2nd gen start knock but no codes for misfire

I agree. By ear it would be difficult and this is very often misdiagnosed. So either pull the valve, inspect, and see how easily it moves... clean if needed. Then check solenoid operation. To test electronically, use an app and ODBii dongle or Techstream to monitor ignition timing during start and road testing. Sluggish or very little IG Timing change should be obvious.

 

Notice there's a little bit of bantering-past-each-other going on here. While drone13 is talking about the solenoid valve (located next to the intake on the 1NZ engine, easy to get to, maybe $20 in some knock-off form), mr_guy_mann refers to the actuator, which is the thing the solenoid controls (on the intake camshaft, harder to get to, less likely to be $20).

Again, as I haven't heard of the issue myself before, I don't have an opinion, just trying to keep the terminology straight.

The Honda service bulletin mr_guy_mann mentioned is certainly interesting.

 

Your oil has to be really bad to gum that thing up. Again pull the VVT filter out see if it’s clogged. It’s a hex head bolt flush with the block right under the solenoid.
It’s there to prevent this very occurrence and inspection of it will reveal if that’s an issue also easy to take out the solenoid one 10 mm bolt pulls right out. Top of block at cylinder #1.
That filter hex hex is really on there super tight. Use a quality bit to go after it not a cheapo it made a really loud crack noise when I busted it loose with a breaker bar with a pipe extension.

I wrote up a full detail on it a long long time ago. Search VVT .

American g2 has the coolant over flow tank but under the plastic rad cover is the rad cap on the left. Yours looks a little different. Forget the rad over flow tank it’s useless it could be full and the rad empty. Disregard it.

mine the main rad dump bolt is on the drivers side on the bottom engine side.
Have to fight around all the coolant inverter hoses and whatnot. It’s a white plug.
It’s a big plastic plug take it easy on it can’t remember what size.

 

I did have one Gen2 that had a stuck VVT solenoid. That one did not have any rattle or noise, but did throw a code (P0016?) because the stuck solenoid prevented the cam timing from moving at all. Techstream (or any scantool) only shows VVT data when you use the VVT bidirectional test- so you can't monitor anything on startup or during a test drive. Only way to view what is going on is to scope the cam and crank sensors with the solenoid.

This car had a clean VVT filter so some tiny spec of grit must have got past it and jammed the solenoid. Couldn't get the plunger to move 100% smoothly so it got a new part.

Posted via the PriusChat mobile app.

 

The part in question is an assembly. The valve and solenoid are one part, not separate. This is the Toyota part that is known to fail in many Toyota models, and particularly in vehicles that have not been well maintained and in particular not doing timely oil changes. But you are right, this is not the complete VVT system, but this is the most common part that fails so worth a quick check. And yes you can get the part, 3rd party Chinesium, from Amazon for under $20. If after testing and determining if it needs replacement you can get the original Toyota part #15330-21011 from reliable sources like toyotapartsdeal.com for $83.00 if you prefer OEM. Or from Ebay (genuine NIB Toyota part) for $53). The OEM part is cheaper than I expected. Here is the part for reference:

15330-21011 - Toyota Parts Deal

It kind of sounds like this car was rode hard and put away wet, very little maintenance if the radiator condition is representative of vehicle maintenance. So since the symptoms match the known failure characteristics If the vehicle were mine I would check in hopes of a cheap easy fix. Please note, I never said this is the problem, but it is worth checking and it's easy to check.

For the radiator, I would just buy a new one and replace after flushing the system really well... including the thermos. Without the additive package for aluminum radiators it is likely not in great shape and a new one is under $200 even at places like a local auto parts store. If you're not going to keep the car, just fill it with water again and sell it I guess.

 

You have once again linked to the solenoid valve (which I also linked to in #24), but once again you are leaving unmentioned the actuator, which is a separate part. At this point it is hard for me to tell whether it's just a matter of reading/typing too fast, or that you may not have realized there was another part to the system, which is the part mr_guy_mann was referring to.

 

The reason has been explained several times now. This is a common known point of failure for many Toyota vehicles and it is very easy to check. If you read my last post you will see that I did say this is not the entire VVT system, just the most likely part to fail. Please re-read my last post.

The comment about reading/typing too fast is dismissive and disingenuous. Please moderate your responses @ChapmanF . I think @mr_guy_mann has made a valuable contribution to the thread also, but it is a different response and not what I'm referring to. I think after checking a simple to fix known failure point it would be quite reasonable to dig deeper with some Techstream data collection and analysis.

 

We seem to have moved a little into retcon territory now.

In #14 I asked you to please be specific whether you were finding the problem in the "solenoid valve" or the "actuator on the camshaft".

You replied in #20 "the entire part, valve plus solenoid is a single assembly you buy", so you were still talking about the solenoid valve, and either missing or ignoring the distinction between that part and the actuator.

In #24 I pointed out again that the solenoid valve and the actuator are separate, and that you were talking about one and mr_guy_mann was talking about the other.

At that point I was more concerned with just keeping that clear for other readers of the thread, so it was more of a clarification than a question. But you replied anyway in #27, saying "The part in question is an assembly. The valve and solenoid are one part, not separate", which no one had suggested they were, and for the second time either missing or ignoring the distinction being made between that entire part and the (entirely separate) actuator.

