My Prius dead again, with techstream this time.

There is no solenoid associated with the EGR valve.

The valve is driven by a rotary stepper motor acting on a threaded valve stem. The black plastic cover on the valve encapsulates the stepper motor windings and encloses the rotor and bearings.

Other than the stubbornness of the two Phillips screws, which respond well to a light touch with a hand impact driver (the kind you bop with a hammer) or a seized-fastener removal tool like the Lisle or Thexton, there is nothing especially difficult about disassembling or reassembling the valve. The design is straightforward; you would kind of have to try to mess it up.

 

I admit that I'm wrong about it's construction, Chap. I am inquisitive, however, why you needed to disassemble it; other than to find what you stated.

I'm more concerned on how to fix grom's problem.

 

Disassembling it is an easy way to check for freedom of movement of the valve pintle. It can even be done with the valve on the car, only two Phillips screws to remove. (If it doesn't move smoothly, it might be possible to free it up some working only from that end, though I have never tried that. Removing the valve and de-caking the carbon from the business end of the pintle might often be required.)

Mine had some corrosion on the metal bits inside the stator, thick enough to impinge a little on the rotor. That was easy to clean up, making sure the rotor spun smoothly. It was also easy to collect some of the grease that had retired from the threads to rest in other locations, and put it back on the threads.



In ozmatt's thread, there was an interesting failure mode where the ski-jump-shaped stop molded into the rotor had developed a carve-out:



The stop defines where the valve's "full closed" position is. If the stop gets carved through, the rotor can go additional steps in the closing direction, beyond "full closed" (which is possible because of mechanical play).

What happens then is interesting. Because the ECM only knows the valve position by dead reckoning how many steps it has moved from "full closed", if the rotor actually goes beyond full closed when closing, then it never gets as open as it should when opening. That was ozmatt's problem.

Heating and re-sculpting the ski jump gave ozmatt a working valve again.




It was funny: ozmatt was very doubtful the repair would hold up any longer than enough time to source a replacement valve. But that was April, and I don't think I ever saw a followup where he later replaced the valve or where the repair failed. I think it may hold up a good long time.

I don't think ski jump carve-out is really a common failure for these. In ozmatt's case, it happened during a sustained high-load drive on an already very (40 ℃) hot day; apparently a perfect storm where the valve's metal bits got hot enough to carve through the rotor material.

Probably nothing like that going on in grom's case. I just wouldn't want to leave other readers afraid to open the thing; as long as you have a tool for the stubborn Phillips screws, it's an easy inspection to make.

Threads are forever on PriusChat, so usually the reason for correcting something is not to pick on the person who said it, but to make sure future readers don't end up getting the idea there's a solenoid there, or that removing the stator lets the magic out.

 

I still think that there may be an obstruction in one of the passages of the intake or maybe even a crack in the intake. 35% glass filled PA6-6 nylon is tough but not unbreakable.

 

It's got to one minor thing that is causing your issue. The problem is solved by finding it.

 

Holy...did anyone notice the shortwave highest value? On a Gen 2, anything less than 4.99v means you're losing insulation value on the HV system and heading for a P0AA6 fault. This would prevent the car from going to ready/starting unless the 12v battery was disconnected to clear codes (or codes are cleared)

This car is at 1.5ish? Are the trigger values different for a Gen 3? Think I read somewhere that the Gen 3s were a bit different, but I just don't remember exactly.

And if the first code is for MAF out of range, has there been thought of digging into that? Seems the obvious path, but maybe I'm missing something?

Check engine light came on this morning-P0101 | PriusChat

 

I don't think grom damaged the MAF sensor or installed it backwards, if that is all possible.

 

Shortwave highest value
Page 2 line item 16 in your photos

On a Gen 2, this is a measure of the insulation/isolation of the HV system from the chassis of the car. It uses a range of 0-5v, with 5v being perfection. 4.99 is pretty much the standard value for a car in normal condition. I think somewhere around 2.8v triggers the P0AA6. This is a single trigger fault in a Gen 2 and although it will allow the car to continue to drive after being triggered, it remains in the ecu and will then prevent the car from going ready again once the car is turned off. The only way around it is to fix the fault or clear the code. If just clearing the code, it will usually trigger again soon, leading to a frequent circle of clearing codes so the car can be put in ready.

Keep in mind, I don't think the Gen 3 is identical to the Gen 2 in regard to the P0AA6 and it's trigger point or protective functions. Perhaps it's more just a troubleshooting indication. But, looking at the variation of the readings, from 1.25 to 1.5ish, there is something going on. It should be rock steady, not jumping around.

 

That's another reason I use an HPS intake with a K&N filter.


The MAF sensor is after the filter. The filter is totally enclosed to keep out rodents. Removing the OEM filter box provides space for close mounting of the oil catch can.

 

Each line item in the freeze frame data has 5 data points to the right. The five data points for the Shortwave Highest Value range from 1.5 to 1.25, with most ~1.5. Slang = 1.5 ish

 

Although my 2012 Prius v has only 26k miles on it, if the spare parts are not really expensive like the engine and inverter water pumps and the thermostat, I like to keep them readily available as spares that I can put in in less than an hour, rather than have the car towed to the dealer and maybe have them need to keep the car overnight and requiring me to find transportation to pick it up in one day or more.

If I can find used low mileage used parts like the fuel pump, I purchase them, too off of eBay. I even have one of those Prius v big orange HV battery cables. Most wrecking yards are apparently selling them for their high copper content. If the dealer has to get one, it might have to be back ordered from Japan for $1,200 or more.

Since the Prius v has been discontinued, the longer I wait to get used parts, the condition is degraded by use and wear.

Like a spare tire or fire extinguisher, it give me peace of mind that I can take car of a failure in a couple of hours instead of days at minimum cost.

Even if I never use these parts, their resale value on eBay is about what I paid for them.

 

"short wave" is a funny translated term. It will make most native English speakers think of a radio frequency band where you can listen to broadcasts from Romania.

What got translated from the Japanese here is just a "wave" that is used to test the high-voltage wiring for a "short".

The battery is supplying high voltage DC, 200 to nearly 300 volts. That whole system needs to be kept isolated from the car body and all of the 12 volt normal car wiring. The battery ECU needs to constantly monitor to make sure that isolation doesn't break down.

How does it monitor? Well, on top of the hundreds of volts of DC from the battery, it adds a small recognizable AC waveform:



Then it listens for any sign of that "short" "wave" turning up on the car body or in the 12 volt wiring.

According to a (possibly incomplete) Gen 3 repair manual going around, the "highest val" should be at least 4 volts, if in READY mode for at least 2 minutes and when the "voltage before boosting" and "voltage after boosting" are equal.

Yes, freeze frames from the codes set by the ECM would be useful, since the P0A0F is just another ECU saying "huh? engine won't start." P0A0F-204 is essentially an echo of the ECM saying P3190. It could be helpful to see what the ECM was seeing when it said that.