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When I removed the intake runners they were sooty, oily. I posted a question why, no replies.

In my speedo box post, that the plug-in end at the box is shot, the idea the EGR valve being dead or out of the system may cause soot in the intake runners appears.

New engine going in. I believe I'll leave the EGR valve as is, ( not knowing if there is one in L-Jet '79 - '81 ) not worry about the plug for now.

If anybody knows basic emission control system, what does what, is necessary, why, good to read or FAQ.

T.Hanson wrote:When I removed the intake runners they were sooty, oily. I posted a question why, no replies.

In my speedo box post, that the plug-in end at the box is shot, the idea the EGR valve being dead or out of the system may cause soot in the intake runners appears.

New engine going in. I believe I'll leave the EGR valve as is, ( not knowing if there is one in L-Jet '79 - '81 ) not worry about the plug for now.

If anybody knows basic emission control system, what does what, is necessary, why, good to read or FAQ.

I will try to answer this later. I work as a research engineer on after treatment systems for diesel engines. So perhaps I can shine some light on the matter. Ask me some more focussed questions as th question is now quite broad.

Regards,
Jan

T.Hanson wrote: I believe I'll leave the EGR valve as is, ( not knowing if there is one in L-Jet '79 - '81 ) not worry about the plug for now.

FWIW, I have no EGR system on my L-jet.

If USA '79 to '81 L-Jets don't, then mine don't.

Except my speedo box plug-in, Mike said the broken boot, wire plug was to the EGR warning light, but its' not lighting wouldn't matter, which lead to more posts about removing from / plugging the EGR valve.

Haynes has a bad schematic title emission control system, but not specific if it's for L-Jet or reactors/carburetor.

You are aware there 2 lights on the center dash module ('80) that illuminate when the key is turned to the 'on' position. (Have you ever seen them? - maybe not)

One is 'Fasten Seat Belts' (center) and the other (left) is 'Oxygen Sensor' (there is nothing on the right side). The seat belt light is on a timer that extinguishes no matter how the belts are connected or not. The O2 bulb is hooked up to the mechanical 'clock counter' switch (left frame box). It turns on at 30,000 mi. intervals driven by the speedo cable on its way to the dash but in no way is part of engine management. It is simply a reminder to have your O2 sensor checked or changed, nothing more. It is grounded through the oil pressure switch, so when you start the car and the oil switch is satisfied, both the oil light and this O2 light are extinguished. Additionally, when the clock counter switch is turned on it is grounded directly. So there are three wires attached to the connector that plug into the box. Brown, brown/green and white. White is the bulb lead to the dash, brown/green is a 'switched' ground (through the oil pressure switch) and you know what brown is for.

Point I'm getting to is the plug on the box you reference is just the wiring to and from this mechanical switch for the O2 light on the dash and its respective grounds. That's it. It won't hurt anything if you remove the wiring (neatly) but I have mine in service just because that's how I am.
Capiche?

Would this mean that if the wires are not connected to the box on the frame, under the car, that the oil light would not work as well?

No, the pressure switch ground feeds the two lights independently. I've circled the connection in white. If, however, you manage to disturb this connection and the oil switch sees no ground, (brown/green) then yes, the oil light would not work.

Smart people have no idea how stupid stupid people are.

My whole entire speedo box plug in, rubber boot, wires to white plug, etc. is wrecked. Speedometer cable is fine, the other deal is crunchy, broken, dead.
All of it. Hanging dead.

Now what happens. I am rather fond of low oil warning lights.

I would assume that your oil light works? Yes?
I would assume your O2 light doesn't/hasn't/never did work?

If those assumptions are correct, then don't do anything.

I'll expand on it a little bit more, does your speedo work? If so, I'll second Lenny's recommendation. Don't sweat it.

I hope you have answers to your wiring question.
Now back to your original question about oil/soot in the intake -- that likely means you have a slight vacuum leak in one of the engine seals so oil is being sucked up as the engine is running.