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75 Posts
Discussion Starter #1
Some back info...

Changed out the distributor, cap, rotor, wireset, plugs gap correctly, fuel filter, TPS, ignition coil, O2 sensor, PCV, and cleaned the IAC.

All this was done when the head gaskets got replaced and it had a full once over. for the last week or so Ive had a loss of power and a mis that you can feel in natural and wile driving.

Pulled some codes and this is what i got....


ok so here is how they came or what i think it was... 23,23,1,22,62,63,2,1,62,63



Plx help thanks guys:whiteflag

Super Moderator
26,097 Posts
yo York,
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 Screw 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 screw 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 Screw 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 Screw 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 Screw 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

"...Symptoms of a BAD TPS: The one thing that you can definitely count on, when the TPS fails, is the Check Engine Light shining nice and bright to let you know that there's a Diagnostic Trouble Code stored in the Fuel Injection Computer. Here are some specific symptoms you'll see:
TPS Diagnostic Trouble Codes (DTC’s) stored in the vehicle’s computer’s memory.
Code 23: Throttle Position (TP) Circuit Performance Problem.
Code 63: Throttle Position (TP) Circuit Low Input.
Really BAD gas mileage.
No power as you accelerate the vehicle.
Hesitation when you step on the Accelerator Pedal.
Source: by

DTC 63 in KOEO Throttle Position Sensor (TPS) below minimum 0.6 volts. Suspect open TP sensor, or grounded, check harness
DTC 63 in KOER TPS ckt has intermittently failed below minimum 0.6 volts
DH4 CHECK VREF CIRCUIT VOLTAGE; Key off. l TP sensor disconnected. Key on, engine off. Measure voltage between VREF circuit and SIG RTN circuit at the TP sensor vehicle harness connector. Is voltage between 4.0 and 6.0 volts?
Yes, REPLACE TP sensor. RERUN Quick Test.
No, Key off. RECONNECT all components. GO to Pinpoint Test Step C1.

C1 CHECK VEHICLE BATTERY POWER CIRCUIT; Key off. Disconnect Powertrain Control Module (PCM). Inspect for damaged or pushed out pins, corrosion, loose wires, etc. Service as necessary. Install breakout box and connect PCM to breakout box. Key on, engine off. Measure voltage between Test Pin 37 at the breakout box and SIG RTN circuit in the Data Link Connector (DLC). Note voltage. Measure voltage across battery terminals. Note voltage. Are both voltages greater than 10.5 volts, and are both voltages within 1.0 volt of each other?
Yes, GO to C2. No Key Off, RECONNECT sensor (if applicable).
GO to B1

I don't have the B2 nor C2, yet.

BOB test pins numbers are most often same as EEC pins numbers
VREF is a conditioned regulated constant 4-6v power source supplied by the PCM.
battery voltage can vary from 12 to 15 volts
SENSORS; SIG-RTN GY-R is EECIV PIN 46. VREF BR-W is Pin 26 ; MAP LG-BK is Pin 45

DTC 22/126 indicates the Manifold Absolute Pressure (MAP) sensor is out of Self-Test range. Correct MAP/BARO range of measurement is typically from 1.4 to 1.6 volts.
Do NOT use an ordinary voltmeter to check a Ford BP/MAP sensor because doing so can damage the electronics inside the sensor. This type of sensor can only be diagnosed with a DVOM that displays frequency, or a scope or scan tool
Also make sure engine manifold vacuum is within specifications at idle. If vacuum is unusually low due to a vacuum leak, retarded ignition timing, an exhaust restriction (clogged converter), or an EGR leak (EGR valve not closing at idle).
A low intake vacuum reading or excessive backpressure in the exhaust system can trick the MAP sensor into indicating there is a load on the engine. This may result in a rich fuel condition.
A restriction in the air intake (such as a plugged air filter), on the other hand, may produce higher than normal vacuum readings. This would result in a load low indication from the MAP sensor and possibly a lean fuel condition.

