What is the source of the exhaust for the EGR? is it the split air pipe? The exhaust manifold? Where does the gas go into the intake manifold? Factory shop manual information is cursory at best.

Thanks,
Eric

 

http://autorepair.about.com/library/..._SKD&terms=egr Just put a piece of vac hose on yours and suck on the line. If it holds a vac, its most likely good. If not, it sucks and is no good. Cost about 125 bucks new. I can pass emissions at will without mine, although I did get foolish one day and buy one. Only God knows why. I don't.

 

The exhuast comes from the intake manifold-

You'd understand if you took it apart-

 

Last time I looked the exaust gas came from the single half inch hole(the only one of the two that is not blocked by the exaust gasket) located below the rear exaust port, entered the intermediate housing, traveled up the intermediate housing to the egr, and if the egr was open, fed the exaust gas from one side of the egr valve to the other. Thats what I remember about the path of the exaust gas. Maybe I need to look again tomorrow morning. This in reference to DYRE post. I know I could be wrong again. Maybe. Refering to a 87n/a here. EDIT: Just looked. Yes, from the 1/2 inch inboard hole under the rear exaust port, thru an internal passage up the intermediate housing to the egr valve. Egr open and ports that exaust gas to two approx 3/8 inch holes, one of which goes to the intake passage for the front rotor housing and the other hole leads to the intake passage for the rear rotor housing. It helps to be able to look at an intermediate housing and the passages. The intermediate housing contains the intake passages for the front and rear rotor housings with the egr mounted on top of it. Talking 87na here. Not turbo.

 

I think thats right.

But it makes it was through the intake manifold right before it gets to the valve (just a little 90* turn in a passage) where it meets the EGR.
It doesnt accually mix with the intake flow until after the EGR where its controlled and released by the EGR.

At least thats the way i understood it when i had the whole thing apart. Becuase doesnt the manifold have two holes where the EGR bolts up. On side is for the exhuast coming in. The other is where its released into the accuall intake track.

 

I wish we had a engine apart in front of us. I know where you are coming from and why the confusion. There is a path from the rotor housings that feeds back to the intake manifold, but that is for port air from the acv. The rotor housings have sort of triangular pockets at the bottom on either side(either side meaning front and rear sides, on the right side of the engine). The rear pocket has two holes in it. One hole goes to the diffusers. The other to the exaust manifold(one of two 1/2 inch holes below the exaust port). This hole to the exaust manifold is blocked by the exaust gasket. Now the triangular pocket on the front side of the rear rotor housing has but one hole in it. That hole lead to the exaust manifold,and luckily there is a hole in the exaust gasket at that point to receive the exaust gasses. Well that gas from the exaust goes thru the triangular pocket, to another triangular pocket in the intermediate housing, travels thru a internal passage in the intermediate housing upwards to the egr valve. If the valve opens, exaust gas is fed into two approx 3/8 inch holes one of which lead to the intake passage for the front rotor and the other to the intake passage for the rear rotor housing. Bottom line is , that if one switches rotor housings I.E. front to rear, rear to front, these triangular passages will not allow the flow of port air TO the exaust but I think you still get egr exaust. Can't really explain any of this without having the housing in view and pointing out the passages and paths. Oh well.

 

HERE: http://www.mazdatrix.com/e6.htm Look at the exaust gasket, item E. See the half inch hole just below the large rear exaust port? That is the hole that feeds the egr valve thru a passge in the rear rotor housing, to the intermediate housing, up the internal passage in the intermediate housing to the top where there is an opening for the egr valve. Then from one side of the egr valve to a 3/8ths hole in the intermediate housing, down a passage to the intake passages for the rotor housings.
DYRE: I think we are talking two different things. I'm talking about the N/A engine where the egr is located on top of the intermediate housing and you are talking about a turbo engine where the egr is mounted on the backside of the intake manifold. Two different paths. Sorry about that. I couldn't tell what kind of car you had or what kind of car the poster had because it wasn't in either of your profiles. Yeah, on a tubo the path is like DYRE says. I have a turbo engine sitting on a bench and I refuse to take it apart to follow the path. humor.

