yo J,
As Skitter advised &;
Try a Self Test for Diagnostic Trouble Codes (DTC)s by my pal, BroncoJoe19
http://broncozone.com/topic/14269-code-reader/page__pid__74587__mode__threaded
Joes also shows a vacuum leak test; and, check vac w/vac gauge
The vacuum gauge should show around 18-22 in-Hg @ idle & maintain a steady needle. Rev it up to ~2500 rpm, hold it steady, and you should see the needle drop, then slowly increase to a level close to the idle reading (though slightly lower is normal).
Gas Saver Vacuum Gauge, PM1520, 2 inch
http://www.autoparts2020.com/rsdev/part_detail.jsp?PART_HDR_ID=87069
Run vac hose through clutch blank and use a grommet or =; attach to vacuum tree on intake manifold; Vacuum Tree Location pic by Booba5185 @
http://i14.photobucket.com/albums/a304/booba5/overhead-2.jpg
and; The air handling system is designed to provide defrost when no vacuum is applied to any of the three air door vacuum motors. This is done to prevent a situation where defrost cannot be obtained due to a system vacuum leak. Instead, a leak in the vacuum control circuit will send all airflow to the defroster outlets. This condition may occur during acceleration (slow leak), may exist at all times (large leak) and may happen only when certain specific functions are selected, indicating a leak in that portion of the circuit.
The engine temperature must be greater than 50° F for the Key On Engine Off (KOEO) Self-Test and greater than 180° F for the Key On Engine Running (KOER) Self-Test.
Run it around to heat the engine up and shift thru all gears incl Reverse. Then turn off all accessories/lights, etc. Use heater temp (feels hot) to help determine if it is warmed up enuf for self test KOER
Engine Coolant Temperature & Sender Testing; "...If you take that single wire that Seabronc is talking about and ground it to the block the guage will imediately go to HOT that will tell you if its the guage or the sender . There is another mounted back farther in the intake and that is for the EEC to determine timing curves and injector pulse time..."
Source: by BLADE262US & Seabronc (Rosie, Fred W) at Ford Bronco Zone Forums
Testing; "...Pull the R/Wh wire straight off the sender & ground it to the block, intake, or head. Then turn the key to RUN. If the needle pegs, replace the sender. If not, diagnose the circuit
Sender Location Diagram Source: by Gacknar (The Mall-Crawler, Jeremy, "Big grey megga beast")
http://www.supermotors.net/getfile/265237/original/GT-40%20lower%20intake.JPG
Make sure A/C is off and transmission is in Park (automatic) or in Neutral for a Manual & release clutch.
Do Key On Engine Off (KOEO) portion first.
And Post em here according to:
KOEO
&
KOER
=============
Smog Diagnostic Chart; see
http://www.recarbco.com/technical/smog/smoginfo.html
altho most apply to carb engines, a lot applies to EFI
&
by Recarbco Fuel Systems recarbco.com:
PCV valve; Is it sticking open or sticking closed? Are the passages clogged or is the hose itself collapsing? A defective PCV can cause high CO or HC readings. A high CO reading will result if the crankcase oil is contaminated with fuel. A high HC reading will result if the PCV valve does not meter the airflow properly, if the incorrect valve is installed of if the vacuum side of the system is leaking air (such as through a cracked or broken hose, loose fitting, etc).
Another condition to be corrected or eliminated is catalytic converter failure or a blocked exhaust system. To check for proper operation, first block the wheels, put the vehicle in Neutral or Park, disconnect the air injection system and check that all fluid levels are satisfactory for safe operation. A) Disconnect the evaporative canister purge line.
B) Measure the HC, CO, CO2, and O2 tailpipe readings with the engine at idle and at normal operating temperature.
C) If CO and HC are above specs but CO2 is low and O2 is between 1% and 2%, the problem could be either temporary saturation of the catalytic converter or a defective cat.
D) To check for temporary saturation of the cat, run the engine at 2500 rpm for three minutes and observe the HC, CO, and CO2 readings. If the cat is functioning properly, CO and HC readings should decrease and CO2 should increase. If CO and HC do not decrease but CO2 does, repeat the procedure. If CO and HC still do not decrease, go to step 6 above.
E) Check the O2 level. If it is below 1%, the engine may be running too rich. Investigate and repair. If the O2 rises above 3 or 4%, the engine may go into a lean misfire, causing HC to rise. Again, investigate and repair. Note: the use of oxygenated fuels may push the O2 up to 3 or 4% even though nothing is wrong.