Yo,
121 &122
TPS Overview & Testing; "...The TPS is a three wire sensor that measures the throttle plate opening and its rate of change. This sensor is a variable resistor, also called a potentiometer, that is directly linked to the throttle plate shaft. The TPS outputs a voltage directly proportional to the throttle opening. As the accelerator is depressed the throttle plate opens and the TPS voltage increases. The TPS assists the PCM in determining transmission shift points, converter lock-up and along with the MAP and MAF sensor are main PCM indicators of acceleration and load. In other words, the PCM looks at these sensors to calculate engine operation upon acceleration. Let me preface by saying I do not believe that any Ford TPS requires adjustment unless you have played with your Throttle Plate Set ***** or have a performance application. The procedure is not mentioned in any Ford Factory or Engine, Emissions-Diagnosis Manual that I have seen. If you require an Adjustable TPS you must set it just below 1v, ideally between 0.96v-0.98v. This is because the PCM is programmed to observe the TPS Signal Voltage in three modes: Idle Mode, Less than 1v. Part Throttle Mode, Greater than 1v. WOT Mode, Greater than 3.7v (Breakpoint is Plus 2.7v). The 0.96v-0.98v. setting has been determined to be optimal as it minimizes time delay between Closed Throttle and Part Throttle which increases performance. This is where general TPS Adjustment Settings Instructions are directed and many mistakenly think it is all inclusive. The shop modification of drilling out the ***** holes for additional adjustment is directed at people that use the incorrect TPS or cannot achieve the setting parameters due to intentional Throttle Body variences. On the other hand, EEC-IV Broncos use a Non-Adjustable TPS. Each time the key is turned on the PCM reads the Closed Throttle TPS voltage and places it in KAM memory as TPREL PID (or Ratch) Voltage. Ratch Voltage then becomes the baseline for Idle where the PCM assumes 0% Throttle Opening. The PCM is programmed for a voltage stairstep, (or Ratch), to Part Throttle and Wide Open Throttle (WOT) values. These stairstep values are based on the initial Closed Throttle readings and are determined each time the ignition key activates the PCM and TPS. Ratch Values: Closed Throttle, Initial Voltage Setting. Part Throttle, +0.02v above Closed Throttle. Wide Open Throttle, +2.71v above Closed Throttle. Even though the PCM determines Ratch Voltage with key on, there are different vehicle specifications for TPS Settings. This is to ensure that your TPS can operate within the full range of it's mechanical/electrical capability (In the case of my 1990 5.8L Bronco, this range is 0.34v-4.84v between 0-85 degrees rotation). As long as your settings are within the factory specified range, such as listed below, your TPS will be correct. TPS Settings: 1990 Bronco 4.9L - 0.73v to 1.22v. 1990 Bronco 5.0L - 0.73v to 1.22v. 1990 Bronco 5.8L - 0.73v to 1.22v. 1995 Bronco 4.9L - 0.65v to 1.28v. 1995 Bronco 5.0L - 0.65v to 1.28v. 1995 Bronco 5.8L - 0.65v to 1.28v. In either case, the PCM generally operates in Open loop on cold Start-up, Closed-Loop on warm idle/low-load cruising and Open-Loop during WOT. Open-Loop refers to shutting down the EGR, ignoring O2, ECT, ACT Sensor Input and relying upon programmed fuel maps. The TPS is advising the PCM through throttle modes when to go into Open or Close Loop Operations. And, as the TPS is an electrical/mechanical device, the TPS Sensor can wear out by developing dead spots which cause idle problems or hesitation usually in the most used lower range. Finally, Curb Idle and Fast Idle are controlled by the PCM and IAC and are not adjustable. This means adjusting your Throttle Plate Set ***** from the factory calibration will not allow the IAC to effectively control the rpm. This changes the Throttle Plate position potentially causing it to stick in the bore and it alters the TPS settings by either telling the PCM that you are always at Part Throttle or pushing it outside of setting specification. The Throttle Body Return ***** adjusts the Throttle Plate for Minimum Air Rate, which is the minimum amount of air required to maintain idle with the IAC unplugged. Plug the IAC in and the PCM is in control of your Idle. This means that you should not have to touch the Throttle Plate Set ***** unless someone has played with it or if you have a performance application which requires a higher Idle air flow. That is where you must adjust your TPS back to factory settings to compensate for the change in Throttle Plate position. As the Minimum Air Rate, Engine Load, TPS Sensor and the IAC are very closely linked, they must all work together to maintain a good idle. Idle problems can be caused by a myriad of other issues which should always be looked at first. These include ignition, fuel, spark, EGR,vacuum and PCV to name a few. Then the KOEO TPS Harness may be tested for Reference Voltage. The KOEO TPS Voltage may be back probed for baseline setting and a smooth increase thoughout the Throttle rotation. The unplugged TPS Sensor may be tested for Resistance also throughout the Throttle rotation. KOEO TPS Testing: KOEO TPS Reference Voltage, 5v (VREF/SIG RTN). KOEO TPS Signal Voltage, Less than 1v to 4.5v (TP SIG/SIG RTN while rotating Throttle). Unplugged TPS Resistance, Less than 4k ohms, Greater than 350 ohms (TP SIG/SIG RTN while rotating Throttle)..."
