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19 Posts
Discussion Starter #1
So I've pretty much did all the searching I can and can't find someone with a similar problem as me and its kinda haunted me for quite some time now. Usually after it warms up, you can see and feel the idle hunting, and while it's running you can hear hear it miss. In addition to that, when driving down the road, when I hit 4th gear, and reach 2100 rpm the tranny will start shifting hard, BUT only if I hit 2100 rpm in 4TH gear! Another thing that's weird is that if it's really cold out and the bronco hasn't been ran, it's run fine!

Another thing that puzzles me a bit, is usually when I'm in 4th gear I can run 60 mph and be at 1800rpm, now it's running 2100 Rpm at 40-55mph?
I've tried parts swapping but my wallet is hurting,
Replaced tps, iac, coil, plugs, plugs wires, inspected the cap, cleaned all the tranny connections, all the shops are puzzled by it

Super Moderator
26,076 Posts
YO Cam;

See replies to your Q at

Try a Self Test for Diagnostic Trouble Codes (DTC)s by my pal, BroncoJoe19
A helper is good to assist in reading Codes; best is to take a cell fone vid and replay it.
Some basics;
Visual Check
1.Inspect the air cleaner and inlet ducting.
2.Check all engine vacuum hoses for damage, leaks, cracks, blockage, proper routing, etc.
3.Check EEC system wiring harness for proper connections, bent or broken pins, corrosion, loose wires, proper routing, etc.
4.Check the Powertrain Control Module (PCM), sensors and actuators for physical damage; IAC, TPS I see was replaced, etc.5.Check the engine coolant for proper level and mixture.
6.Check the transmission fluid level and quality. See E4OD Fluid Condition Check Below)
7.Make all necessary repairs before continuing
8. Check headlights

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 including Reverse.

Make sure A/C is off and transmission is in Park (automatic); or in Neutral for a Manual & release clutch.

Turn off all accessories; radio, lights, A/C, heater, blower, fans, etc. (close driver's door)

Then turn off engine and wait 10 seconds.

Do KOEO test First

Post Code(s) here according to:

The Self-Test is divided into three specialized tests: Key On Engine Off Self-Test, Engine Running Self-Test, and Continuous Self-Test. The Self-Test is not a conclusive test by itself, but is used as a part of the functional Quick-Test diagnostic procedure. The PCM stores the Self-Test program in permanent memory. When activated, Self-Test checks the EEC system by testing memory integrity and processing capability, and verifies that various sensors and actuators are connected and operating properly.

The Key On Engine Off and Engine Running Self-Tests are functional tests which only detect faults present at the time of the Self-Test. Continuous Self-Test is performed during normal vehicle operation and stores any fault information in Keep Alive Memory (KAM) for retrieval at a later time.

Key On Engine Off Self-Test
At this time, a test of the EEC system is conducted with power applied and engine at rest.
To detect errors during Key On Engine Off Self-Test, the fault must be present at the time of testing.

Continuous Memory DTCs are issued as a result of information stored during Continuous Self-Test, while the vehicle was in normal operation. These DTCs are displayed only during Key On Engine Off Self-Test and after the separator pulse. Intermittent faults that have not occurred in the last 80 warm-up cycles (40 cycles on some applications) are erased from Continuous Memory and will not produce a Continuous Memory DTC.Note: The separator pulse and Continuous Memory DTCs follow Key On Engine Off DTCs ONLY.

Engine Running Self-Test
At this time, a test of the EEC system is conducted with the engine running. The sensors are checked under actual operating conditions and at normal operating temperatures. The actuators are exercised and checked for expected results.

E4OD Fluid Condition Check
It should be red, not brown or black. Odor may indicate overheating condition, clutch disc or band failure.
Use an absorbent white facial tissue and wipe the fluid level indicator. Examine the stain for evidence of solid particles and for engine coolant signs (gum or varnish on fluid level indicator).
If particles are present in the fluid or there is evidence of engine coolant or water, the transmission pan must be removed for further inspection.
If fluid contamination or transmission failure is confirmed by further evidence of coolant or excessive particles in the transmission pan, the transmission must be disassembled and completely cleaned and serviced. This includes cleaning and flushing the torque converter and transmission cooling system. Repair or replace radiator.
During disassembly and assembly, all overhaul checks and adjustments of clearances and end play must be made.
After the transmission has been serviced, all diagnostic tests and adjustments listed in the Diagnosis by Symptom Charts under Diagnosis by Symptom in the Diagnosis and Testing portion of this section must be completed to make sure that the problem has been corrected.
btw, I'll begin with describing the commonly used erm "limp mode" first, then get to Ford's description.

