Why it's NOT smart to block your _PCV_ (edited) gas path

[Qman]

OK, OK, OK!!!!!

 

Geez, what a brouhaha!

 

I admit...I am the one who told Hank that a blocked EGR might be part of reason that he's using a really big chunk of oil.

 

I meant...PCV. Sorry, I was caught during a really busy Friday at the end of a long, hectic week.

 

PCV, EGR, ASV, LSD (which can have more than one meaning), VVT, DOHC SOHC. Doesn't anybody spell anything out anymore?

 

EGR may be "older" school technology, but it does work to reduce emissions. A bad PCV can cause oil rings to seize in the pistons. If you have a SPFI engine, the retrofit kit from the dealer is a good idea.

 

Or, the engine's just worn out...period.

 

Sorry, gentlemen. As Rick (aka Yoda) would say, "I'm talking out my ______".

Chalk it up to a long week.

 

Emily

http://www.ccrengines.com

 

Now, that makes complete sense. Don't worry Emily, everyone forgets which end their vocal cords are sometimes.

 

(Listen for the phone tomorrow. I have a question for you or Rick or ...)

 

Ken

[NorthWet]

Emily, to keep another long debate going, is there any way to tell the interference status of the EJ22 engine from the outside...

Hi, Jack!!!

 

 

 

 

 

 

Emily, I lived in the world of computers where nearly everything was TLAs (Three Letter Acronyms), and those that weren't were FLATs (Four Letter Acronyms, Too). Nothing is worse than sitting in a group of computer geeks that don't speak English with each other...

 

...well, I guess having to watch a chick-flick IS worse.

[edrach]

I love this! The thread that will not die. TTTWND!

Hi, Jack!!!

 

 

 

 

 

 

Emily, I lived in the world of computers where nearly everything was TLAs (Three Letter Acronyms), and those that weren't were FLATs (Four Letter Acronyms, Too). Nothing is worse than sitting in a group of computer geeks that don't speak English with each other...

 

...well, I guess having to watch a chick-flick IS worse.

[naru]

I think the original statement about not disabling an existing EGR stands up well for the following reasons:

 

Fuel efficiency mode

 

EGR has been used to increase fuel efficiency on many cars since the mid-1980s. During steady throttle cruise conditions, EGR

is used to reduce throttling losses. Throttling losses are energy that is used to create intake manifold vacuum and overcome the

intake restriction of the throttle. It takes significant horsepower to create the intake manifold vacuum that occurs under cruise

conditions.

 

During light-load cruise conditions, the EGR valve is gradually opened much more than is necessary for N[O.sub.X] emission

control. The open EGR valve reduces intake vacuum and replaces some intake airflow with EGR flow. The reduced intake

airflow reduces engine power, but the throttle is gradually opened to replace the lost airflow. Either the cruise control or the

driver does the throttle opening.

 

Because the EGR valve is opened very gradually, the driver doesn't even notice that he is opening the throttle to maintain

speed. The end result is intake airflow and, therefore, the fuel flow are both slightly reduced, but intake manifold vacuum and

throttle losses are significantly reduced. The benefit is reduced fuel consumption under freeway conditions. This EGR based fuel

efficiency mode is common on EGR equipped vehicles built during and after the mid-1980s.

 

Ignition advance

 

EGR flow can be used to allow increased ignition timing advance. That means the computer strategies used to control ignition

timing are heavily influenced by EGR.

 

As EGR flow increases, ignition timing is automatically advanced. Anytime EGR is reduced, ignition timing is automatically

retarded. This response seems to be especially strong and quick on OBD II vehicles. It is so effective that disabling EGR will

rarely result in a N[O.sub.X] emission failure in loaded mode emission tests. But, disabled EGR valves will usually result in

increased fuel consumption and reduced power because of the impact on ignition advance.

 

Combustion chamber temperatures

 

EGR reduces N[O.sub.X] formation by reducing combustion temperatures. The exhaust gases that are recirculated slow the

combustion process and reduce peak temperatures. Modern engines that use EGR systems are designed to perform very well

with the slower combustion that EGR causes.

 

When the EGR system on one of these engines is disabled, combustion chamber temperatures can rise dramatically and actually

melt components. The advanced computer-controlled systems on newer cars prevent this from happening, but it still occurs on

many older cars.

[PoorManzImpreza]

May I mention that I've never even SEEN a subaru engine outside my haynes manual and fsm that even had EGR? Even my ea82t engine w/ MPFI has no EGR provisions..so umm def not a requirement at all; total emissions control device..

 

We should all be forgiven for typos, even when they lead to debates like this..

[naru]

May I mention that I've never even SEEN a subaru engine outside my haynes manual and fsm that even had EGR? Even my ea82t engine w/ MPFI has no EGR provisions..so umm def not a requirement at all; total emissions control device..

 

We should all be forgiven for typos, even when they lead to debates like this..

 

 

Did you miss the point about throttling losses?