A good MAP sensor should read barometric air pressure when the key is turned on before the engine starts. This value can be read on a scan tool and should be compared to the actual barometric pressure reading to see if they match. Your local weather channel or website should be able to tell you the current barometric pressure reading.
Check the sensor's vacuum hose for kinks or leaks. Then use a hand-held vacuum pump to check the sensor itself for leaks. The sensor should hold vacuum. Any leakage calls for replacement.
An outright failure of the MAP sensor, loss of the sensor signal due to a wiring problem, or a sensor signal that is outside the normal voltage or frequency range will usually set a diagnostic trouble code (DTC) and turn on the Check Engine light
"...The vacuum gauge should show 18-22 in-Hg @ idle, and 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)..."
Source: by SigEpBlue (Steve) at FSB

Possible causes:
circuit open between sensor vehicle harness connector and PCM.
circuit shorted to VREF, SIG RTN, or GND.
Damaged MAP sensor.
Vacuum trapped at MAP/BARO sensor.
Unusually high/low barometric pressure.
Kinked or obstructed vacuum lines (MAP).
Basic engine (valves, vacuum leaks, timing, EGR valve, etc.).
High atmospheric pressure.
Damaged PCM.
VREF circuit open at MAP sensor.
SIG RTN circuit open at MAP sensor.

The pinpoint test directs you to check the voltage to the MAP sensor. With the MAP sensor connected, use paper clips to back probe the MAP connector so you make contact with the terminals inside the connector by inserting the paper clips into the bak of the connector. This allows you to get voltage readings while the connector is plugged in. The other option is to use straight pins to pierce the insulation of the wires. First check the voltage of the outer two wires of the MAP connector by connecting a voltmeter to the clips or pins you have inserted. You should see 5 volts with the key on. This is the power to the sensor.

The BLK/WHTwire provides a ground called Signal Return (SIG RTN on EEC), it will show 0 volts with the black probe on negative battery terminal. The 5 volts VREF (ON EEC) (Reference Voltage) is supplied on the ORG/White wire. The Signal the computer reads is on the middle wire, DK BLUE/-Lt GRN (MAP on EEC). The correct MAP/BARO range of measurement is typically from 1.4 to 1.6 volts on the Signal (middle wire).

If any of the voltages are out of range, there is a wiring problem that needs to be tracked down and repaired. These three wires all go back to the computer. The signal wire (middle) is the only one not shared by other sensors, it goes straight to the computer. The Signal Return and VREF are also provided to other sensors

Wiring Diagram in a 90 5.0 & 5.8


DTC 62, 628 and/or 1728 Transmission Shifts Hard TSB 98-4-19 in 90-96 Bronco


64 KOER - Intake Air Temp (IAT); (Air Charge Temperature [ACT] prior to 1992) has intermittently failed below 0.2 volts.

DTC 64 Intake Air Temp (IAT)/ (Air Charge Temperature (ACT) prior to 1992); sensor out of range (signal voltage too low), sensor is bad/dirty or wiring is grounded
Source: by miesk5 at FSB
Location Diagram & Depiction in 87-91 (from Factory Manual and the Ford Electrical & Vacuum Troubleshooting Manual (EVTM)
Source: by Broncobill78 (Dave) at
Cleaning w/Carburetor Cleaner in a 90 5.0; "...also noticed the intake air temperature (IAT) sensor was reading on the cool side, compared with the ambient air temp, so I pulled the sensor out of the intake and found Figure 5: a dirty IAT. I cleaned it with some spray carb cleaner and the truck passed the emissions test!..." miesk5 NOTE; site won't allow you to return to this page
Source: by Brian M at asa
65 KOER - Overdrive OFF switch was not cycled during KOER test (user error).

75 Posts
Discussion Starter #4
Used a multimeter and traced the TPS signal all the way to the bulkhead for the EEC its still getting full signal so its not a wire issue. could a bad EEC be the issue? would the truck still run with a bad EEC? if the EEC is getting the signal why is it throwing TPS codes?

2,625 Posts
1.3V sounds a little high for the "closed" voltage on the TPS. Above, in miesk5's post, he has stated that the specified range for the 1990 5.8 is 0.73-1.22V. You stated you're at 1.3V. Did you engage the "prongs" on the TPS correctly with the throttle blade peg?

Also, some of those other codes are for the E4OD tranny. They pop when the tranny electronics are acting up.

My $0.02,

75 Posts
Discussion Starter #6
I used a T pin to back probe the connector at the TPS. I know that a little high but the difference between 1.2 and 1.3 volts seems to be such a little amount to cause this many problems i could be totally wrong here though

75 Posts
Discussion Starter #7
Switched out the new TPS with a stock Ford one and all the TPS codes are gone then was able to properly adjust the base timing and that almost all but took away the miss a lot of the power is back and it runs smoother but It still has a slight problem so I pulled out the EEc and found both blue capacitors are leaking and one was broken off on one leg not even sure how its still running or what the job of the 2 blue caps are but I'm thinking I need to go get a new EEc
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