yo BIG,
DTC 121, 122, 123, 124, 125 & DTC P0122, P0123 & P1121 in TSB 94-26-4; "...The following is a list of vehicle symptoms which have been associated with the TPS, but can also be related to other vehicle components. Check engine light, Stalls, quits, hesitation/stumble, fast idle; To minimize the replacement of good components, be advised that the following non-EEC areas may be the issue: Excessive blow-by, PCV malfunction, Vacuum leaks, Fuel pressure, Throttle sticking or linkage binding. MANY VOLTMETERS WILL AUTOMATICALLY CHANGE RANGES WHEN MEASURING TPS OUTPUT FROM IDLE TO WOT. WHEN A VOLTMETER IS USED TO MEASURE TPS OUTPUT FROM IDLE TO WOT, THE METER SCALES OR CHANGES RANGES AUTOMATICALLY. THERE MAY BE AN ERRONEOUS METER DISPLAY UNTIL THE VOLTMETER HAS LOCKED TO THE APPROPRIATE VOLTAGE READING. THE ERRONEOUS METER DISPLAY DOES NOT REPRESENT A DEFECTIVE TPS. NOTE: IT IS RECOMMENDED THAT THE "RANGE LOCK" FEATURE ON MANY METERS BE SET FOR CHECKING TPS VOLTAGE..."
Source: by Ford at /
http://www.tccoa.com/articles/mn12-techinfo/tsb/tsb-94-26-4.pdf
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DTC 126-129, P0235-P0237; "...On gasoline engines, the manifold absolute pressure (MAP) sensor senses atmospheric pressure to produce an electrical signal. The frequency of this signal varies with intake manifold pressure. The powertrain control module monitors this signal to determine altitude. The PCM then adjusts the E4OD shift schedule and EPC pressure for altitude. On diesel engines, the MAP sensor measures boost pressure. The PCM monitors this signal and adjusts EPC pressure. Symptoms: Firm shift feel, late shifts at altitude..."
Electronic Pressure Control (EPC) Solenoid:
Description: The Electronic Pressure Control solenoid is a variable force solenoid. The variable-force type solenoid is an electro-hydraulic actuator combining a solenoid and a regulating valve. It supplies electronic pressure control which regulates transmission line pressure and line modulator pressure. This is done by producing resisting forces to the main regulator and the line modulator circuits. These two pressures control clutch application pressures.
Symptoms: Failed on minimum electronic pressure control pressure (minimum transmission torque capacity). Limit engine torque (partial fuel shut-off, heavy misfire). Flashing transmission control indicator lamp.
Failed off maximum electronic pressure control pressure, harsh engagements and shifts. May flash transmission control indicator lamp.
Diagnostic Trouble Codes: 624,* 625,*
CAUTION: The electronic pressure control pressure output from the variable force solenoid is NOT adjustable. Any modification to the electronic pressure control solenoid will affect the transmission warranty. (*Output circuit check, generated only by electrical condition.)
Source: by Ford via Steve at
http://www.supermotors.net/registry/media/704885
Manifold Absolute Pressure (MAP);
Testing, Symptoms & Overview; "...a multimeter that can read frequency is normally required to check the sensor’s output. But you can also use an ordinary tachometer because a tach can display a frequency signal. Here’s the procedure: Connect the two jumper cables the same as before, (see diagram in site) attaching each end terminal on the sensor to its respective wire in the wiring connector. If you want to measure engine vacuum so you can correlate it to a specific frequency reading, connect a vacuum gauge to a source of manifold vacuum on the engine, or tee the gauge into the MAP sensor hose. Turn the ignition ON and note the initial reading. The reading on the tachometer should be about 454 to 464 at sea level, which corresponds to a frequency output of 152 to 155 Hz. Start the engine and check the reading again. If the MAP sensor is functioning properly, the reading should drop to about 290 to 330 on the tachometer, which corresponds to a frequency output of about 93 to 98 Hz. No change would indicate a defective sensor or leaky or plugged vacuum hose..." a vacuum gauge to a source of manifold vacuum on the engine, or tee the gauge into the MAP sensor hose.
