Visual Differences between updated Intake Manifold

I went down this rabbithole last night reading up on every comment and was dismayed to learn that x91 was not a new, better designed part. My Prius probably has x50, so I will just clean it up for now and call it a day.

 

I'm pretty sure Toyota introduced it because they did consider it an improved design.

On the other hand, maybe it won't matter to you if you don't experience the issue they improved it over.

 

It is certain the intake was an improved design. It is designed to eliminate codes stored in certain cold starts when combined with an ecm software update.



Toyota also updated their gen3 head gasket, pistons, rings and egr valve. All in an attempt to make the gen3 engine more reliable. In fact 2017-2021 gen3 engines sold overseas have a good reliability record even though they share the same gen3 engine. Which makes JDM engines of that vintage good options now or professionally rebuilt engines using those parts a better choice.

 

Somehow I keep forgetting that more than one TSB announced revisions to the gen 3 intake manifold.

T-SB-0010-12 was the one about snorting condensed water from the EGR passages. That's the one I usually remember. It said to update to a -52 manifold in the first revision, then later to -54.

T-SB-0103-12 was about the throttle body sticking open. Looks like I knew about that four years ago but I usually don't remember it. It says to update to a -91 manifold.

I don't think I had ever even stumbled on T-SB-0116-15, which is also about replacing the manifold, this time for misfiring when driving with EGR active (the usual effect you'd get if the passages were gunky, fixable by cleaning them). That one also pushed the -54 manifold (rather than taking the time to clean the existing one).

The most interesting one I forget to think about is T-SB-0103-12. The symptom is a P2111 code, which is when the ECM tells the throttle to close and that doesn't happen, and apparently that was (not) happening below 23 ℉ (−5 ℃), and they somehow meant the -91 manifold to improve that. Hard for me to guess why, but that might be the one that comes closest to giving a reason for the weird griddy gasket under the throttle body.

Edit: typoed the number of a TSB

 

As has been discussed earlier in this thread, there is no x91 manifold. The x91 is a reference to a x54 manifold kit with all the gaskets included. So the latest design seems to be x54.

 

I had seen that discussion, but I might not be all on board with the conclusion yet. Why?

A few reasons. First, this would be a departure from what we're all used to where kit part numbers start with a PNC of 04xxx-. This would be an instance of a kit having the same PNC (17120 for an intake manifold) as the non-kit item, which would be weird.

Second, I think the main evidence advanced is that some have ordered by the 17120-37091 part number and received a manifold that has 17120-37054 visibly marked on it.

But that kind of thing isn't terribly unusual; we've had recurring discussions on PriusChat about the way Toyota parts sometimes have numbers visible on them that aren't their part numbers. There can be different explanations; the visible number might be an engineering number, or the private part number of some constituent part, or maybe the number of a rough item before some kind of finishing step.

I'm not sure what's happened here; it's again weird, having the visible number be the valid number of a previously-marketed part. Did they find a way to take New Old Stock x54 manifolds and rework them to be x90 / x91 equivalents? Beats me. But it wouldn't be the first time that ordering by one number gets you something with a different visible number on it.

Also weird that T-SB-0103-12 has a big 'HINT' right in it saying the number on top of intake runner #4 is the part number. So, weird that they wouldn't grind or melt or in some way change it if they have, indeed, reworked the part somehow. Weird also because it would lead you to keep endlessly replacing the part if the customer comes back, because the x54 number is included in the list of 'PREVIOUS' numbers to replace.

So, I totally can't say that I have the explanation. But I'm also not sure "it's a kit" is quite it.

 

You are definitely onto something with your hypotheses. I was, until recently, not aware that the kit numbers all started with "04...". My experience comes from ordering the EGR valve kit (04004-58137) and then seeing the valve listed in other places as (25620-37130). So it took some research to finally figure out that the kit came with gaskets and the regular valve didn't.

You would think a competent dealership would be able to shed some light on the progression of manifold part numbers, but we are probably expecting too much from them.