Swapping in a Gen 4 Prius' 2ZR Engine into the Prius v

Well I did it again in record time 9hrs engine out swap damper engine back in, everything went well. I did solve the issue by the way.
I agree gen 3 springs are not strong enough is why gen 4 has only 3 beefy springs. I think this may save me in the future from broken spring which I feel would hit sooner or later. It was worth it to not feel the micro loss of power as the springs bounce back and catch up.

 

This is the springs in the damper?

 

New issue. Now I have seen many posts on EGR issue. I have a 2010 prius with gen 4 engine and gen 3 EGR circuit.
Can someone give me the quick and dirty on the EGR? now is it the cause of the head gasket issue or not?
I know if you unplug it bad things happen but car runs ok with anomalies and you get clean intake and not so dirty valves.
to pass smog just plug it back in. Don't worry I will plant some trees. Now I think mine is sticking as the system is clean ( EGR circuit) and I have not used it much since engine swap only for testing.
1.so my questions are is the EGR gas the cause of head gasket?
2. can you lube the valve as I think mine is sticking. I tried wd40 already.

 

So are you saying when you plug in the egr the code does not go away or you have a drivability issue? What exactly is wrong?

Egr causing a head gasket is the Prius debate of the ages. It used to be hypermiling. Now its why has my engine blown a head gasket? First lets assume no overheating events, knock sensor failures or loose head bolts are the primary cause. Those are the common hg issues with any engine.

Personally I think it is the classic "what came first, the chicken or the egg?" Several of us including some Toyota mechanics believe oil burning came first, bad pcv design came second and severe carbon buildup with clogging resulted. Ultimately carbon increases cylinder pressures, preignition occurs (even though the knock sensor responds), uneven egr flows happen and liquid slugging from the intake via the pcv adds stress. All are likely to have contributed to gen3 hg failure.

Its interesting but not definitive that most Prius hg fails are usually 2010-2014 and not the 2015-17 gen3s. Others suspect constant thermal cycling of the engine plays a role, perhaps even impacting head bolts and allowing degradation of the head gasket.

But many, especially on Priuscat, blame the egr system as the root cause, particularly the egr cooler size and upstream location. When you look at a complete gen4 system you see major egr changes, cylinder cooling redesigns, intake mods, etc. You should have good gen4 pistons, rings, consistent cylinder wall cooling combined with a gen3 egr and most of the other gen3 features. I would run the gen3 egr for emissions and for its designed cruising speed combustion chamber cooling. Primarily because your controls were made for an egr to be in the mix.

One thing that is not discussed often is the fact these early gen3 head gaskets easily made 100k miles, most last well over 150k miles. Which means a non-oilburning clean egr engine with limited blowby to clog things and fill the intake with liquid should have little chance of a sudden hg failure. Which in my book is enough reason to just refresh a gen3 with a good rebuild.

Now that you are a fledgling journeyman mechanic, cleaning the egr every 50k should be a walk in the park. Finally, I have to pull out my Johnny engine swap meme.

 

only issue is when egr is connected it misfire. random all cylinders. Very minor. Now egr gases to me if none are introduced then you dont get any extra heat since all that goes in is fresh air and fuel both of which are cooler than egr gas. I think my egr is just binding due to carbon buildup in the stem of the valve so I think some high temp grease should solve that or is the a best practice for this issue.

 

Egr theory is that mixing in exhaust gas at cruising speeds reduces the cylinder temperatures by diluting the air fuel mixture. So when you don't have it the gasses in the combustion chamber can get hotter, sometimes by 150c. The computers think egr is happening and adjust for it providing the optimum emissions and improved mpg. Or it defaults to some reduced performance setting.

The egr should be partially or entirely closed at idle, low speed and wide open throttle. The computers expect this as well. Stuck full open when it should be closed could cause misfires. Using a gen4 egr could also be a problem.

In any case, you don't want misfires or preignition especially under load.
How Exhaust Gas Recirculation (EGR) system works

 

I see, well at idle the car random misfires with gen 3 egr connected and operating properly "no codes". When I unplug it the misfire stops and the CEL turns on with the code off EGR of P0403 of course as it is disconnected.

 

If all you do is unplug it and the egr valve closes and stops the problem I doubt it is stuck. Still its worth cleaning by primarily removing the carbon. Perhaps it needs to be left connected and the ecu's 12v reset so the system recalibrates. Otherwise the egr valve could be defective, or a wiring or sensor problem is causing the egr to open too much. The map sensor is primary but others may play a role. See the egr link above.

