Loud thunk, thunk, thunk... at cold start up?!?

have you come across any of the 'cold start noise' threads? i don't know if you're hearing the same sound, but those are caused by starting the engine, usually moving it around the yard, and shutting it down before the warm up cycle has finished, leaving unburned hydrocarbons in the intake manifold, causing detonation on the next start up.

 

Welcome to the knock club, membership continues to grow. 2015 members come this way to sign the petition to have toyota resolve the EGR design.

 

Yeah, all of the above, and the EGR circuit starting to clog. It's the albatross of the third gen. Good thread:

EGR & Intake Manifold Clean Results | PriusChat

Watch the @NutzAboutBolts videos too, pinned at top of 3rd gen maintenance forum.

And Oil Catch Can:

Oil Catch Can, Eliminate that knock! | PriusChat

 

Wow 6 active threads all with the same problem... Someone needs to search for EGR

Pixel XL ?

 

No way, whose going to hand feed them then?

 

Why be snarky. The person is brand new and asked a simple question. If it bothers you, don't answer! Cut back on the Jim Beam so you don't get so cranky.

 

Just making an observation that the "Maintenance and Troubleshooting" forum is becoming an "EGR Maintenance and Troubleshooting" forum. Maybe sticky one of the EGR cleaning threads and add all symptoms and repair methods to it?

Save the Jim Bean for a special occasion.

 

That's Ok. Maybe it's because that stinkin' EGR is such a major problem? And common problems often dominate a forum. No big deal. Keep up the good work, fellas.

 

@Hangfire said that the car has only 35,000 miles. It does not need EGR cleaning. EGR cooler carbon blockage doesn't get to be a problem until at least 100,000 miles, and probably more like 150,000 miles before issues will manifest. I wouldn't touch it before 100,000 miles unless there is a P0401 code. It's also a 2015, so it already has the improved EGR valve (part number 25620-37120 vs. old part number 25620-37110) which is less prone to sticking.

A new poster won't know the proper search terms to use, and might not even make the connection between "thunk-thunk-thunk" and "knocking" that is covered by this stickied thread: NEW!!! Service Bulletin for Engine Knocking at Startup T-SB 0012-10 | PriusChat

You'd also have to read 700-800 posts in that thread before you realize that the initial post in the thread is outdated. The intake manifold updates mentioned do not fix the problem, and Toyota reversed that TSB. So, really, it's hard to blame a new poster for not being able to find where the problem is covered.

The oil catch can is the real DIY solution in this case. See: Oil Catch Can, Eliminate that knock! | PriusChat

 

has it happened again?

 

Yes. My point was that there should be stickied threads for EGR cleaning and OCC.

The stickied "NEW!!! Service Bulletin for Engine Knocking at Startup T-SB 0012-10 | PriusChat" doesn't mention the real solution (OCC) until page 45/49. There are almost 1000 responses to that thread. A really smart newbie will probably give up after the first 200 replies. Quoting @danlatu: