I've been fighting with the EGR for a while now. When the vacuum source is connected, I can feel the valve opening repeatedly. It causes a slight, but very annoying surge condition and cruise and low speeds/light throttle. Right now, I have a cap over the vacuum port with the vacuum line pushed onto the cap. I know the 307 is designed for EGR and I want it to work properly.

Late last year, I replaced all my vacuum lines, but I think I might have misrouted the vacuum lines to the EGR solenoid. I don't know how I missed it, but I see a disconnected vacuum port at the bottom of the solenoid.. The emissions decal makes no mention of the third vacuum port that I found. Everything looks correct per the diagram. I couldn't find any information in the CSM either. I've attached a picture for reference. Anyone have an unmolested `83 307 Y they can look at? Thanks so much!

 

The hoses seem to be in right places. According to my '86 manual, the source should be "ported vacuum", a connection at the front of the carb area.
The 'open port' you have arrowed looks to be the electrical connector.

The 5.0L valve is a positive backpressure type, which uses exhaust pulses sent though the shaft of the valve to hep control it.
It sounds like your surging may be caused by too much EGR.
Have you taken the valve off and cleaned it out? You have to make sure the center of the shaft is clear also.

My 86 has a slightly different solenoid than yours and I am not sure how much of this will apply to the 83 models..
Pulling the valve and verifying it is clean is applicable though.

 

Rob, thanks for your response!

That was the best shot I could get. Under the connector there is a vacuum port, I swear!

I did per the CSM. Did I do it right? Who knows?

You mean the part that protrudes from the bottom of the valve or further down?

I like the suggestion of too much EGR. I'm wondering if the "professional" that installed the EGR for the prev. owner needed to install one of those orifice washers. I don't see anything like that on it.

 

I am now wondering if he installed the right one! There are several varieties.
If you connect a hose to the EGR and pull a vacuum, does it open or do you keep sucking and nothing happens? If the later, the valve would be a positive or negative backpressure valve. If it opens and holds a vacuum, then you might have the wrong one.

Also, is the solenoid block original? I know the ones used on V6s use a different solenoid with an EGR vent on it.

 

You can usaully have EGR valves tested at an auto parts store. Either that or they have a tester you can rent. All you have to do is apply vacuum to it like Rob said and make sure it seals properly and doesn't leak vacuum.

 

I have a friend with an 83 Toro that may be able to help - will send him this link

 

I prefer the cheap fast easy way.
Remove hose from EGR. Install 2' section of clean vacuum hose. Suck on hose.
If it holds vacuum, then you may have a 3.8L valve on it.
If it does NOT hold vacuum, then it might be correct for a 5.0L. It will be either a pos or neg backpressure valve. These regulate vacuum based on exhaust backpressure and do vent to the atmosphere.
These types will not hold vacuum by design.

 

I tested it with my mityvac and it did not hold vacuum. That would lead me to believe it's a positive backpressure valve, which is the right one for the 307y.

I know the valve is doing it's job, it's just doing it too well.

jeffreyalman, thanks! I've looked up the solenoid at a number of different auto parts websites and no one lists the 5.0 solenoid, only the 3.8, which is clearly different from what I have.