Source: by wellsmfgcorp.com
Testing, Symptoms & Overview; "...Surging, Rough idle, rich fuel condition, which may cause spark plug fouling,Detonation due to too much spark advance and a lean fuel ratio, loss of power and/or fuel economy due to ******** timing and an excessively rich fuel ratio, vacuum leak will reduce intake vacuum and cause the MAP sensor to indicate a higher than normal load on the engine. The computer will try to compensate by richening the fuel mixture and retarding timing -- which hurts fuel economy, performance and emissions..."
Source: by aa1car.com
Pull & inspect a few spark plugs...
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DTC 181
From 94 Bronco Manual by Ford (following Ford test requires at times a breakout box; go to the EEC CONNECTOR pin instead; for instance - Measure resistance between Test Pin 33 at EEC connector to ground)
These DTCs indicate the system is running lean, although strategy adjusted it to maximum rich: DTC 181 Right or Rear Rich limit reached; 183 Right or Rear Rich limit reached @ idle; 189 Left or Front Rich limit reached; 192 Left or Front Rich limit reached at idle.
These DTCs indicate that the system is running rich, although strategy adjusted it to Max. lean: 179 Right or Rear Lean limit reached; 182 Right or Rear Lean limit reached at idle; 188 Left or Front Lean limit reached; 191 Left or Front Lean limit reached at idle.
Possible Causes:
Fuel pressure.
Fuel injector.
Air intake.
MAP sensor (ignore).
Fuel injector electrical circuit.
Fuel filter.
Vacuum.
Air filter.
Are any other DTCs present?
Yes SERVICE as required.
No GO to HA2
HA2 CHECK FUEL PRESSURE
WARNING: THE FUEL SYSTEM WILL REMAIN PRESSURIZED WHEN ENGINE IS NOT RUNNING. TO PREVENT INJURY OR FIRE, USE CAUTION WHEN WORKING ON THE FUEL SYSTEM.
Key off.
Install fuel pressure gauge.
Verify that manifold vacuum is connected to the fuel pressure regulator if applicable.
Start and run engine at idle. Note fuel pressure.
Refer to Fuel Pressure Specification Table .
Is fuel pressure within specification?
Yes GO to HA3
No VERIFY integrity of fuel pressure regulator, vacuum line, fuel filter and fuel lines. REFER to Section 9A
HA3 CHECK SYSTEM'S ABILITY TO HOLD FUEL PRESSURE
Cycle the key on and off several times. Note the fuel pressure.
Visually look for fuel leaking at the injector O-ring, fuel pressure regulator, and the fuel lines to the fuel charging assembly. Service as necessary.
Does fuel pressure remain at specification for 60 seconds?
Yes VERIFY integrity of air intake,
air filter, no vacuum leaks, EGR valveclosed.
For vehicles with MAP/BARO: GO to HA4
For all others: GO to HA6
NO REFER to Section 9A. Fuel Delivery Diagnosis section, although the problem may be elsewhere. prevent the replacement of good components, the following areas may be at fault:
Battery and charging system low (fuse integrity).
Contamination within the Idle Air Control (IAC) device.
Contamination of fuel.
Octane rating.
Plugged or restricted fuel filter.
Engine not reaching operating temperature.
Cooling system (low/leaking).
PCV system (incorrect/clogged).
Transmission, Clutch integrity.
Brakes (not releasing).
Ignition system.
Exhaust system, EGR.
Vacuum leaks (air intake manifold, vacuum hoses, vacuum reservoirs, power brake booster, as applicable).
Verify
Transmission in PARK or NEUTRAL.
Parking brake applied (automatic brake release disconnected where applicable).
Wheels blocked.
Transmission fluid integrity.
Transmission shift timing.
Adequate fuel supply in the tank.
Fuel system integrity (leaks, restricted or damage).
Fuel system electrical integrity (Inertia Fuel Shutoff (IFS) switch).
Generator belt tension.
Heater and accessories off.
Throttle lever is resting on the throttle plate stop *****.
