Ran into this in my news feed, thought you guys might enjoy it if you haven't read it already. Pretty good info.

https://www.torquenews.com/8113/does...ld-start-knock

 

So why would a new one have the problem?

A new car is going to have a good head gasket and an open EGR system. I was told the new updated Intake was for moisture and had larger EGR openings -- maybe the smaller intake opening created more vacuum in the EGR system to keep it free?

The big failure in the system is from the beginning ... the intake spot for the EGR systems picked up soot from the exhaust.

Also -- Lexus replaced the intakes in both of our CT's (2015) under a service action


The new intake did eliminate most of the problem -- although we did not have it like we did in our 2011 Prius. So on a new one with nothing else up -- the intake was part of the issue

 

definitely interesting because I did a full clean of my EGR system when I got my 2011 CT200h at 110k miles. The cooler, pipe, valve and manifold all had some build up but nothing close to what you see on the internet. I had no knocking or any issues, I simply did the cleaning out of preventative maintenance. I ran 4 cans of carb cleaner through all components and pressure washed the manifold and cooler until they were completely clean. The car was fine for another 10k miles but I started getting cold start knock one morning. I ignored it and it came back a month or so later. The car still had no codes or anything and ran fine. Doing some more research, I read that the manifold was difficult to clean so I purchased the revised one and installed it. This fixed the issue completely and I haven't seen the knocking come back at all in 5k miles. So, the manifold apparently can make a difference... at least it did for me.

 

I can't recall ever getting cold knock ever since I got my new manifold as well.

 

We would get it on colder day -- typically in the early fall where the temps had fluctuated -- car had been sitting for a couple

 

Sunman6 : That's the strange thing about this problem. Some have it and others don't ... or not as much. We had 4 Gen 3 Prius and two did and two did not .. all with over 200k.

The intake IMO is the cause of the rough start problem -- knock. Toyota changed it twice. The first two years of production had the original and then later -- must have been after 2016 they updated it a second time. Our two 2015's would have had the second version when produced -- Lexus replaced both under the service program. I asked Lexus to check the EGR tube when they changed the IM --- they told me both were cleaned and not very dirty.

In states with CARB emission standards they coverage is 10/150k -- our cars are in NJ so covered. Lexus would do it on customer complaint -- Toyota only if the CEL came on.

 

Can you elaborate on what you mean with that last bit? Thanks

 

The extended emission warranty only kicks in if the CEL light comes on or the car fails the emission inspection. So if the knock is bad enough to trip the CEL you can take it in and tell the Toyota dealer to fix it under the warranty. Same if you have a "failed" report from however your state does emission inspection. In many states with CARB this 10y/150k.

The Toyota dealers are not authorized to fix what Toyota called an operational nuisance -- they just say it's a problem that can't be duplicated or is not covered unless it causes the car to fail inspection.

With Lexus -- they fix things for customer goodwill in ways that Toyota does not. Lexus had a service action w/ customer complaint -- I went to the dealer with the action and complained.

There are many items that are covered under this 10/150 -- the battery for example.