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How do I did out what the original emissions setup was??
Bought a 95 250 5.8 w less than 100k on it for 2k, only big prob is no emissions, other than a muffler, nice if I kept it in the country but here in Pittsburgh they do this thing called emissions test.... So I got to put it all back in there, no I'm not up for registering it where its not tested, more hassle than it's worth down the line.
Most of it is self explanatory, I'm hesitant on the lines coming from the air pump, what's left under the hood looks like a cross between 2 setup diagrams I've seen on ford-parts. I've checked a few 250s I've come across but have not seen anything that seems a dead match. Shop manual did not have enough specifics that I saw.
Figure I'll have to go to ford to get some of these parts so I don't want to guess. Already hit up a pick a part to get vac resevoir and a few other parts.
I am pretty familiar with the Thermactor air injection system. This image was created by jrichkler on Stangnet. These trucks use this system with a couple slight variations.
The smog pump always pushes fresh air toward the TAB (bypass valve on the diagram above). By default the TAB is closed. In order to open the TAB the EEC will ground the TAB solenoid, which opens the solenoid. This allows manifold vacuum to be pulled from TAB through the TAB solenoid and finally into the vacuum reservoir.
With the TAB open fresh air flows from the smog pump through the TAB and on to the TAD (diverter valve on the diagram above). By default the TAD is closed. When closed, the TAD directs fresh air to the catalytic converter. In order to open the TAD the EEC will ground the TAD solenoid which opens the solenoid. This allows manifold vacuum to be pulled from the TAD through the TAD solenoid and finally into the vacuum reservoir. (exactly the same as the TAB).
With the TAD open fresh air does not flow to the cat, it flows into the crossover tube located on the back of the cylinder heads, into the cylinder heads and finally into the exhaust runners. There are also a couple of check valves in-line: one between the crossover tube and the TAD and the other between the cat and the TAD. I believe these are to protect the valves against backfires.
The solenoids are mounted on top of the motor on the driver's side next to the coil mount. There are three solenoids there; TAB (rear), TAD (middle) and EVR (front). The The EVR solenoid operates exactly like the TAB and TAD solenoids but controls the EGR valve. The TAB is behind the smog pump. The TAD is around the back side of the motor on the pass side. The EGR hooks the the pass side exhaust manifold and the pass side of the throttle body.
The The entire system relies on small plastic vacuum lines that are prone to cracking.
Very helpful!! knowing that ford calls it the thermactor is big, i can search for that.
There are a few parts still in place, I think to trick the eec? still there are solenoids and egv and a few vac lines, though i understand its prob best to replace the old vac lines anyway.
seems in line with how I was understanding the setup, but you explained the process which will help trouble shoot.
Ive seen a setup in a 250 like this picture diagram and is the way im leaning, but it sounds a little off in terms of the location of parts from what you describe:
Also im planning on replacing the headers (decent 4-1 in there now but rusty) and wondering if its common and legal to weld bungs in for the egr and O2 sensors?
I've never seen the components mounted on the driver's side of the motor as you have pictured, but my experience has been with Mustangs, Mark VIIs and Broncos.
Your setup looks like it uses a combo TAB and TAD valve, which I believe was also used on Crown Vics.
For the vacuum lines, some of the Bronco guys are running thick wall silicone tubing. (I did this on my Bronco before I sold it.) Check the 10th post down of THIS THREAD for what to get. I ended up getting like 20' of black thick wall 4mm silicone hose on ebay for about $10.00. That was enough to redo the brittle vacuum lines.
I can't help you with the exhaust bungs but suggest reading through your states DMV website.
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