Need help with Custom PIDs for Gen 3 Electric Water Pump (21D7) in Torque Pro

Torque might not have that PID, but its a smart one to have. Basically anything that can monitor the details of the electricity going to that pump would be helpful.

I know CarScanner Elm app does better at communicating with all the system and Torque is a very old system that doesn't get updated much (if at all). Also the Autel AP200 OBD2 reader does complete diagnostics equivalent to Toyota Techstream.

 

The raw values are high because the equation is missing the 0.25 multiplier /
Use ((D*256)+E)/4 for the correct RPM /

At 16 years old, that pump is at the end of its service life /
A new pump is cheap insurance; a warped head or a replacement engine is not /
Do not risk the car to save a little money /
Just replace it with an OEM unit /

 

ISTR some discussion of this before, and looking up the big PriusChat spreadsheet of gen 3 PIDs, and seeing none for the engine water pump. An odd thing to be missing, but the scan tool vendors like Autel license all of that data from Toyota, and the rest of us (and the scan tools that don't license the data) have to figure out the PIDs by reverse engineering, and it might be that nobody has gotten around to those couple PIDs yet.

 

It's also history of the app itself... During the early days of Gen2 Prius the Torque app was a really big deal and lots priuschat-like enthusiasm was going on among the app users. But then, by the time Gen3 users were getting started Torque lost popularity and folks started using Hybrid Assistant / Reporter and Dr. Prius App, so there wasn't as much of a Prius community on Torque to build more PIDs.

As in, the 2004-2009 era of the Prius Community was a golden era in terms of technological excitement about Prius when their was lots of crowd-sourced innovation, as well as start ups selling plugin hybrid kits.

 

I assume what you mean here is the exhaust heat exchanger, which is the third 'lump' in the gen 3 exhaust pipe counting from the engine end, coming after both catalytic converters and before the resonator. I assume you chemically cleaned the coolant path through that exchanger. Would that be right?

I have also heard of chemical treatments for actually cleaning catalytic converters, such as to resolve P0401 codes, but I assume that is not what you did, is it?

You did a great deal of other work, but happily, your thorough approach did lead you eventually to the cause of the problem.

I wish I could have made this suggestion before you did all of that work, but anyway: the gen 3 Prius has two coolant temperature sensors, and either one can light the overheat warning. One is in the cylinder head and reads the temperature of coolant exiting the engine, and the other is in a coolant hose near the wiper cowl, and reads the temperature of coolant coming up from the exhaust heat exchanger. Techstream or another suitably-capable scan tool can show you both readings. If the high reading is coming from the EHRS sensor, a stuck exhaust flow valve is a very likely explanation.

 

Your car is a gen 3, is it not? That drawing isn't the clearest picture of the gen 3 exhaust pipe; this illustration shows more clearly what it looks like.



(Of course, in a real car, it isn't polished and shiny, and doesn't have a sign reading "Exhaust Heat Recirculation System" stuck on the heat exchanger. There also may be some heat shields around it that were left off for display.)

In the display picture, you can clearly see the car's two catalytic converters (the first two bulges, counting from the left), and next the exhaust heat exchanger (the third bulge), which is not a catalytic converter, but has coolant pipes attached, and finally the resonator/sub-muffler (the fourth bulge), which is also not a catalytic converter.

I am not sure what you cleaned "with the help of catalytic cleaner". That is more often something people attempt when there is a trouble code for degradation of the catalytic converter.

For a coolant overheating issue, I would have my attention foremost on the path followed by the coolant—which does pass through the heat exchanger, but does not involve either catalytic converter.

Following the coolant path, of course, takes you to the faulty valve that you found, which is not an uncommon failure item, and does lead to the overheating you experienced.

Using the information in ➡this post⬅ (and the first link within it), you will know as much about it as I do, which isn't everything.

 

The entire polished part is not the EHRS, it is the front exhaust pipe assembly. It consists of two catalytic converters, followed by the EHRS exchanger, followed by a resonator (or sub-muffler), all welded along a stainless-steel pipe.

So when Cataclean is poured in the front end, it does flow through the first and second catalytic converters (which it is intended to clean), and also through the EHRS exchanger (which it probably has little effect on) and through the resonator and out the back end of the pipe.

The usual reason for trying Cataclean would be a P0401 code, indicating that the catalytic converter effectiveness has been reduced by chemical fouling of the catalyst honeycomb. It is not a likely suspect in coolant overheating.

The thermostatic valve of the EHRS exchanger is indeed a known suspect for coolant overheating, as you found.

Yes, that's what was happening. The overheat warning on the dash was being triggered by the EHRS temperature sensor reading, while your OBD2 scanner was only showing you the cylinder head temperature reading.

 

As Chapman noted, we have been down this road before with a stuck Exhaust Heat Recirc System (EHRS) Valve.

The "Car Scanner" app can display both temperature sensors without modification and can generate graphs. Techstream has two but they are both called Coolant Temperature, one in the Combination Meter ecu, the other in the Engine ecu.

Two temperature sensors from Car Scanner app (graph configured from default data scan)


Car Scanner Graphical Trend with Normal EHRS thermostat followed by stuck closed thermostat. Normal Exhaust Heat 7C0 sensor is almost always lower than Engine_Block 7C4 sensor
The stuck closed graph was on a vehicle experiencing occasional high load temperature warning lights (>248f) while the block temperature remained normal.

A no cost solution employed by the owner was to force the EHRS open with a small piece of metal shown with pink highlight on end

 

Why the hell has @Mendel Leisk or you never mentioned this valve before? Seems ridiculous with the amount of hot engines blowing head gaskets in Gen3 that no one has ever documented how to do regular maintenance on this component to prevent it from failing? Why would it never be a point of emphasis? Does anyone have a legitimate link on how to clean and inspect this system?

 

no

 

I have several threads* mentioning the subject including one with the graphs shown above.

Keys to understanding the situation is there are two separate coolant temp sensors, one of which is immediately downstream of the EHRS system output. The other is on the block coolant output feeding the radiator.



The stuck valve does not overheat the engine. It is a relatively minor volume feeding into the egr cooler. Even in a normally function EHRS system, coolant flow always continues through it.

BUT the EHRS system's thermostatic valve moves to allow a straight through exhaust path as illustrated in the smaller attachment above. It does not control coolant flow.

The major engine to radiator flow is not impacted. Which is why the op mentioned the engine block sensor never overheated.

Net result of a stuck EHRS valve? Exhaust is forced through more of the heat exchanger warming it up enough to trip the temperature sensor on the dash. On very high load conditions. Without overheating the engine.

* When I was moderator of a large car forum, I or the op would have retitled certain threads to make future searches easier. No editing restrictions. I would also ensure sales and disruptive dialog were cleaned up. Unfortunately the loudest voices here sometimes prevail to the detriment of future users.

 

If I remember right, Priuscamper blocks anyone that pushes back on his rhetoric. Which might mean he never sees rjparker's content on subjects like this.

 

Wrong again...