I failed the e-check a couple months ago and I did not have the EGR hooked up. I failed with way too much NOS readings. I found my EGR valve finally. I can't find the EGR solenoid. If I hook the EGR valve up to direct or ported vacuum would that help to pass the sniffer test?

 

NOx not NOS. And it may, it would depend on the test, the engine temp and a slew of other things. Go to the junkyard and get what you need.

 

The EGR solenoid is underneath the ignition coil. If you remove the 2 bolts holding the coil you'll see the solenoid. Once you remove the connectors on the solenoid you should be able to just wiggle it out of there.

 

An '83 LG4 coil is going to be in the distributor cap. i don't think the EGR valve solenoid is under there...

But, it isn't far away. The EGR valve is on the passenger side of the intake manifold, right under the carb. The solenoid is on the same side toward the back of the intake manifold - just to the right of the distributor.

Don't hook it up to carb vacuum. It isn't designed to work that way.

 

I might have to go to the junk yard to get that solenoid. Does the solenoid tell the EGR when to work?

Does vacuum make it work or does no vacuum make it work?

I was thinking maybe the EGR would work all the time with full vacuum and part of the time with ported vacuum?

If full vacuum made the EGR work all the time would it not pass the sniffer more easliy?

I should have said this was an 83 LG-4 car that has a CCC Carb.

 

The EGR valve itself is operated/opened by vacuum. The ECM tells the solenoid when to open, which puts the vacuum signal on the EGR valve.

Putting full-time vacuum on the valve will not let it idle. Putting ported vacuum on it may allow it to work somewhat properly, but that's not the way it was intended. Allowing the ECM to control it is the way it was designed.

You can get a new solenoid from the chain parts stores. Checker/Shucks/Kragen/Partsamerica has Neihof FE99B for $19.99, for instance.

Another reason for the EGR valve not to "work" is plugged up passages in the intake manifold.

 

How did the EGR operate before the ECM? I think that is the answer I was looking for. I might look into getting a new solenoid from a Advance Auto or somewhere though.

 

Before computers the EGR valve worked off of a ported (off-idle) vacuum source on the carb, qualified by a thermostatic vacuum switch in the water jacket of the intake manifold (so the EGR valve would never open until the engine warmed up some).

Once ECMs came into being they would hook them up to a full vacuum source and run them through the EGR solenoid. The solenoid would pulse open and closed according to what the ECM told it to do- 25% duty cycle, 50% duty cycle, 75% duty cycle, 100% duty cycle. When vacuum was NOT being sent to the EGR valve it was vented to open air- you'll notice an extra vacuum nipple on the solenoid that isn't plugged into anything- that's the vent. That system allowed the ECM to control how far open the EGR valve was precisely under any conditions.

 

Thanks Damon that is the answer I was looking for. Appreciate it.

 

Well it passed E-check. I hooked the EGR valve up to full manifold vacuum and then set the timing back so far it would hardly run and it passed in about 30 seconds on the rollers. Now it is put back to normal and runs great again. After the car is 25 years old we no longer have to e-check so I might not have to do it again.:lala: