I've been reading up on PCV and EGR and want to get this out in the open. I'm still struggling with the concept of removing them. From what I read/understand, they're emissions control devices that make the engine operate less effectively.

Here's some information on the EGR:
http://www.misterfixit.com/egrvalve.htm

Here's some information on the PCV:
http://www.autoshop101.com/forms/h63.pdf

Particularly the quote about the PCV that I'm trying to figure out:

"The purpose of the Positive Crankvase Ventilation (PCV) system is to remove these harmful gases from the crankcase before damage occurs and combine them with the engine's normal air/fuel charge."

Couldn't we just dump the PCV into the "atmosphere" (see: catch can) and not put gases back into the intake charge? The supposed downside of this is the car runs leaner but seeing as our tC's run about 12-13:1 anyways thats not a bad thing. It may actually lean it closer to preferred (14.5-14.7).

Anyone have any input with experiences with bypassing the EGR and PCV?

 

Do it if you're boosted. Otherwise, it's not worth tampering with and making anything risk failing smog.

 

i'm in FL and it doesn't matter for me. main thing i'm trying to avoid is the carbon buildup and running richer than i should be.

I'm going to get the catch can for the PCV but what could I do for the EGR? Hack another catch can on there or what?

 

the PCV system is a tricky beast. Yes, dumping to atmosphere is a good option, but how are you going to get the gases to go into the catch can at all times. I'll point you to a link on honda-tech, which goes into a huge amt of details.

http://www.honda-tech.com/zerothread?id=1199935

for my setup on my honda, I'm lucky, as my block has two large ports that can be opened and used for crankcase ventiliation. the two ports are feed into my catchcan which has a filter on top (Moroso catchcan, its baffled, one of the few that are, you want it baffled). By having the duel ports, the pressure is releaved and is able to flow from one port to the other.

What i see most people do is run a hose from ther PCV valve to a catchcan, then that's it. well the PCV is a checkvalve. if boost is pressing on it, it wont open. So this is great for NA cars, as in stock form its PCV to intake manifold, always vacuum source. if you did this with boost, then any time in boost, PCV isn't being vented and your rings are getting more pressure built up under them rather than where it shoudl be on top of them.

this is why the dual port setup before a PCV setup works on hondas. What i now recommend people to do, is run the old school slash cut ventilation. PCV valve to hose to a slash pipe in the exhaust. The slash pipe is a metal small pipe that is welded into the exhaust at an angle with the outlet pointing towards the flow of the exhaust. Therefore the exhaust of the car causes a vacuum to pull out the crankcase gases.

the crankcase gases are basicly oil vapor, as when the rods are moving fast on teh crank, oil is slug off them creating a vapor in the air beneath the piston. this vapor causes pressure under the piston, basicly imagine pressing down on a balloon. if the balloon's gases are vented its harder to press down on a fully inflated balloon rather than a deflated one. the gases can build up and put strains on the pistons, the rings are what break due to thsi pressure from crankcase gases under them and from the combusion process above them. So that is why the PCV system is there, to releave that pressure. If you are boosted, it needs to be addressed or problems can happen.

On stock boosted cars, this is why you may see the PCV running to the intake before the turbo, as that always has vacuum, but if its pre-MAF, you can get oil on your MAF which will screw it up and you are still putting oil vapors in your intake air. Oil decreases the octane rating of your gas, thereby causing detonation.

 

so using a moroso catchcan to take from the PCV to the can and dumping into the exhaust is the ideal setup?

for now I'm NA....won't be for another year or so if I ever see boost

 

This is interesting. My friend ripped the EGR out of his focus and it has a bad idle now.

 

possibly running lean. has he had that checked out?

 

it has a bad idle, probably because he didn't block off the stock EGR stuff appropriately, ie i'm not sure if focus are MAF or MAP, but if MAF and if he created a vacuum leak, then it would idle like poo.

basicly i view the best as PCV to catch can which is baffled to exhaust slash

 

well i'm going to do the PCV catch can but i guess i'll just keep reading about the EGR fix

 

WOW.. i can;t believe what i have read here... here is the deal.. the PCV is there to remove harmful gases ..yes... but cause by oil..?? that the first i have ever heard this....... these gases are blow-by.. meaning, combustion gases that get by the rings.. these gases will mix with the oil if not ventilated and will cause oil brakedown.. do you wonder why oil turns black..? the pcv sucks these gases from inside the engines.. unforntunatly oil particles will get caught in the stream and get carried out with the gases.. that is where the catch can comes in..

