disconnect the EGR Valve or block it for normal driving.

It has its function, the ECM has it's programming, and it relies on the function of EGR cooler and valve.

OK - it maybe is possible to drive with EGR valve blocked or disconnected. It maybe will not kill the engine, but I think, it will throw DTCs, it will cause the ECM to go to sort of “emergency mode” trying to cope with the"insufficient EGR flow".

And, of course, you don't have to believe all, that this guy in the video says - I will clean my EGR valve, cooler, and intake manifold. I will not buy a new part.
I already purchased a used EGR cooler, that I will clean (not to a super shiny state) and swap with my dirty one. And I probably will buy a used intake manifold and do the same. I will probably simply clean my EGR valve (it is relatively expensive even used).

That are my thoughts to this topic

Mat

 

A used intake manifold for swapping in would be overkill, my 2 cents.

 

A used intake manifold cost here about 100 PLN (about 25$ to 26$).
A used EGR cooler has a very similar price here (Poland).

So for me, it is not an overkill

I have to do two Priuses at least, so I will clean the parts off the car and then simply swap them.
I only have to clean the EGR valve, as I do the job.

Mat

 

Whether you clean it or get a used one, do check the ski jump inside the rotor before putting it back in service. There should be no rut through it (or even partly through it). Development of a rut has been seen enough to justify checking.

 

Ditto for the intake manifold: buying a used part, it might be cracked, incompatible, who knows. And the intake is easy to clean.

 

'Tis good to see renewed activity in this interesting thread.
Here's a puzzle. Why are the EGR flow test numbers reported by my 2011 Prius seemingly improving with increasing age and mileage?
At 131441 mi. : 18.92 kPa
at 131810 mi. : 18.47
at 135216 mi. : 19.xx
at 142537 mi. : 19.19
at 150221 mi. : 19.63

Other relevant details:

• EGR cooler and valve never cleaned or replaced (but I bought a used cooler and cleaned it).
• Intake manifold passages cleaned out at 118086 miles, despite no symptoms.
• Not consuming much oil or coolant.
• Averaging about 59 mpg actual (~62 indicated)..

 

I will most probably neither buy a new valve nor a used one.
Mine is in good shape (look here: Still P0401 after cleaning egr !! should we drive it? | Page 11 | PriusChat), so I will clean it only.

Mat

 

Compatibility is not an issue - if I see the part number on the part - I can buy. Cracked - that could be a problem - yes.

Cleaning is one thing, the other is, mine is the first iteration of the part, and I can buy used revised part (part number ending with 54, if I remember it right).

Does the cleaning take 30 minutes or less? Or how long does it take to clean it (not to "new" state ).

Mat

 

Doesn’t take long to clean the intake manifold. Getting it out and back in is more time consuming. A set of bottle brushes, different diameters is useful. A fresh can of brake cleaner at hand, rags, a good sized pan to catch the mess. I would say an afternoon, start to finish.

 

That is very ... interesting.

Your Prius is behaving weird

My EGR flow looks like this:

As you see - my flow is going down, as expected, but you get some "better than expected" spikes.

So, maybe you'v got only this good spikes (very unlikely)...

Your mileage is very good. Are you traveling middle long and rather slow trips?

As you see, I have only a rather unlikely idea, why it is improving by your Prius...

Mat

 

The intake manifold is a mess in that vid. 80k miles? I wonder if that engine is an oil consumer, for some unrelated reason?
Mine @ 145k miles still seems to use oil at 1qt/8-10k miles, although I'm dong 5-6k mile oil changes, 0-16wt M1.

As for testing with a disconnected EGR valve, what kind of fuel mileage hit do you think I'd see?
Is that the only downside to doing it? (Ol'whatshisname claimed not see much if any..)

It would avoid 'The Dreaded Imbalance of EGR Flow' that seems to be thought of (here) as the reason the head gasket fails like clock work.
Are you saying they don't trust their knock sensor system to do its job?
If there is a preset ignition timing downgrade, I might be able to see that as a drop in fuel economy, correct?

 

Seems like that's saying a couple different things at the same time ... unpacking:

• it's thought (here) that the head gasket fails like clock work
• it's thought (here) that Dreaded Imbalance of EGR Flow is why

I think there might be a wider variety of thought (here). I'm not sure everyone here does think the gasket fails like clock work. There seem to be enough reports to call it a problem area, yes, but that still could mean a lot of gen 3s put on a lot of miles without that issue. Quite a lot of these cars were built.

As for why it happens, there seems to be at least a "Dreaded Imbalance" camp and a "not enough flow overall" camp (to say nothing of other camps, like the "we messed up the water pump programming" camp that Toyota seems to be in). Personally, I'd say dreaded imbalance worries me more than uniform reduced flow does, but that's just me. (Also I'm lazy, and checking Dreaded Imbalance only calls for a peek at the manifold.)

All I know about their decisions comes from what they write in their manuals. I wasn't in the room. They tell you in the manual that they've programmed the ECM to dial back the spark advance whenever an EGR problem has been detected. They don't say why they did that.

It certainly could sound like they don't think just reacting to a knock sensor after the fact is a good-enough idea when the ECM knows of an existing issue conducive to detonation. But to be sure if that's what they were thinking, you'd have to ask them.

Seems plausible to me. Ol'whatshisname assures us everything's been hunky-dory. I haven't tried it myself.

 

Cracking into my 2015 for the first time tomorrow @173k. First thing I will be doing is sending a borescope down into each cylinder to check for any head gasket issues and then I will be tackling the egr/intake/pcv/waterpump/thermostat. According to my obd scanner my egr flow is at 2.91 psi or about 20 kPa, not sure how accurate that is or if I am even remembering it exactly correct tbh.

Oil changes every 10k by dealer up until this point. Nothing on this car has been replaced or cleaned up until now either.

 

I tried to find the user Ol'whatshisname, but I do not find anything...

Is the spelling correct?

Wanted to read a little about the EGR blockage.

Mat

 

After much consideration I am going forward with Hybrid Pit to do the work.
I did request that they could take some pictures so I could post here. He said maybe if he has time. Fingers crossed.

Here are some more recent numbers for you guys:
21.21
22.12
22.92
21.79
22.38
22.36
22.42
22.12
21.79


Ill follow up in a few weeks with POST cleaning EGR numbers.

 

I had an excellent experience at hybrid pit with my EGR system. They caught my water pump before it was about to fail in about 10k miles. They we're also generous enough to clean the engine bay. Here are some of my post cleaning numbers:

23.45
22.81
22.98
23.59
21.15

It wasn't terribly dirty inside. So much so that I probably won't take it in for another cleaning until 200k. Currently at 115k achieving 60+mpg

Thanks for everyone's help

 

At what speeds?
Those numbers don't show much improvement, no?
How much did they charge you?

 

Well I asked for it. I was going to do it myself but it was too much work.
$1450 about.
I was showing your perfect numbers. But I did it as preventative maintenance.
I'm getting a 10% improvement. Is that not good enough?

 

The key thing is to remember is: "preventative maintenance".
That's why you change all the oils, filters, etc. Change them BEFORE they fail
and cause expensive damage.