Someone Please Explain SD and MAF systems to me.

yo,
Speed Density EFI; "...In 1986, Ford switched to EFI on 5.0 Bronco engines. 1987 brought the first EFI 5.8. The EFI Ford used for almost all Broncos is what is called speed density. Speed density EFI uses a manifold absolute pressure sensor (MAP), a throttle position sensor (TPS), an air intake temperature sender (ACT) , and the knowledge of the factory intake/exhaust tract which gives your engine certain volumetric efficiencies over it's RPM range. This allows the EEC-IV (Electronic Engine Control IV) to determine the mass (different than volume) of air coming into your engine, and hence the amount of fuel needed to go with this air. Speed density EFI also uses what is called bank fire injection. 4 injector are fired at one time on each side of the engine (only 2 wires for firing injectors from EEC-IV)...."
Source: by James O at off-road.com

Mass Air EFI; "...A mass air sensor directly reads the mass of air (or number of molecules of air). By doing this, it can detect the changes in the volume of air, in addition to it's pressure and temperature. Mass air EFI is usually what is called SEFI (Sequential Electronic Fuel Injection), which has one separate wire for each injector and fires them twice for every power stroke of the engine. This makes the injector timing more accurate and will help emissions along with power..."
Source: by James O at off-road.com
Read MORE at http://www.off-road.com/trucks-4x4/tech/big-bronco-mass-air-conversion-info-18952.html
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John, you have a Manifold Absolute Pressure (MAP) Sensor in that 4.9;

I looked at your yr/4.9 VECI Label using the 1st Cal # (2-51E-R00) in the list and it shows the MAP; here is an image;


See where the "HDG (49 States) Decal" above the label on the on-line version?
And at bottom inside the label, "This vehicle conforms to U.S. EPA regulations..."..etc.
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but for Cal # 2-51R-R00, I see "HDT (California) Decal"

So look at your CAL # and see what it says...compare the online version to what is on top of your radiator, passenger side usually.
And at bottom inside the label, "This vehicle conforms to U.S. EPA and California regulations...."..etc.

Vehicle Emission Control Information (VECI) Decal;
Vacuum Diagrams & Calibration Parts List for 88 & UP.
On-Line for Free at Ford.
Click "Quick Guides" in left panel;
Scroll to & CLICK VECI Labels "Provides Vehicle Emission Control Information (VECI) and a related calibration parts list."
Enter applicable info (need to know your Calibration number from your B-pillar sticker).
Vacuum Diagram is the same as the one on the core support or hood or air filter cover.
Source: by Ford motorcraftservice.com @ http://www.motorcraftservice.com
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GL

yo J
Did you ever get those DTCs cleared-up?
here is your thread; http://fullsizebronco.com/forum/showthread.php?t=171591
you had 553 (O) AIRD solenoid/circuit failure
& DTC 311 - Thermactor air system inoperable
The 2ndry air system is known to fail in a wide variety of ways. The check valves that prevent hot exhaust from entering the rubber hoses age, rust, leak, & crack open melting the plastic TAB & TAD valves, creating exhaust leaks that can damage other components, raising exhaust oxygen levels (setting lean codes or rich adaptive limit codes), and making rattling noises. The hard steel tubing between the exhaust & the check valve can rust or crack (especially the infamous "crossover tube" on the backs of V8 heads). The vacuum controls leak (including the "coffee can" reservoir on the R wheelwell), get misrouted during other repairs, or the diaphragms rupture. The electronics that control the vacuum controls can fail electrically or mechanically, or the wires can be damaged. But all of these failures are either A) relatively cheap & easy to repair, or B) cheap & easy to prevent with normal inspection & maintenance. see http://www.supermotors.net/registry/media/589993

plus... some that were caused by self test procedures...
common reasons for a rich running condition are a faulty fuel injector(s), bad Fuel Pressure Regulator (FPR) or a problem in the ignition system (plugs, wires, cap, distributor, etc.).
These problems will not throw codes directly
How does the exhaust look? black smoky?


Pull the vacuum line off the FPR; any hint of gas aroma or gas is a sign it's shot.

maybe the PCV valve has worked it's way out of the grommet?

ok, because of the possibility that (following is an excerpt of a condensed discussion of how a bad TAB/TAD/vac line DTC 311 ... and so-on problem could cause the rich aroma;
"...Your smog pump... blows fresh clean air up through a hose to the diverter valve. The solenoid next to the diverter valve which has a .... pink little hose plugged into ... it, creates a vacuum (sucking) that opens up the valve, and allows the fresh air to pass through the valve and make it's way to the exhaust, where the cats burn the unburnt gas more efficiently since this all happens during "open loop mode". Open loop mode happens when you turn on your car and it revs at 1200rpms for the first 15-20 seconds. During this process, your ECU feeds more gas to the engine to warm up the car quickly before driving. (also known as choke on older cars). During this open loop procedure, the extra unburnt gasoline will usually cause your exhaust to smell very rich, and the air that this diverter valve sends to the cats, causes it to burn the extra unburnt gas more efficiently like I mentoined above...thus eliminating the rich gasoline smell that us older mustangs sometimes suffer from..."
by 006 (Speedconcepts)

yo,
VALVE ASSY., (Thermactor Air Control Solenoid Vacuum) E7TZ 9H465-A avail @ Troy Ford via Amazon (great source! save $100.00 EACH on both DPFE & IAC sensors last year plus free shipping on many parts and no sales tax, so my savings over 4 local Ford dealers was over $225.00 total

$37.49 + $12.00 shipping
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VALVE ASSY., (Thermactor Air Control Solenoid Vacuum) E7TZ 9H465-B
Same price at Troy http://www.amazon.com/gp/offer-listing/B000O0QUUU/ref=dp_olp_0?ie=UTF8&redirect=true&condition=all

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These are same PN for many Broncos and Fords..incl back to at least an 89 Bronco up to my 96 5.0
So yard parts are readily avail.

and as our pal SigEPBlue wrote here recently; It's an emissions part, so you should be able to get 'em still. They were made by Rochester for Ford, IIRC. Should be service numbers E7TZ-9H465-A and E7TZ-9H465-B..."
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Ford MC parts used to have an interchange search but since they "improved" their web site, all the good stuff is gone incl these Air Sys emission parts.

http://www.fordparts.com
now, when entering my 96's VIN; the message come up as "We're sorry, the VIN you entered is not supported by the catalog at this time."

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