This is the basic FP testing Section & FDS3 CHECK FUEL PRESSURE LEAKDOWN
Observe the "Notes, Cautions and Warnings" to avoid fuel spillage and injury.
Connect the Fuel Pressure Test Kit at the fuel pressure test point.
Connect a jumper to the FP lead of the DLC.
Key on, engine off.
Ground the test lead using the jumper wire to run the fuel pump.
Run the fuel pump for 30 seconds minimum.
Remove the test lead ground and note fuel pressure on the gauge.
Verify whether the fuel pressure remains within the specified 5 psi for 1 minute after the test lead is ungrounded.
Does fuel pressure remain within 5 psi for 1 minute after the test lead is ungrounded?
Yes GO to FDS5.
No GO to FDS4.
FDS4 CHECK PRESSURE REGULATOR DIAPHRAGM CONDITION
Key off.
Connect Fuel Pressure Test Kit at Schrader fitting on rail. Observe Warning Instructions to avoid fuel spillage and injury.
Start engine and run for 10 seconds.
Stop engine and wait 10 seconds.
Start engine and run for 10 seconds.
Stop engine and remove vacuum hose from pressure regulator.
Examine vacuum port in the pressure regulator for evidence of fuel leakage through the diaphragm.
Is vacuum port free of any fuel?
Yes GO to Group 10 of the Service Manual for leak test.
No REPLACE pressure regulator and RERUN test FDS2.
FDS5 CHECK FUEL PRESSURE WITH ENGINE LOAD
Fuel pressure test kit installed.
Disconnect vacuum hose at the fuel pressure regulator and plug it.
Observe fuel pressure while driving vehicle with heavy accelerations.
On Type 2 (Dual Tank System) perform test for both tanks.
Does fuel pressure reading remain within ± 3 psi during the test?
Yes UNPLUG vacuum hose and connect it to fuel pressure regulator.
No GO to FDS6.
ETC I have the rest in my site
HA4 CHECK MAP/BARO FREQUENCY
Key off.
Connect MAP/BARO tester.
Key on.
Refer to MAP/BARO Frequency Charts on this Pinpoint Test's cover page (also Pinpoint Test DF's cover pages) to check MAP/BARO frequency. It may be necessary to measure several known good MAP/BARO sensors on available vehicles to determine area's typical reading for that day.
Is MAP/BARO frequency within specification?
Yes For vehicles with MFI: GO to HA5
All others:GO to HA6
No CHECK wiring to MAP/BARO sensor for corrosion, high resistance, etc. If OK, REPLACE MAP/BARO sensor. CLEAR KAM. RERUN Quick Test
HA5 DIAGNOSTIC TEST MODE (DTM): MFI ENGINES
Connect tachometer to engine. Run engine at idle.
Disconnect and reconnect the injectors one at a time: note rpm drop for each injector.
Does each injector produce a momentary drop in rpm?
Note: IAC will attempt to re-establish rpm.
Yes GO to Ignition Section
No GO to HA7
HA6 DIAGNOSTIC TEST MODE (DTM):
SFI ENGINES
The DTM switches each injector OFF and ON one at a time. Diagnostic Trouble Codes (DTC) correspond to the cylinder number (i.e., DTC 30 indicates a problem with cylinder No. 3, a DTC 90 indicates a pass). The DTM is designed to aid in the detection of a weak or non-contributing cylinder. The Pinpoint Test Steps are designed to isolate only EEC related problems.
Refer to Quick Test Appendix, Section 5A , for detailed information about DTM.
Run the Engine Running Self-Test.
After the last repeated code, wait 5-10 seconds.
"Goose" throttle lightly (not wide-open-throttle).
DTM will be performed. Time of test is 2-3 minutes.
Is Code 90 present?
Yes GO to Ignition Section
No GO to HA8
HA7 CHECK RESISTANCE OF INJECTOR(S) AND HARNESS MFI ENGINES.
Key off.
Disconnect Powertrain Control Module (PCM). Inspect for damaged or pushed out pins, corrosion, loose wires, etc. Service as necessary.
Note: This erases Continuous Memory.
Install breakout box, leave PCM disconnected.
