Failed the smog check, I have a disconnected line to what shows on the decal as "ACV". Its a round circle type symbol. Whatever is supposed to be there has never been there since I bought the truck in 1995.

Went to a different test station and they spent way too much time under the hood and found it. I can't find any reference to it other than a "Combination Bypass Valve/ Air Control Valve." I don't think I have that type. My bypass valve is shown separately on the decal. The hose that's plugged runs back near the EGR valve.

Speaking of the EGR, it has the integral backpressure type valve.
I have changed out my exhaust to a three inch converter and muffler. Would you suppose this would keep the EGR from working as it should? It has passed in this configuration before, but failed the NOX test this time around. If I remember right NOX is a function of EGR, correct?

Have I mentioned how much CA laws suck?


Thanks for any thoughts.

 

I looked up the "ACV" and there are two types. Just an air control valve, or as you found out the "combination bypass/air control valve. Both of them go to the smog pump. You should have a valve that has the large lines from the smog pump system that go to it. That is the ACV. It directs the air from the smog pump to different places on the engine depending on "engine control strategy".

The plain valve has three large connections and one small vacuum connection

The combo valve has three large connections and two small vacuum connections.

About your egr valve. Been there done that. I found my engine started pinging when I put headers and free flow exhaust on it. I found the egr not working. After cutting it apart, I found out that there is the large diaphram that actuates the valve, like you would expect. But this diaphram has a hole in the middle of it. This hole has a metal diaphram underneath. This metal diaphram is actuated by exhaust backpressure. As rpms increase, you get more backpressure which pushes the metal diaphram up, blocking the hole(which leaks vacuum otherwise). Not enough backpressure, and the metal diaphram will never plug the hole enough for the vacuum to build and open the egr. It has a filter underneath the valve for the vaccum bleed to draw through.

I wonder if you can stuff some steel wool in the tailpipe and make it work for the test?

By the way, what year truck and size engine do you have?

 

It's an '86 F150 4x4 with what was the HO 351. Pretty much the same engine, been rebuilt and the manifold is now a Performer RPM.
The bypass valve I've always had on it is just a standard valve. Perhaps it is not the correct one, I don't ever recall seeing the other type.
The EGR valve is functioning, the test Ford calls for involves plugging the tailpipe to 1/2" to restrict flow and THEN pulling vacuum on the EGR valve. That does work. If it works in normal operation, I don't know.
They also wrote me up for only having one converter. Did Ford make these with two originally? Maybe if I added another it would cause enough backpressure to work the EGR, kind of a gamble there.
Might have to go check in with the dealer to see what they try and sell me for a bypass valve and/or an ACV.
Can't think of much else to do.