 

Every side housing has a port next to the rotor housings exhaust port. some exhaust flows up the side ports in the side housings, into the intake manifold to help warm up the manifold for a faster Idle when the engine is cold. know some exhaust flow runs up the middle side housing to the EGR valve and through your EGR valve into your primary intake port runners. this EGR map is for non turbo models. Turbo models work almost the same way. but your EGR valve is located in your intake manifold, this time instead of your exhaust flowing back into your primary port runners, it will flow into the intake manifold.. EGR valve is there to make less power & choke your engine... but if your going to go through emissions ya might need it.......

 

I don't totally agree with JUDGE ITO except on the egr. The primary purpose of the passages in the intake manifold for a N/A is as follows. The ACV has a function called PORT AIR. There is a check valve the PORT AIR flows thru, from the airpump originaly, that is located at the ACV. Air flows thru the check valve thru two passages in the intake manifold. One passage goes fwd, the other aft to the respective end housings. Enters the end housings thru a square looking hole, travels downward and exits a triangualar passage to the front or rear rotor housing. There it has but one path, and that path is to the diffusers in the exaust ports where it mixes with the exaust to aid in emissions.

 

The EGR is not an emissions device. It is designed to lower combusiton chamber temperature by introducing oxygen poor exhaust gasses into the intake. The reason for this is to reduce or eliminate detonation at certain throttle steetings.

 

That's the great thing about Wild Wonderful West Virginia. It can be blocked off

 

Actually the EPA says that the EGR is there to lower NOx emissions, which are quite low already on a rotary.

Is it fair to say that since I have the RB headers, the EGR doesn't function anyways? Headers block the small circular hole below the rear port.

 

I'd say your perfectly right. Glad you said the RB header blocks it. I have the RB dual and couldn't remember if it was blocked or not. Can't believe I spent 125 for that darn egr valve. What a waste of good money.

 

I never said it was the primary reason. Don't forget it's also there to heat up your intake manifold for a faster smoother idle...

 

The higher your air intake charge temperature, the higher your combustion temperature will be and could detonate. When u introduce recirculating exhaust gases into your intake charge your increasing your intake air temperature, in return increasing the possibilities of detonation.. that is the case and point with turbo chargers.. EGR valve is there for emissions...

 

I can buy into the secondary purpose of heating the intake manifold to some degree, but at idle the fresh cold air from the airpump is passing thru the Port Air check valve into the intake manifold, so I have a problem with the exaust heating it. The way I see it there is a low pressure point at the diffusers and a high pressure at the acv checkvalve, so the flow should be from the air pump towards the exaust port. Just being argumenative today. Who really cares anyway. Seems everyone around here rips parts off instead of making them work anyway. Grouchy today too.

 

EGR valve doesn't open until after warm up, according to Chiltons. Thus it doesn't help warm up the intake manifold.

 

Judge Ito:
I do not wish to start a flame war, but you are wrong regarding the EGR. Yes, I would agree that introducing fresh air into the combustion chamber would enhance ignition and increase the chances of detonation, but the EGR does not do this.

The EGR instead introduces SPENT combustion gasses. This is oxygen poor and thereby reduces the combusiton effeciency. The subsequent combustion is less powerful because there is much less oxygen to mix with the fuel. The combustion temps are therefore lowered and the detonation is eliminated. The EGR is disabled with a wide open throttle condition on other vehicles I am familiar with. I would assume the same applies to the rex.

 

no problem man... just here to help. plus we are getting away from the point in hand...

 

Remember the route the exhaust gases take. up the centre housing to your EGR Valve and up your side housings through your intake manifold, it's always flowing hot gases through your manifold before your EGR valve opens...