Source: by Seattle FSB (SeattleFSB) at FSB
http://www.fullsizebronco.com/forum/blogs/seattle-fsb/681-throttle-position-sensor-management.html
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128 indicates the MAP sensor vacuum has not changed more than 2 in-Hg (7 kPa) during normal vehicle operation.
Possible causes:
MAP sensor vacuum supply hose improper routing, blockage and/or linkage.
MAP sensor leak.
•Key off.
•Check vacuum hoses for proper routing. Refer to VECI decal. Check MAP sensor vacuum supply hoses for disconnections, kinks or blockage.
Are vacuum hoses OK?
read more at
http://www.thedieselstop.com/faq/9497faq/maint/vra/vra06022.htm#pptdf11
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DTC 41, 42, 91, 92, 136, 137,139, 144, 171, 172, 173, 175, 176, 177 & some Possible Causes for Rich & Lean HEGO The engine temperature must be greater than 50°F (10°C) to pass the KOEO Self-Test and greater than 180°F (82°C) to pass the KOER Self-Test. To accomplish this, the engine should be at normal operating temperature
Source: by Ryan M (Fireguy50)
DTC 172 lean Heated O2; "...Backprobe the MAF (+) and MAF-RTN (-) lines with a DVOM. You should see ~1.0V or slightly less at warm idle. If not, check the +12V and GND lines to make sure there's battery voltage between those terminals with the ignition key turned ON. You also may want to try using the proper spray cleaner on the MAF wires, especially if you have a K&N oily filter (in which case I can almost guarantee there's oily junk on your MAF's wires). Also make certain that the tube(s) leading from the MAF to the throttle body are 100% intact. The red wire (on the right in the first above picture) is supposed to have battery voltage with the key on. Measure between that wire and the one right next to it. You measure the MAF voltage at idle, because the MAF voltage is what's interpreted by the PCM..."