 

As rjparker points out, that's a bit backwards. Yes, exhaust gases are hot compared to intake air, but they are nothing compared to the peak temperatures reached inside the cylinder on the power stroke, and they don't burn, so they keep those peak temperatures lower. That, plus the ability to dial back power with less throttling loss, is the whole reason EGR exists.

That said, they also don't have as large an effect on the temperature of the engine as sometimes gets made out. The same amount of fuel, efficiently burned, is going to be about the same amount of heat on every stroke, and the EGR only influences whether that all happens in the first 20° crank angle or spread out over like the first 80°. The macro heating of the engine has a cooling system and thermostat to control it. The responsibility of the EGR is the peak temperature a burning ball of gas hits for a matter of milliseconds, once every power stroke.

Have you ever taken the valve out, left it electrically plugged in, and used Techstream to request different step positions and watch it move? Or done the same on a bench?

It's well and good to have an idea what you think is happening, but sometimes progress stays elusive until you start planning ways to find out whether what you think is happening is what's happening.

 

Cant you just clean off the carbon buildup on the stem of the EGR valve?

A YouTube video posted uses PB blaster penetrating oil as lubricant for the EGR solenoid stem.

Posted via the PriusChat mobile app.

 

very valid points. Im not good with the tech stream but I have taken it out and aplied voltage and seen it pop up and down on all the pins so I suspect its binding I will give it another clean. that being said when putting it back together do you just put the magnet back on or do you screw it down?

 

It's a stepper motor. Have you read up on how to control a stepper motor on a test bench?



If you are just applying voltage to pins of the valve, a little popping up and down is all you will ever see it do. That's normal. To make a stepper motor turn, you have to get the sequencing right.

 

EGR Valves can and do wear out, on the Insight you would tear them apart clean and rebuild , the contacts and wipers would usually need work

 

No contacts or wipers on this valve; it's a stepper motor and positioned by dead reckoning.

An '84 Ford I used to have did have a potentiometer EGR position sensor, and yeah, that was nothing but recurring aggravation.

 

I'd like to know this as well, I just cleaned a spare EGR valve and took it apart while cleaning it up. It seems that you have to screw it down to assemble it back together.

I'm thinking that the spare I have is off a car with much more miles on it than my car, judging by how much the EGR cooler it was attached to was clogged.

I'm thinking of putting this cleaned EGR valve onto my car, but swapping my solenoid/stepper motor on it when I get around to the EGR cooler swap.

Thoughts?

Posted via the PriusChat mobile app.

 

You kind of have to wind the rotor back down onto the stem before you can fit the stator back on.

Plus, if the springs are doing their job, the rotor will kind of want to spin back up a little. You can't hold it there forever, eventually need your fingers out of the way to push the stator the rest of the way on.

What that means is probably the rotor will spin a little way back up, just as you are pushing the stator the last bit of the way on. So you will end up pushing the valve slightly open. Once you've tightened both screws, you can turn the valve over and see that the pintle isn't completely closed. It's sticking out by a few mm.

That's doing you a favor, really, because it gives you an easy way to check that you reassembled the thing without any binding. Put your thumbs on the slightly open pintle and just push it all the way closed. It should feel smooth and whirry and you'll hear the rotor whirring inside as it moves, and there's your confirmation that you didn't get anything wedged up in reassembly.

 

Yup this was it. spring first then screw magnet back in and then the cap "key" is to lock the cap as in it should stay by itself then the screw this guarantees you have the right fit. if you don't do it like this there will be all kinds of shenanigans.

 

Here is a video I found where a guy does it perfect.

 

... as perfect as it gets when he spends the first ten minutes saying a UNF #10-32 screw is the right replacement if you happen to damage the metric M5 0.8 that came in your Japanese Toyota. Somebody caught that in the youtube comments too. Not such a promising start ....

It basically shows him getting it apart and back together without disaster even with using the wrong screws. That should be encouraging to anybody thinking it might be too hard to do.

He seems to have convinced himself that the stator somehow fails often, despite being nothing but some coiled wire on a metal core potted in plastic. He has replaced it three times to solve some problem. Leaves me wondering what problem he's really having, and what's really behind it.

 

Yea not sure but he put it in right which confirmed what you said. ITs almost like we need a best practices manual.