camorra

california spec car have an electrical sensor on the EGR valve, that reports the valve's position to the ECU and that will cause the "check engine" light to illuminate.
so far so good, but what the heck is EGR stand for and where is actually the problem?
camorra

Mahjik

iTrader: (1)

Try this thread:

https://www.rx7club.com/forum/showth...light=egr+code

Don't forget to use the search engine. You can generally find the information you are looking for a lot quicker than waiting for someone to reply to a message.

Mahjik

iTrader: (1)

BTW, another link:

https://www.rx7club.com/forum/showth...light=egr+cure

Toadman

Exhaust Gas Recirculation Valve. In all combustion engines a certain amount of unburned fuel gets through the exhaust valves(or ports in the rotary) Some of this gets recycled back into the intake thru this valve. It's a smog valve to reduce unburned hydrocarbons at the tailpipe.

spurvo

EGR = Exhaust Gas Recirculation. This is one of the earliest emissions control devices placed on engines (PCV being the first, I believe), starting in Calif around the mid sixties.

Under certain driving conditions, a valve opens that allows exhaust gasses to enter the intake stream. This introduces exhaust gasses to the intake charge. It reduces the emissions of unburned hydrocarbons (incomplete ignition) and oxides of nitrogen (referred to as NOx) that are harmful to ozone and humans. The manual states, "This system recrculates a small amount of exhaust gas into the intake manifold to reduce the combustion temperature and reduce NOx emissions." (page F-125 in the 93 manual) I don't have access right now to all the reactions that take place to make this happen. Maybe later if anyone is interested.

In our cars, the EGR is only open during medium engine load when warm (over 177F) between 1700 to 3850 rpm. Basically, when the engine is running at part throttle cruising. It is cut off as soon as you start accelerating, or under heavy load/high rpm. It is also cut during warm up and at warm idle.

The problem you are experiencing is that there are two "sensed" parts to your system. There is the solenoid that routes vacuum to the EGR valve to open it at the right time. If it fails, you get a check engine light. The failure here is that the solenoid is either "open circuit", which means it no longer shows the correct resistance to the ECU, either because the soleniod itself is bad, or the connector has broken/fallen off. You can test the solenoid by checking the resistance across its connector pins. Check the manual to see how this is done.

The second part of Calif cars' systems is the EGR valve itself. There is a position sensor mounted on the EGR valve that tells the ECU that it is open or closed. If it does not show open when it is supposed to (i.e. when the ECU opens the solenoid), check engine light shows up. The failure here would be a stuck EGR valve, or broken connection to the sensor.

Hope this points you in a direction. If I was going at it, I would put vacuum to the EGR valve itself first, and test the connector to see if you get continuity. See page F-127 in the manual. If that tests ok, go after the solenoid next. It is burried in the rats nest, under the UIM. not fun.

Happy hunting, hope this helped

turbojeff

iTrader: (30)

Funny thing about EGR valve gaskets. I've seen several gaskets that only have one hole, that means the factory gasket pretty much makes the EGR non-functional by blocking off one side of it.

I've seen a couple factory EGR gaskets lately that have a tiny hole in one side and the normal size hole on the other side. This hole is about the size of a pencil lead and can't flow any effective amount of exhaust.

In 95 Mazda eliminated the EGR valve. Get a non-Cal ECU and forget about the EGR valve. Non-Cal ECUs should be available used for about the same cost as a EGR valve from Mazda.

Good write-up spurvo.

Jeff

smerkinseven

mine is bad too..... but i was still able to pass smog yesterday cause with an hour and a half of tuning...

khannifer_rx7

thank you so much guys for all this info.. i swear the the EGR valve and the idling on my car scared the shtt out of me... i have the noise that i EGR valve cause.. make the car sound like crap.. thanks alot guys