Source: by SigEpBlue (Steve)
DTC 172, 173 or 41 for HO2S Failure Or Fuse \"E\" Inoperative, ABS Light On, Back-Up Lamps Inoperative, Daytime Running Lamp (DRL) Inoperative, MIL On, Inadvertent Self-Test, Speedometer Inoperative & Trailer Battery Charge Relay Inoperative in TSB 95-5-21 for 92-95 Bronco & F Series; "...the HO2S wires in the 12A690 (subassembly of the 14B060 battery cable) harness may become chafed and the vehicle could exhibit any one of the following conditions....Lack of proper HEGO operation may cause, or be the result of a rich or lean fuel condition, which could cause additional heat in the catalyst. Perform self test KOEO and KOER, service any codes. CHECK FOR PROPER HEGO GROUND. If the HEGO ground is good, the following areas may be at fault: ..." READ MORE
Source: by Ford via Steve
http://api.viglink.com/api/click?format=go&jsonp=vglnk_146861476483511&key=6ed47b392b9edfe394b9e89b72717104&libId=iqo78r1501000bgv000MAbcnv3fdb&loc=http%3A%2F%2Fwww.fullsizebronco.com%2Fforum%2F7-1980-96-bronco-tech%2F420577-dtcs-found-advise-procedure-please.html&v=1&out=http%3A%2F%2Fwww.supermotors.net%2Fregistry%2Fmedia%2F646262&ref=https%3A%2F%2Fwww.google.com%2F&title=DTCs%20found...advise%20on%20procedure%20please%20-%20Ford%20Bronco%20Forum&txt=1983%20Ford%20Bronco%20TSBs%20%26amp%3B%20FSAs%20(Recalls)%20for%20%2783-96%20Broncos%20%26amp%3B%20F150s%20picture%20%7C%20SuperMotors.net
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DTC 411 Idle speed system not controlling idle properly (generally idle too high); "...DTC 411 indicates a dirty/ bad or connector issue w/ Idle Air Control valve (IAC). inspect it for crapola. Some can be cleaned. But our's shouldn't since the TSB says; "...Cleaning is not required on sludge tolerant throttle body designs released for 1991 and newer model years...." in Idle Air Control (IAC) Sludge; Poor Idle TSB 91-25-07 for 85-92 Bronco & F Series & many others; "...Hard cold starts, hesitation and stalls on initial start-up or during idle or decel may be caused by sludge in the throttle body and/or idle by-pass valve. Sludge deposits or oil film on the throttle body bore and plate or the idle air by-pass valve may cause one or more of the following conditions. Hard Cold Start, Stall On Initial Start-Up, Stall During Idle, Stall During Decel, Rough Idle, Rolling Idle, Hesitation During Acceleration. A new idle air by-pass service kit (F2PZ-9F939-A) is now available for service use to correct sludge contamination concerns of the throttle bore and plate only. It eliminates the need to clean the majority of past model throttle body applications. Cleaning is not required on sludge tolerant throttle body designs released for 1991 and newer model years..."
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DTC 412 Cannot control RPM during KOER self-test high RPM check. \"...indicates that during the Engine Running Self-Test, engine rpm could not be controlled within the Self-Test upper limit band. Possible causes: Open or shorted circuit. Throttle linkage binding. Improper idle airflow set. Idle Air Control (IAC) solenoid contamination. Items external to Idle Air Control system that could affect engine rpm. Damaged IAC solenoid. Damaged Powertrain Control Module (PCM). Turn the key \"OFF\", connect a tachometer. Then start the engine and disconnect the Idle Air Control (IAC) harness connector. Does the rpm drop or engine stall? If it does, turn the key \"OFF\" and disconnect the IAC. With an Digital Volt/Ohm Meter (DVOM) check the resistance of the IAC solenoid. It should be between 6.0 and 13.0 ohms. Due to diode in the solenoid, place the DVOM (+) lead on the VPWR pin and the (-) lead on the IAC pin. If it is not within specification, replace the IAC solenoid..." miesk5 Note; Ford says the range is 7-13 ohms
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DTC 538 Insufficient RPM change during dynamic response test. "...This is another code generated when the dynamic response or "goose" test as some refer to it is not performed during the KOER test. The KOER test requires that after a certain length of time the throttle be opened to bring the idle above 2000 rpm for a short period of time. If the dynamic response test is not performed or the rpm's do not peak ABOVE 2000 rpm's this code will be generated. (Computer needs to compare changes in sensor readings at different RPM's to determine system operation and efficiency)..." IGNORE this DTC FOR NOW
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DTC 536 - Brake On/Off circuit failure / switch not actuated during KOER test or shorted to ground. IGNORE this DTC if brake pedal was not ppressed during self test
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DDTC 632 - OD cancel switch not changing state. "...During the KOER test, AFTER the initial recognition code is generated, the brake pedal must be applied, the OD switch must be turned off and then back on and finally the "goose" test must be performed. This code is generated when the person performing the KOER test fails to deactivate and reactivate the OD cancel switch at the end of the shift lever. It does NOT indicate a problem unless the switch WAS INDEED deactivated and reactivated and the code still came up. (Computer needs to know if the tranny is in OD or not)..."
IGNORE this DTC if OD switch was not activated aand ...
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633 4x4L switch should be in 4×2 or 4×4 high for the self test
