Gen 4 EGR cleaning at 360,000 miles

Wish there was a super-like button.

@Raytheeagle had similar “fun”, extracting EGR components on his prime.

Sounds like they sorted out the carbon clogging. A stark difference from gen 3.

The prodigal son parable comes to mind.

 

Yes, that would be good. Gen 4 surely has the same built-in emissions monitor that you can ask about your EGR flow score any time you want, same as Gen 3. Starting a similar Gen 4 forum thread with some mileages and flow scores would be a way to get some very useful information, with a lot less trouble than bungeeing the inverter out of the way.

My guess is that there will be some Gen 4s, maybe with fewer highway miles, that might show worse flow scores than this one did. (For that matter, it would have been nice to know the score for this one!)

 

This thread is maybe more interesting to third gen owners: 4th gen Prius, with all the lessons learned from third gen EGR, 360k miles, never had a cleaning, next to no carbon, and no head gasket problems.

a couple of cold comforts:

1. the #%*!# 3rd gen EGR components are easier to access (amazingly).

2. our exhaust heat recovery components aren’t having coolant incontinence issues.

 

Gen 4 cars have a different EGR system because the auto industry was researching a different EGR chemistry during the years Gen 3 was in design and production, and there are journal papers on the new chemistry, "catalyzed EGR", that were published during that time. Gen 4 uses that newer approach, which hadn't really been commercialized at the time Gen 3 was in design. Taking the gas from after the catalyst changes its chemical make-up and changes its effects on combustion, as the journal papers describe. And the components for catalyzed EGR have to be larger, because the gas from after the catalyst is of lower pressure. Everything must be proportionally larger to get the right flow.

So there is a good deal more to the change between the Gen 3 and 4 equipment than just "lessons learned from third gen EGR".

As this thread's in a Gen 4 forum, one hopes it'll stay interesting to Gen 4 owners, who can use it to collect their own data on how a wide sample of their own cars are doing (not all of which will have put on 360,000 miles in a handful of years).

There won't be anything wrong with us Gen 3 owners peeking in, but we already have our own thread for Gen 3 mileage and EGR flow reporting. We can leave the Gen 4 folks a little space to have their own.

@jerrymildred, what was the year of this 360,000 mile car?

 

Yessir...

 

most gen 4 owners haven't a clue, unless they owned a defective gen 3

 

3. The 3rd-generation engine coolant pump is less difficult to replace, as I understand.

 

Hi Jerry thanks for this write up! Its been 10 years and this is the only info i can find on the 4th gen EGR system lol. Im having a stumbling/misfiring issue. It drives fine cold but once its hot. It won't accelerate. It does has a very slight rattle on startup maybe once or twice a week. Im not losing coolant and the plugs look good. I have a replacement EGR system from my last swap i could install but it looks like a pain with the inverter in the way. I feel like if it was a coil or injector, id be getting a code. Any advice on how to proceed would be great.

 

Im having EGR symptoms on my 4th gen :-( ....it started with occasional rattle on startup but not constant or dramatic.. No codes,coolant is steady and plugs look good so i didnt think much of it. Now im getting stumbling/missfire symptoms once its warmed up, its almost undrivable but Its fine when it cools down. Does this sound like an EGR problem? I wish i had a check engine light to point me in the right dirrect. Any advice? Thanks in advance.

 

4th gen EGR had significant changes and has not been prone to clog or malfunction.

Early Gen 4 years have had coolant loss issues due to leaks in the exhaust heat recovery system.

what’s the miles and how long have you had it?

 

2016eco2 created a thread about his car over here https://priuschat.com/index.php?posts/3608514

It would make sense to keep all the discussions in that thread.