Unplug EGR Valve

Car has developed the clogged egr knock. I've ordered a new cooler so I can have two and always have a clean one on the shelf. But I decided to just unplug the egr valve (its getting the knock at some times from insufficient air flow I assume, but no cell) and the knock completely disappeared. Threw my first check engine light in 12 years and 193k miles with the car. This seems to be a better solution than shifting to neutral every time the car starts to hesitate. Car drives like new again and per scan Guage is still getting the same gas mileage (52-58) Somebody tell me I'm a bad person for doing this.

 

The thinking with this is: if you unplug the valve it will not be exposed to the lower than expected egr condition when the valve is running and open and will revert to the failed egr valve condition when the system sees Xv going into the valve and 0v coming out of the valve. Seems like this car doesn't have sensitive enough knock sensors and egr flow sensors to begin with compared to my Ford Ranger that would knock immediately under low egr and throw a code.

 

Update: After clearing up the knock with the sensor and ordering a new cooler, I decided to get a head gasket testing kit and the block tester fluid. Harbor freight were the only ones that carried it in store same day.
Tested the kit out on a 4runner I know of with a blown head gasket and the fluid turned greenish yellow. Tested this kit on the Prius and the fluid stayed dark blue.
Scotty Kilmer has a video on how to do the test: "How to test a blown head gasket in your car"

So Prius will live to see another day!

 

Tester doesn't pull up fluid. Its sniffing for exhaust in the cooling system. If you pull fluid into the tester (possible on other cars) the test fluid is ruined.

When the cooler comes in I will install it and clean the manifold. Get the egr going again and reassess.

To add the car never threw a cel. I made it throw one when I unplugged the egr valve. For clarity*

 

Cooler came in. Install coming up. Put ~1000 miles on the Prius since unplugging the egr valve and still getting ~48mpg highway and ~54mpg average on my work commute. Checked coolant and it still hasn't moved and car hasn't blown up. I really wonder what the benefit of putting the new cooler back in will be? If mpg doesn't change I may just leave the egr valve unplugged forever.

 

By knock I don't mean rod knock. I just mean this butt sensor can feel the misfire. Unfortunately the car gave me no check engine lights. Replaced the cooler today. It was 100% plugged. Couldn't see through it or blow through it. Egr valve was caked up so I cleaned it. Cleaned the little passages in the intake with weed eater line and brake cleaner. So it's all clean. Reassembled and no improvement with egr valve electrical connector connected. As soon as I unplugged the sensor again it drives smooth again. So there's no visualor audible knocking I can just feel the extra nvh. Hmm....
So yes I'm still driving the car with the ghetto egr delete. I'm assuming the egr valve might be bad so I need to test that.

 

Local dealer said there are tsbs out for the issue. He said that it may be accompanied by a check engine light but that's not always the case. Due to excess carbon build up at the valve assembly, the valve will stick causing the engine RPM to fluctuate. He said since they don't clean things normally they replace the intake manifold and egr valve assembly. But he said since I've already cleaned the intake manifold passages, replaced cooler, and valve I could try replacing cleaned the valve. He said the part number to fix the issue is new and requires a software update to the car to use. He did note he is not sure why the new valve requires a software update.
Should I get the old valve from an Ebay Toyota dealer that still has it? ($199) or get the new valve and update? He said since I've already done the cleaning I can install it and bring it up here and they will just do the update. He said since the cars already running with the egr unplugged that will work but he wasn't allowed to make any recommendations on anything tampering with the emissions equipment. Lol
Total cost of this is $438.
Price is high but I'm interesting what this update to the cars computer will do. Also comes with an emissions modification sticker to put on the car.

 

It is slightly different. Doesn't look significant though so it may be electrical changes that have to be measured.

 

I can measure it if you get a list of things you want. Also this valve is Aisan.

 

I've read a lot of threads today about people chasing these issues. I'm not extremely invested in spending a lot of time and money on this vehicle. At the end of the day it looks to be another car with a targeted obsolescence compared to the 90s Toyotas I know that will go to 500k. May just do what I did with my $500 civic. Drive it until it needs to be repaired and then throw it to the next owner. That car had a 4 cylinder misfire above 75% Load on the scanguage with misfire codes and still did another 35,000 miles. I think I got my monies worth and the next owner still drove it home without a trailer.
I will ponder which valve to go with (and I might ultrasonic clean the manifold with our industrial one at work) and if that doesn't work it will live out its days without EGR (albeit with a p0403 running in safe mode (?) ). If the head gasket starts going on to the next guy or I will sell the exhaust and battery and sell the body to the junkyard. Its been a good car. But it sounds like it will turn into a lemon soon.

 

Welp. Decided not to worry about it. I will now be the product tester for the egr delete on the Prius. Considering the mpg is still doing good and the motor runs clear and all fluids are fine I decided I am not worried about the cel on a dinged up 12 year old car.

We have a lot of guys testing a lot of theories on these cars so here is another one. Maybe this will help someone in the future. lol

I will try and chime back in on this if I notice anything good or bad and if or when the car blows up.

 

Update so far: oil consumption seems to be 1/4 of what it was. Last oil change over 3190 mi the car consumed 1.34 qt. ~2400mi/qt
Currently at 2700 mi and 79% of dot to dot (by my math I did measuring a photo) on the oil stick. I put in 4.4 quarts, so it looks like I'm missing ~0.33 qt. By guesstimation math thats about ~8200mi/qt. Will update after the holidays when I change the oil. Also, the oil is a lot cleaner.
*I'm kinda thrown off so I keep measuring it because I usually add oil by now andI haven't.
*Also, coolant is still stable and the engine is smooth with no funny business.

 

Last oil change:
3120 miles.
Burned 18oz.
0w-40 for both of these oil changes.
So burning a quart every 5500 miles now. I have swapped back to 0w-20 now. I think there was a cleaning effect either between the 3000 mile oil changes or the egr circuit being bypassed. But it seems to be getting better. 1000 miles into the 0w-20 change I have now and the oil is still covering the top dot when checked after sitting on a level surface. Going to attempt 4000 mile oil changes from now on. Around 189k-ish when the car started misfiring the car was consuming a quart every 1200ish miles and now I'm assuming i won't need to add oil between changes anymore. Hoping to achieve the level of my 225k mile sequoia which burned 2 oz of oil last 5500 mile oil change.
I did note that on the LS400 I am planning to buy a lot of those guys have the same issues with egr. Their fixes are the same. They say it is a functioning system that does need to be cleaned, but a lot of them prefer to delete or unplug the system and take the cel if you're in an area without smog.
One thing to note: I did unplug the battery with the egr unplugged and the car will high idle in neutral when the battery is reconnected indefinitely. Fix is to just plug the egr plug back in drive for a mile or two and then unplug it again with the battery connected the whole time and the car will go back to normal. I know unplugging the connectors with the 12v is bad but this is how I did it.