I have no EGR valve
 

Well I guess I have no EGR valve. I pulled the throttle body off and could not find the EGR valve where it was suppose to be according to the service manual. I'm wondering if someone replaced the engine sometime back?

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That means you have less trouble than I have.
What year is your car?
I understand that some of the newer cars have done away with the EGR system.

I have a 2000 Mazda Protege LX and according to the service manual I should have an EGR valve. I just bought this car so maybe the previous owner had changed out the entire intake manifold from another car?`

I have a '98 Protege and it does have an EGR system. My intake manifold looks different from yours. I have EGR portholes at the 6 o'clock and the 12 o'clock positions of the mouth of the intake manifold.
Do you have an EGR boost sensor on the firewall, passenger side?
Unfortunately I don't have access to 2000 model to confirm or dispell your suspicions.

Do you have drivability problems or are you just curious to know?

Right now I'm just curious. The service manual says I should have EGR valve connected directly to the throttle body on the underside. My son and I looked when I had the throttle body off and could not find the EGR valve.

Alright I think I've confirmed my suspicion that there is no EGR valve on my Mazda. I think I've found the EGR Boost Sensor and the vacuum tube has been cut. I also cannot find the EGR valve. I suspect that the previous owner became tired of the EGR issues and somehow had it removed. When I drove the car you couldn't tell there was any problems so I guess I won't worry about it anymore.

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I agree.

The EGR system reduces the production of NOx (nitrous oxides) by limiting the combustion temperature. The exhaust gases are inert and put some distance between the oxygen and the fuel molecules.

As long as you don't tell any environmental purists you should be fine.

I copied a picture from a 2002 Mazda Protege to show the metal tube from the exhaust manifold that routes back to the EGR valve.

I don't have that metal tube because the opening from the exhaust manifold is capped off.

This reaffirms my suspicion that I do not have an EGR valve.



http://www.autotechonwheels.com/imag...otege-idle.jpg

Bingo.

Did the PO remove the bulb for the check engine light? Turn the key to light up the christmas tree without starting the engine. If the CEL does not appear the bulb has been removed.
If you don't want to install an EGR system it would be adviseable to keep close tabs on the fuel consumption as a rough indicator for maintenance needs arising.

Good point about the check engine light. I checked (pun intended) and the check engine light does come on.

After I find this vacuum leak and stop the fluctuating idle and stalling issue I will monitor the MPG.