So I got a cel the other day and had it scanned and it said it's my egr vavle. And I'm still kinda new to the engine so can someone help me out and tell me what the hell I have to do to get to it so I can see if I can fix it. Thanks!

 

it is better taking your car to see some profrssional mechanic, because the egr is hard to change.

 

I said nothing about changing it out. One of my friends who is a mechanic said that it would probably fix it if I break my car down to the Valve and clean off the carbon so I was going to try that. So if someone could answer my q it would be great.

 

It is really hard to change because the RX-8 doesn't have an EGR valve.

 

^^ true story. Correct me if i'm wrong MM, but an Exhaust Gas Recirculation valve would normally be found in the intake manifold. its purpose - reduce combustion temperatures and helps control the formation of oxides of nitrogen

god knows our combustion temps arent reduced by anything, lol

but we dont have one, so whatever led you to believe thats what the code was for, i wouldnt trust it anymore

 

It is usually mounted on a stand-off on the "block" of the motor with a tube or passage to the exhaust manifold and another to the intake.
The Renesis achieves EGR through minor port overlap.

 

I know all rx7 have a egr valve

 

The '8 isn't a '7.

 

no they dont.

 

Yeah, that didn't sound right.
Why would a 13b-REW need an EGR? It has so much port overlap to take care of that.

 

we kinda think the 93-94's had egr to satisfy someone at the epa, cause the egr port is teeny, and like you say its got overlap already...

 

I know this thread is old, but I was wondering, the 8 doesn't have an EGR, but would it be better with one? Has anyone tried recirculating exhaust on the 8?

 

Also....I could have sworn I read that the Renesis has no port overlap, due to the side intake ports. Is this true? And if so, how would it achieve gas recirculation?

 

I remember reading somewhere that the hydrogen renesis uses egr. EGR should, theoretically, do a lot for us. Better fuel economy when cruising, lower combustion temps, allowing us to use lower octane fuel(maybe not at full throttle?), and letting us lean out the a/f significantly during low load situations, without burning up the cat...

 

Actually, the RENESIS does have Exhaust Gas Recirculation (EGR), it is just an internal one just like previous rotary's with no "valve".

Many people do not realize that there are External and Internal EGR systems as most only see the traditional External units that involve a hose coming back from the exhaust somewhere and feeding the intake somewhere - depending on design.

The rotary has always had internal EGR to aid combustion, but the RENESIS greatly reduced (from the elimination of the port overlap) the internal amount of EGR flow for better combustion stability at low volume flow (idle) and better combustion efficiency.

Reference the attached SAE Paper on "Developed Technologies of the new Rotary Engine (RENESIS)". Specifically Page 8 and Figure 16, as these show the amount of EGR flow for the RENESIS.

 

My understanding from that white paper is that they did the best they could to eliminate exhaust gas recirculation, but a small amount (10%) of exhaust gas gets trapped in the chamber volume at TDC and doesn't quite make it out of the exhaust port. There is clearly no external EGR, and it seems like Mazda went from one extreme to the other.
Reducing internal EGR to a minimum has provided us with considerably more power, NA, than the previous 13b, but it also lowered possible fuel economy. The other changes made to the RENESIS have made up the differences, but I would imagine fuel economy would be greatly increased by adding an external EGR system... In addition to the other benefits that would come from it.

That white paper is a very interesting read, though. Thanks!