gwgeep

Last week I replaced/repaired vacuum lines on my 1994 F150. I used the following diagram on my hood. The lines near the fire wall were brittle and I used rubber vacuum hoses for repairs. It all runs great and no Check Engine Light issues. Now, I have a question about some items on the diagram. What exactly is the Air A/Air D? It looks like it controls the Eng and CAT Converter? I think the FPRC controls Fuel rail. I was wondering if the Air A/Air D control lines would create Engine Codes if those lines were leaking or broken? Or would broken lines just make the vehicle operate poorly without giving codes? Would tuning the engine with plugs, wires, rotor cap, etc. overcome any broken lines in the Air A/Air B lines? My F150 really operates smoothly and like a dream after replacing/repairing the lines, BUT, I never did get codes to indicate otherwise. Just curious.

Chris_1

iTrader: (1)

I'm going to just guess at that and say they're probably the 2 vacuum operated valves that divert fresh air from the air pump either through the heads or down to the cats. Mounted on the crossover pipe at the back of the heads on a v8. Wouldn't necessarily throw a code but could; a vac leak there would cause idling / running issues when those vacuum lines were in use but not when the main vac solenoids to them were closed.

gwgeep

Thanks! I did a quick search on those terms and found a few threads. I just never gave this a thought or bothered to check into this over the years. Appreciate it!

Chris_1

iTrader: (1)

That whole fresh air system is called the thermactor system.