That relates directly to engine efficiency not emission control.

 

Who cares what you`ve SEEN?What does that have to do w/anything?

[MudisFun]

Egr, it's all about heat.

 

To keep the amount of nox down, the bad stuff out the tail pipe, a little bit of ash is thrown on the fire. I don't remember the exact figure but nox can be made at only a crazy high combustion temp, reburning exhaust is about emissions, nothing else.

 

From what I understand you can get more power without egr but you will lose the smother burn.

[Qman]

Did you miss the point about throttling losses?

That relates directly to engine efficiency not emission control.

 

Who cares what you`ve SEEN?What does that have to do w/anything?

 

It has everything to do with an opinion. Just like the one you have just shown. Next time try to rephrase it in a way that isn't attacking.

 

His point being that the EGR system on a Subaru is/isn't neccessary to have the engine run just fine. There are three variations of the EA82. Of those three one doesn't use a valve and the other two have them depending on original sale location.

[PoorManzImpreza]

*sigh*..Naru I meant no offence to your comments, and take none from yours..afterall this is USMB not NASIOC..

What I was simply pointing out is that Subaru only equiped vehicles with EGR when they had to reduce emissions..By that I neither confirmed nor denied whether it could improve or not; throttling losses, NOx emissions etc..All I implied was that since I had not seen such a subaru, be it ea63, ea71, ea81, ea82, ea82T, ej16 MPFI, ej18 carbed, ej18 spfi, ej22, ej22T, ej20g, ej207 powered, nor any JDM import, that was equiped with EGR where I live in Barbados and that we have no emissions restrictions whatsoever, that the system might just have only been installed as an emissions control device in areas where emissions control is an issue..I'll have a lawyer review my comments so as not to offend those with feather-light sensibilities

[WoodsWagon]

the EGR system is purely for lowering NOx emissions.

It works by reintroducing the inert exhaust gas back into the combustion chamber to lower peak combustion temperatures, where NOx are formed.

 

Misconceptions range from thinking that it is "reburning" the exhaust gas to make it cleaner. It can't burn to start with, so it can't reburn and the amount to reburn to clean up the exhaust would make the engine stall. I can't tell how many times experienced mechanics have stated the reburning Croc'o'sht.

Improves gas milage. Bullhooy! By reducing the amount of combustable mixture in the cylinders, you are lowering the power output of the engine. Thus, you open the throttle more to let more in increasing the power to what you need to cruise. Gas milage stays the same because the same overall amount of fuel/air mix is being burnt.

 

Removing the system will not kill the engine. Just make sure both ends of the system are sealed off well. The engine will not run rich or lean because of the system because the gasses are inert to start with and only take up volume, reducing the amount of metered and mixed air/fuel. When it is removed, that volume will be replaced by an equal amount of METERED and MIXED air/fuel. It will be mixed properly, and may lead to a power gain because of more A/FM in the cylinder. But not that much.

 

The system is a matter of choice. Sacrafice a bit of power to lower NOx emmisions, which are a major ingredient to smog, or strip the system in the name of simplicity and dinky power gains and FUBAR the air we have to breath. Its up to you.

 

My personal opinion is that the CO/HC convertor should be ditched and the lean/rich cycling of the injectors should be set to a linear steady mix. The lean/rich cycling seen by the O2 sensor is mostly just to feed the catalyst and keep it up to temp, it seems. I'm not sure if the cats are really necesarry anymore or just a holdover from simpler days.

[Hank Roberts]

Whew. What a long strange thread it's been ...

 

Thanks for chiming in, Emily (ccrinc); I edited the thread title and first post so people are waved off early if they find this thread later on.

 

You all ought to be getting my old engine back from the Berkeley mechanic next week sometime -- please let us all know what you find, when you take it apart? I think it'd be a fitting cap to this thread. I know the PCV system on that engine had been clogged for a while, as well as the ports for the EGR filled up with hard carbon.

 

And I'm really curious to know how it looks inside, remembering it'd been taken apart and the gaskets replaced (the Berkeley mechanic's attempt to stop it burning oil, which failed) -- that was done j a few hundred miles before got sent back to you as a core return. I hope you can tell us what condition the rings were in, and where the oil was going. Anything you find, feel free, please, to post.

 

(Reminder, it was a used (supposedly imported Japanese) engine put in perhaps 30,000 miles ago, by the previous owner's shadetree mechanic --- no guarantee of its prior history. It had been run with the engine light on most of the previous year, both the EGR system and the PCV system at least intermittently blocked, and who knows what else. It supposedly still had good consistent compression on all cylinders, too (sigh).)

But was using half a quart of oil in 300 miles there at the end, in freeway driving.

[Hank Roberts]

Oh, and, um, Emily -- you wrote:

 

> If you have a SPFI engine, the retrofit kit from the dealer is a good idea.

 

Is that on the rebuilt SPFI that's coming here from you? Or something I need to track down?