2011 Prius engine vibration on cold startup

Welcome to the knock club, we’re always accepting new members.

It’s beyond the valve, you’ll need to look at videos related to cleaning egr circuit, intake manifold & OCC installation then perform all of the tasks if you want a long term solution.

 

Sad but true. It's like you've wandered into EGR triage: welcome, take a number, the waiting area's over there.

Some boiler plate info:

The simplest way to see where you're at, is to check the degree of carbon build up in the EGR pipe, a stainless steel connecting pipe between the EGR valve and intake manifold. Watch @NutzAboutBolts video #16 here:

Nutz About Bolts Prius Maintenance Videos | PriusChat

Two or three other videos linked there too, for the full cleaning of the intake manifold, full EGR clean, and Oil Catch Can install.

Good thread:

EGR & Intake Manifold Clean Results | PriusChat

Another:

Oil Catch Can, Eliminate that knock! | PriusChat

Some tools worth having:

E8 Torx socket (mandatory)
E6 Torx socket (optional, but good to have, to remove the throttle body studs from intake manifold)
3/8" ratchet wrench, regular and long handle, flex head, you can never have enough (or 1/2 plus reducer)
1/4" ratchet wrench, or 3/8" to 1/4" reducer
Ratchet extensions: you can never have enough
Long needle nose piers, straight and bent tip
Ratcheting 12mm box wrench (optional, but makes disconnection of the EGR cooler from exhaust easier)
Torque wrench (3/8" and 1/4" both good to have)
Floor jack and safety stands (or ramps): basically some method to raise front, if you need to take underpanel off, which you may need to, both for access and to recover dropped items.

Comment regarding clamping of coolant hose, mentioned and or shown in videos:

1. When removing the intake manifold for cleaning, you do need to lift the throttle body off the intake manifold. Still, the coolant hoses connected to the throttle body have ample slack, enough that you can leave them connected, and just tie the throttle body to something adjacent, say the inverter wiring harness.

2. When removing the EGR cooler, removing coolant hoses is necessary, but if you drain 2 liters/quarts from the radiator drain spigot prior (into a clean container), the coolant level in the system will be dropped below the EGR components, and you won't spill anything. Just be sure to not tip the cooler when lifting it off (and catch the rear gasket): there are a few tablespoons of coolant trapped at the lower back corner.

Pour that into your previous drained coolant, and when done pour it back into the reservoir. If you've got the coolant bleed bolt (2010, 2011 model years), leave it open while pouring the coolant back in, till coolant starts coming out. For later model years, leave the topmost coolant hose on EGR disconnected till coolant starts coming out. Also, might help to burp the main radiator hose as you pour the coolant back in.

Plagiarizing the lower half of a Garry Larsen cartoon:

 

I get the sense dealership service departments are woefully "behind the curve". The will be reluctant to clean anything, might insist on replacement, which is very expensive: the intake manifold, EGR valve and EGR cooler are each roughly $250 apiece (some more, some less). Replacement of all 3 I would guesstimate 6 hours labours? Most frustrating: you will likely be arguing with them every step of the way: Toyota and the dealerships are totally passive-aggressive in their approach to this.

The few dealership experiences I've heard of here: were cases where the clogging had gone on hopelessly long, codes were showing for insufficient EGR flow. Then what they did (under warranty) was replace JUST the EGR valve, which basically leaves 2/3's of the system still clogged. It's a sick joke.

If the shaking is bad when the car's sat for a couple of days, sounds like a slow coolant leak from the head gasket, and over time more accumulates. Then when you start the car the engine is struggling to compress (incompressible) coolant. Most likely in cylinder #1, at least that's where it tends to start, due to the design of EGR inlet into intake manifold.

 

------------> (INcompressible)

 

Thanks, fixed. I typed that first, windoze told me it needed spell correction, and I thought ok. So it stripped out the "in", and I didn't notice, lol.

 

Great video.

The EGR - head gasket failure is a common problem for this generation of Prii at higher mileages. But ...

A completely different thing to consider would be one or more stuck hydraulic lifters.

Those are little cylinders that fill with oil to provide automatic adjustment of valve lash. They are supposed to instantly fill with pressurized engine oil, adjusting to the exact right size to provide the interface between the camshaft lobe and the valve. But dirty oil, wear, and age can cause this not to work perfectly. After sitting for a while, the oil can leak out of individual lifters (not generally a problem) and the lifters can compress (not generally a problem). But then when starting up again, engine oil pressure is supposed to very quickly fill the lifters, allowing them to very quickly re-adjust - and that is what sometimes fails to happen properly. If things are not too bad (as your case might be, if this is indeed the problem) once things get a little warmer, shake free, etc. things settle out and all is good.

Google search on "stuck lifter" should give you a few centuries of reading.

As far as what you might do if this is the problem - easiest things are often an oil change, perhaps combined with some sort of pre-change additive solvent, or post-change additive. I don't have any specific recommendations, but if I had your problem I'd research down that avenue for things addressing stuck lifters. Hopefully it is something that can be fixed without actually opening anything up.

And the EGR thing, even if that is not your current problem, is an important thing to be concerned with. I did the full EGR/intake manifold cleaning and oil catch can install recently, and my 2012 only has about 65k miles. Glad I did all that.

 

Getting the cooler out and cleaning is NOT as bad as some people make it seem.
It's not super easy, will take time, but very doable if you take your time, follow the instruction,
and have the correct tools.
If you have some mechanical skills, you can do it. When you watch the video's, it will look
overwhelming, but if you take it one section at a time, you'll get through it before you know it.