Techstream EGR Valve Blockage Data

Hi! I have a '09 Prius III (~180k miles), cleaned the whole EGR system approx 1,5 year before.
The car did run fine since the last two 3 months.
After that i got rough idle/cruising and P0401. Cleared DTC then. There isn't any DTC since then, however ICE runs roughly sometimes (when cruising with constant RPM -typical "EGR valve is opened" usage-, or when car is idling).
I have Techstream data when i got P0401:


Maybe EGR couldn't close enough how it should be in my case? Because my test result was exactly 0.00, as shown the picture.
MAP sensor was dirty as hell, cleaned it with proper chemicals (without any phisical contact ofc), but it didn't help.
So car is running, no DTC, but sometimes make rough idle (not on cold start!), and on mild cruising.
Did EGR step position test too, ICE starts to rough idling around 11-15 steps, however when i decrease it to 0, then it not really makes any sense to make idling smooth again. What do you think? Maybe there is still some debris on the EGR valve stem itself, cause stucked valve?

 

Presumably when you say it’s a 2009 it still is a 3rd gen Prius? Your location being Hungary, the convention is to identify by build-date? I have a North American “2010”, as described by Toyota here (Canada), although its build-date was August 2009. Info

Did you clean the EGR passages in the intake manifold?

what’s the miles?

the EGR valve may have internal damage, isn’t performing properly. @ChapmanF may chime in with more info.

 

You cleaned the map sensor, not the maf sensor?

Probably an egr air leak or a sticking egr valve. Try a block flow test. There is a revised egr valve available for a first year gen3.

no cost egr block flow test

 

If you're getting a very low flow number, or a P0401 code, doesn't hurt to check the valve for a rutted ski-jump, which can contribute to that.

 

Hi Mendel,
Thank you for your reply. Yes, it's a 3rd gen for sure, produced in 2009 via Toyodiy according to VIN number. 2nd gen doesn't have EGR at all, IIRC
It's a very early 3rd gen, zenki model of course.
~180k miles in her.
Sure, i've cleaned the intake passages, EGR cooler, everything.
Sorry for my bad english.

 

Thank you! Yeah, i've cleaned the MAP, located next to the throttle body, over the little oil swimming pool
I've already bought a revised one EGR, but before i replace it i'd like to make an exact diagnosis as well. We have 3 HSD in our family, so this revised EGR valve could be useful later too

 

Hi Chapman,
Thanks. Yes i know the "ski-jump" thing, i've checked it. It's been in quite in good condition, like an unmolested "ski-jump".

Hi ChapmanF,
Thank you, I've checked the "ski-jump" already. Seemed absolute fine and mint

 

Presumably then the car’s first EGR cleaning happened around 150~160k miles? That’s quite late; I’d be on alert for head gasket failure signs: dropping coolant level in reservoir, engine shaking during cold-starts.

 

@RWD Any initial test is to physically block the EGR passage and analyze effects.

The professional TCCN video linked by @rjparker shows this.

Also - as you have techstream - you can force close this valve via the EGR active test with engine running….

Step 0 is closed valve.

If the EGR valve is clogged, physical block analysis - compared to the effects of step zero - with reveal this issue.

 

Production of the 3rd generation began mid-way through the 2009 model year, as car model years are conventionally defined as beginning circa October. Just to confuse everybody, Toyota designated the early ones as 2010s in the US, but 2009s elsewhere. Once upon a time (see orignal Ford Mustang, for example) mid-year introductions were unofficially designated something like "2009½," as it would've been in this case.

 

For anyone about to use that EGR step active test, it's good to take a look in the repair manual for some things Toyota wants you to be careful about, some collected in this post in 2019.

Generally, when you'd be doing such a test, the engine will be idling; its target EGR step at idle is zero anyway. In the places where the repair manual suggests using the active test, it is generally having you override the normal zero target with a higher step, to see what happens then (and then leave it the way you found it by setting back to zero).

Any time the target step is zero already, setting it to zero with the active test doesn't do anything more to force the valve closed ... if the ECM targeting step zero hasn't closed it already, it's not like you get a more forceful step zero by requesting it in the test.

 

Thank you guys, i'll inform you about the results.
I'll check the whole EGR system again, looking for leaks and/or damaged/stucked EGR valve "internal" (EGR valve stem).

 

Correct. Any reasonable and objective person seeking priuschat instructions and help, would likely understand this? The EGR valve step test are made our of steps. Apx 120 steps for this motor.

Why don’t you link this EGR active test manual excerpt, if there is such a chance of misunderstanding?

Your helpful input could make it obvious how to use TS active tests...

Do you work for Toyota perhaps? That would explain a lot… ;P

 

Copyright infringement?

Anyway, never really looked through this personally, but this is maybe it:

 

This has been published many times, and against, Toyota is not Nintendo. They have never seeked any infringement on any/this publishment, as I know of.

Please inform us if any indication otherwie: I doubt you will find it…

This material is not copyrighted in any global legal sense. It’s just paywalled for profit and restrictionism…

Copyright are soon not applied to repair manuals in the EU. It’s just not logical if you demand Apple etc publish correct repairs by law.

And the current analysis is not beneficial to any user of any car, on priuschat or otherwise. Anyone referring to copyright are supporting stealerships and not free information. Especially when it’s a legacy car.

 

Step 110 is fully open, according to the post from 2019 that I linked to above.

The post from 2019 that I linked to above includes a short rundown of the points from the repair manual, and also how to find the full procedure in the repair manual:

The P0401 excerpt that Mendel posted is another of the multiple places in the manual where the same instructions appear.

A review of my years of posting history here will show that I have posted short excerpts from the repair manual, portions of wiring diagrams, and so on, quite often and generously when they directly pertain and will help explain a point or solve a problem, but that I generally do not not post entire sections or multiple pages of material, as some other members do. I don't criticize others for doing that; they'll make their own ethical judgments, I'll make mine.

I also contributed heavily (though not as much as Elektroiengenieur) to PriusChat's page about how to access the repair manual and other docs, including the avenues that may be low-cost or free depending on where you are:

Toyota Service Information and Where To Find It | PriusChat

US copyright law is what I understand best. I don't know much about Sweden's, and I don't know how much you know about ours. Something interesting in the US approach is that there is a "fair use" defense, but there is no simple bright line for what is or isn't fair use. There are some guidelines, and they involve questions like how large or complete the portion copied is, the purpose of the use, and the effect of your copying on other people referring to the work itself. Essentially, you think you are making fair use of a work as long as you'd be comfortable telling a judge and jury the reasons you think it qualifies. You did make fair use of the work if the jury agrees.

I don't work for Toyota, but my career has been spent in a profession that's unforgiving of copyright infringement. When I post on PriusChat, I am using my judgment both in the hope of avoiding legal harassment for myself, and of avoiding legal harassment for Danny, who is kind enough to provide this forum for us to chatter in.

Everybody who posts here will make their own judgments as to what to post or not post. Yours are yours, mine are mine.

 

@ChapmanF I do respect your knowledge and opinions - but the lack of respect and acceptance of any other information beside your sources seem to be lacking.

That is not scientific and objective analysis, it’s the absolute opposite- and to the detriment of any open discussion of anything.

You seem to take this very personal, and that is sad and is not benefiting anyone - besides your ego perhaps…

I am university educated and work in biological science and do not accept company statements as anything near scientific facts, unless proven by objective sources.

It’s in my open mind the absolute opposite - it’s written and wishfully copyrighted (according to US law) to assure normal people don’t know anything about the science / structure behind any system.

It’s declaring everyone beside Toyota technicians an idiot due to lack of valid information. This is unlikely your goal.

 

Toyota seems one of the more stingy auto manufacturers, when it comes to sharing basic maintenance info. Honda Owner's Manuals always included oil change, transmission fluid change, wiper insert replacement, basically the easy-level DIY stuff. No such inclusions by Toyota, which perhaps invites piracy.

There is one member here offering a certain Repair Manual, and "solicitating donations to his coffee fund", that's perhaps tugging the tiger's tail a bit too hard?

 

That effort is rather incomplete and excludes any wiring diagrams. All offline downloaded versions lack functional links for complete instruction. In addition they are written for Toyota trained techs.

 

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