NOW.. to the TC engine.. We have 2 pcv vents.. one on the rear left corner on the valve cover...( you can only see this if you remove the plactic cover..) which goes directly to the intake manifold... the other is the one on the front right corner... which goes to the intake duct... if you wanted to effectively use a catch can.. you would either have to use 2 catcht cans or find a way to use 1 can with both vents.. if you remove the pcv.. then be prepared to have dirtier oil.. but removing the pcv would/should not harm the engine persae...

ON EGR.. i have yet to find the EGR system on the TC.. from what i can tell we do not have one.. EGR=Exhaust Gas Recirculation...

 

i believe the valve on the left rear of the head is actually the EGR.. it removes the gases from the top of the head at the complete opposite side of the PCV and sends them into the intake manifold.

i'm going to do some looking in the FSM

 

i think this is one of the 2....

 

 

Matt im not sure that the rear left vent is EGR.. if it is considered a vent as im reading then it is still PCV... why it is called a valve is becuase maybe there is something to regulate the vacuum pulled.. especially since it is coming directly from the intake manifold..

i mean.. if you really want to get technical.. PCV is kind of an EGR since the gasses it is pulling are technically combustion gasses that have gotten by the rings... but most EGR systems pull directly from the exhaust track.. usually directly from the exhaust manifold... but it can be drawn from anywhere in the exhaust system..

 

from the first link i posted:

There are a zillion different types of EGR valves some of which work strictly on vacuum, and some which work on a combination of vacuum and pressure. Some have electronic controls, some have mechanical controls.


I would think the little valve thats on the first pic makes it function differently than the one on the right. too bad we don't have any Toyo mechanics on these forums.

 

I never said that PCV system was caused by oil, but if that oil vapor that is created from the rotating assembly moving and blowby gets ingested back into the engine you get detonation.

 

That is the PCV. If you take that hose off you will find oil residue in this hose, but if you pull off the hose on the right side of the valve cover, you will find no oil residue.

The hose on the right side isn't a PCV too, due to it not having threads, so that it can be screwed into the valve cover, like the one in the picture above. The tC doesn't have two PCV's.

The hose on the right side is just a breather, with no oil going through it, therefore no oil catch tank is needed, except for the PCV shown above .....

 

so what about the EGR?

 

The EGR valve is part of the intake and exhaust manifold system.

The EGR valve controls a small passageway between the intake and exhaust manifolds. When the valve opens, intake vacuum draws exhaust through the valve. This dilutes the incoming air/fuel mixture and has a quenching effect on combustion temperatures which keeps NOX within acceptable limits. As an added benefit, it also reduces the engine's octane requirements which lessens the danger of detonation (spark knock)......

The EGR valve consists of a poppet valve and a vacuum diaphragm. When vacuum is applied to the EGR valve diaphragm, it pulls the valve open allowing exhaust to pass from the exhaust manifold into the intake manifold. Some engines have "positive backpressure" EGR valves, while others have "negative backpressure" EGR valves. Both types contain a second diaphragm that modulates the action of the valve. This prevents the valve from opening unless there is a certain level of exhaust backpressure in the system. EGR valves are calibrated for specific engine applications. The wrong valve may flow too much or not enough exhaust and cause emission, driveability and detonation problems.

EGR valves do not normally require maintenance or replacement for preventative maintenance. But the valve can become clogged with carbon deposits that cause it to stick or prevent it from closing properly. Dirty EGR valves can sometimes be cleaned, but replacement is necessary if the valve is defective.

Some newer engines are so clean from a NOX emissions standpoint that no EGR valve is required.

Hope this helps you understand a liitle better.....

 

awesome. thanks a bunch.

i'm guessing there are no benefits from modifying the EGR then? (i.e. no carbon build up, cleaner intake charge)

or would it just take a chance of screwing up the engine?