I do see the "this is not the complete VVT system" in your post there, but I am not sure it much changes the fact that you twice replied to posts that distinguished your solenoid valve from the actuator, and both your replies were close variants of "that's one thing not two".

As long as we now all agree (right?) that there is a solenoid valve externally accessible near the intake, and an actuator internally on the camshaft, and those two things are not the same, then that's where we needed to get to, even if the road leading there could have been smoother.

I am sorry if anything I wrote seemed dismissive, and I will let 'disingenuous' slide. I certainly don't set out to be immoderate; it usually takes at least a couple iterations to get me there.

Getting back to where we could have been without the detour: this is an interesting possible explanation that I haven't seen covered much on PriusChat before. It is also interesting that both you and mr_guy_mann have raised VVT as a possibility, but seem to have different views as to which of these two separate parts is the most usual suspect.

In support of the actuator being at issue, mr_guy_mann has supplied a very much on-point Honda service bulletin. You say in #30 that it's the valve, rather, that is "the most likely part to fail."

I am curious (and I don't mean this sideways; I ask for references because references make threads better), are you aware of some articles, bulletins, youtube vids, whatever, also implicating the solenoid valve as a likely suspect here? Do you have some of those to share? Is your judgment of what's "the most likely part to fail" based entirely on your own experience (if so, roughly how many cases?), or did you hear about it from someone, or read about it somewhere?

Again, I'm not asking with the aim of poking holes in your opinion. I'm asking for the purpose of getting the information into PriusChat where people can find it.

 

I will say that my experience has been that the VVT solenoid is (in general) more likely to fail than the actuator. But that failure modes I have seen in the shop are: solenoid sticks/jammed "shut" (no VVT operation or movement and sets a code), solenoid sticks/jammed "open" (VVT fully travels with poor engine running and sets a code), solenoid sticky or "sluggish" (VVT doesn't move quickly enough and sets a code), solenoid open circuit (VVT inoperative and sets a code). See any themes here? I haven't personally seen an instance where a solenoid fault caused any type of rattle noise from the VVT/engine. But that's just me.

 

I opened up my 2nd gen cam sprocket- I was surprised to see that it does not have the hole for the pin to lock into like in other Toyota models. See my video at about 5:35. When I was changing my timing chain, I noticed that the cam sprocket rotated back and forth freely and was worried, which led me to open it up to inspect. It's got all the internals, except the hole for the pin to lock into. Pretty weird!

Great info in this thread- I'm dealing with a "misfire" (timing?) issue with no codes and am wondering if it has to do with the vvt system.

 

Other than all those pesky codes being set, no.

Good information. Say, in your cases where the VVT response has been slowed, have you looked at the monitor test values for "IN VVT STUCK"?

I pulled up mine and the test value is 0.00 (seconds, I believe it is testing how long it takes to change the valve timing by a certain amount), which looks very good. (I pulled it up only out of curiosity, not because I suspect any VVT problem.) But 0.00 looks almost too good, so I wonder if you've actually seen it be non-zero in cars with a problem.

 

Haven't checked VVT monitors on Toyotas for this- will start doing so and see- beginning with mine. The cars I had worked on I was able to view VVT scandata and did action/reaction testing. Can't remember right now if the last one was a 2GR V6 or another make .Command a change then watch how long before VVT angle responds.

Yes, 0.00 sounds like a default value, not a real result. Of course since it's engineering data, you don't know if that monitor was actually used on that car or not.

 

I'm kind of late in the discussion, but the original question included the possible causes of cold start rattles. If I'm not mistaken, doesn't the Prius (at least the Gen 2) have a start up process where initially it runs rich. I seem to recall the rational was to heat up the catalytic converter as quickly as possible. I don't notice it as much anymore because the engine doesn't run as smooth as it once did, but I remember that for the first minute or two, it sounded like it was misfiring, or at least running roughly. Could this start up procedure be part of the cold start rattles that are being asked about?

 

With the recovery bottle, I think that the intent is not to have any air in the coolant system, and the expansion due to heat transfers the coolant into the recovery bottle. As the coolant cools down and contracts, it can then draw fluid from the recovery bottle back into the system where it had been before. The extra coolant in the recovery bottle is to compensate for losses due to small leaks over time. If there is no air in the system, there should be very little residual pressure since the fluid isn't compressible, but can expand and contract some.

I didn't take mine out today due to snow and ice, but the next time I drive it, I'll try to remember to try taking the radiator cap off after 3-4 hours after sitting and see if there is any residual pressure.

Regarding the sandy material, I wonder if that could be from the radiator stop leak that you said you thought had been used. I'm sure it has something like sand in it since it blocks the leaks by depositing material in the gap that is causing the leak. I'd think that something like fine sand would be a good aggregate. The idea though is to plug the small leak, but at the same time not clog the passages in the radiator. It's probably something that is hard to flush out later, and they probably expect the radiator to just be replaced eventually.

 

Haven't tried the radiator cap yet, I needed to drive the older Subaru Forester today. I haven't forgotten.