If all the shifts are hard, PCM is going into limp mode that causes E4OD to shift hard because the pressures are increased.
PCM goes into limp mode when it senses an error in the transmission shifting or electrical system.
The most common cause for this is the Manual Lever Position (MLPS) also called Transmission Range (TR) Sensor. This is the sensor that is bolted to the drivers side of the transmission case with the shift lever arm going through the center of the sensor.
Try disconnecting the battery for 15 minutes with the headlamps on. This should clear the limp mode and return the transmission to normal shift strategy. If it does then the problem is intermittent.
If it still shifts hard then the fault is continuously occurring. It is possible that there is another input/output signal problem, but 99% of the time it is the MLPS/TR sensor especially if it clears limp mode proving the problem is intermittent.

happens when the vehicle computer recognizes a problem in it's logic. When an expected signal value from a sensor is sent to the computer and is not within the computer's programmed specifications, "secondary" programs are activated by the computer to strive to protect the transmission from damage the improper sensor signal might cause to occur.

In other words, the computer is always expecting certain signal values from certain sensors i.e. the temperature sensor, the speed sensor, the throttle position sensor, etc. As long as these signals are what it would normally expect for the conditions and is normal based on all the other signals it is receiving from other sensors, it acts normally and accordingly.

If the computer, all of a sudden, receives some crazy signal from one of the sensors that is out of the normal range expected from this sensor, it will go to "emergency" or "secondary" measures.

These emergency measures vary depending on the severity of the defective signal. All this is preprogrammed into the computer's logic by the manufacturer. The manufacturer has decided that as long as a certain parameter of a particular signal is sent from a sensor to the computer, all is well. The manufacturer decided that if this signal is higher than their highest parameter or lower than their lowest parameter, something is wrong with that sensor and the computer should make someone aware of the situation and take action to try to "save" the vehicle systems or powertrain.

Perhaps the computer will simply cause the "check engine" light to come on. The signal variation wasn't severe or critical to cause any mechanical failures but the vehicle's operator is made aware that he or she should have the vehicle checked out electronically to see if a minor sensor has broken down or is starting to send the odd erratic signal. This type of condition is commonly referred to as a "soft code". Normal functions are not affected but if the repair is not made, performance or fuel efficiencies might suffer. Perhaps the sensor only malfunctioned one time and all other times was fine. This might be an early warning of a sensor that is beginning to fail or has a loose connector or connection.

Other times the signal needed to perform operations normally is so far out of specification that the computer has no choice but to go into survival mode. With transmissions, the computer will cause the internal tranny fluid line pressure to default to high to protect clutches and bands. The transmission also turns off the shift solenoids to cause the unit to default to a single gear, usually second or third. All normal instructions to control line pressure are overridden so a hazardous "slipping condition" cannot occur easily. This theoretically is so that the vehicle's driver can get the damaged vehicle to the next town for repairs. This condition is commonly called "Limp Mode" for this reason. You limp to the next town in second or third gear only, at full line pressure so the tranny guts won't slip on your trip in.

By the way, interestingly and just as a side note, if the cable harness going to your transmission was ever to become detached, severed or damaged, your transmission would also go to "limp mode".
miesk5 note; check it on passenger side of trans.

E4OD solenoid body connector seating by SeattleFSB
The vehicle's computer would immediately sense that it has lost contact with the transmission and would set the codes and send "limp mode" signals to the tranny. But because the harness is severed between the computer and the transmission, no computer signals will reach the transmission. These sent signals, however, would have had the identical affect on the transmission as what taking away supplied power to the shift and line pressure solenoids has as in the case of a transmission harness being detached or cut. Due to the engineered voltage strategies of the solenoids, the transmission simply defaults to a single gear and line pressure defaults to high, all in order to "limp" you home.

A Throttle Position Sensor that improperly sends a reading that it is wide open when in fact it is physically closed would be detected by the computer when it compared this reading with the vehicle speed sensor that perhaps is showing very slow vehicle speed. The signal, by itself can't be considered wrong but when put against all the other sensor signals of the system might cause a computer concern. The computer, at this point, unable to "trust" the collection of signals because together they are not making sense in it's logic, will simply go to limp mode in the transmission to protect it and make the operator aware that something is wrong with one of the sensors and a mechanic's attention is needed to correct the situation.

Source: by Greg O at via

19 Posts
Discussion Starter #3
Thanks miesk5! Really good info! Well I tried pulling codes and didn't find any, replaced my spark plugs cause I read Bosch platinums are horrible for this truck, deff smoothed out the idle. Changed my trans fluid and filter, fluid looked like it needed changing. Test drove it on the interstate at 75mph(NO HARD SHIFTING!!!) 15 mins later... Hard shifting returned, it's like it only does it on the interstate

19 Posts
Discussion Starter #5
So I rewired the new mlps, still does the same thing, so I decided to check voltages again, tps came up short, traced it to the power distribution box, still low voltage. So I decided to see what the computer looks like cause I've heard of them going bad from time to time, I found this

22 Posts
My truck is doing the same thing because the torque converter is failing. I was going into limp mode only in certain instances on the highway and had higher than normal RPMs at lower speeds. I was getting a code 628 you should be able to retrieve some sort of code if it is going in to limp mode. Maybe try to check again?

19 Posts
Discussion Starter #9
It only throws the code 628 when in limp mode, if I don't take it on the highway it won't throw that code. I've lve also heard that if your truck has been in limp mode for awhile it could cause torque converter damage resulting in the code 628
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