Measure resistance of INJECTOR BANK 1 between Test Pin 37 and Test Pin 58 at the breakout box. Record resistance.
Measure resistance of INJECTOR BANK 2 between Test Pin 37 and Test Pin 59 at the breakout box. Record resistance.
Refer to Injector Resistance Specification Table 1 .
Is each resistance within specification?
Yes GO to HA12
No GO to HA9
HA8 CHECK RESISTANCE OF INJECTOR(S) AND HARNESS SFI ENGINES
Key off.
Disconnect Powertrain Control Module (PCM). Inspect for damaged or pushed out pins, corrosion, loose wires, etc. Service as necessary.
Note: This erases Continuous Memory.
Install breakout box, leave PCM disconnected.
Measure resistance between the suspect INJECTOR circuit Test Pin and Test Pin 37 at the breakout box. Record resistance.
Is each resistance within specification?
Yes GO to HA12
No GO to HA9
HA9 CHECK CONTINUITY OF FUEL INJECTOR HARNESS
Key off.
Breakout box installed, PCM disconnected.
Disconnect injector vehicle harness connector at the suspect injector.
Measure resistance between Test Pin 37/57 at the breakout box and the VPWR pin at the injector vehicle harness connector.
Refer to the Pinpoint Test H Schematic for the appropriate injector pin identification.
Measure resistance between the injector test pin(s) at the breakout box and the same injector circuit signal pin at the each injector vehicle harness connector.
Is each resistance less than 5.0 ohms?
Yes GO to HA10
No SERVICE open circuit. REMOVE breakout box. RECONNECT PCM and injectors.
DRIVE vehicle 5 miles/55 mph.
RERUN Quick Test .
HA10 CHECK INJECTOR HARNESS CIRCUIT FOR SHORT TO POWER OR GROUND
Key off.
Breakout box installed, PCM disconnected.
Suspect fuel injector vehicle harness disconnected.
Refer to the Pinpoint Test H Schematic for the appropriate injector pin identification.
Measure resistance between the injector test pin(s) and Test Pins 37/57, 40, 46 and 60 at the breakout box.
Measure resistance between the injector test pin(s) at the breakout box and chassis ground.
Is each resistance greater than 10,000 ohms?
Yes
For SFI: REPLACE injector per Cylinder Balance DTM fault code. RERUN Quick Test
For MFI: GO to HA11
NO SERVICE short circuit. REMOVE breakout box. RECONNECT PCM and injectors. DRIVE vehicle 5 miles/55 mph. RERUN Quick Test
HA11 ISOLATE FAULTY INJECTOR CIRCUIT
Key off.
Breakout box installed, PCM disconnected.
Disconnect all injectors on suspect bank.
DVOM on 200 ohm scale.
Connect one injector and measure resistance between Test Pin 37 and either Test Pin 58 or 59, as appropriate.
Disconnect that injector and repeat process for each of the remaining injectors.
Refer to Injector Resistance Specification Table 2 .
Is each resistance within specification for the appropriate engine?
Yes GO to HA12
No REPLACE injector. REMOVE breakout box. RECONNECT PCM and injectors. DRIVE vehicle 5 miles/55 mph. RERUN Quick Test
HA12 CHECK INJECTOR DRIVER SIGNAL
Requires standard non-powered 12 volt test lamp.
Key off.
Breakout box installed.
Connect PCM to breakout box.
For MFI:
Connect test lamp between Test Pin 37 and Test Pin 58 at the breakout box.
Connect test lamp between Test Pin 37 and 59 at the breakout box.
For SFI:
Connect test lamp between Test Pin 37 and the suspect injectors Test Pin at the breakout box.
Crank or start engine.
Note: Properly operating systems will show a dim glow on the lamp.
Is glow on lamp dim?
Yes REMOVE breakout box. RECONNECT PCM. Follow instructions of the injector test equipment in Section 9A . Also refer to Ignition Section for other possible causes. After any servicing, DRIVE vehicle 5 miles/55 mph. RERUN Quick Test and Cylinder Balance DTM.
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DTC 185 Mass Air Flow (MAF) lower than expected; your Bronco does not have MAF sensor
