There is no driveability memory. It's all in your heads. Diesels do not do that, and Ford didn't do it with the diesel trans until the TorqShift. Those are the facts, believe it or not.

The KAM in the 7.3L diesels stores error codes. That's it.

 

Casey, that's troubling news to me. Not that I doubt what you are saying, but it seems odd to me. I've had a long list of Ford gassers all with adaptive strategy that I could manipulate at times when needed. What is your source of this information? All computer controlled engines operate off of a code/table consisting of: if this then that type strategy. Are you saying the PSD does not have this? Certainly it has to or no PCM would be needed.
Again, not trying to start in with you but you've got me stumped here. I do remember the old speed density type engines the mustangs had that were severely limited in their adjustments/adaptabilty compared to the mass air systems that followed. Is this the type of system that we've been hobbled with in our 15 year later trucks? Basically an algorythmm that goes like if this then that, if outside of parameters then nothing?
On a side note, I know our trucks are limited in the PCM to tranny communication area basically by researching chips/tuners. The newer 6.blows allow tuning of the transmission through software whereas we have to get tranny kits. So I believe you may be onto something, just wondering what your source is. Thanks.

 

The PCm does use the same type of look up tables as other vehicles. What it can't do is change the values by what it sees on a feedback loop.

No diesel has a feedback loop. Not the 7.3 and not the 6.0. All diesels run lean any time that they are not making black smoke, and if they are stock they never make black smoke. Since they are always lean an O2 sensor will always read lean, so there is no O2 sensor in a diesel, and therefor no feedback loop.

On the trans, the TorqShift, and most gasser trans, will look at the time that a shift takes to complete. If it's too long it adds pressure to the lookup table for next time the trans makes that shift. If the shift is too short it removes pressure from that lookup table for the next shift.

On the 4R100 behind the 7.3 there was no software that added or removed pressure based on how long the previous shift took. If you did a 1-2 shift at 50% throttle you always got the same pressure to the clutch. On the gas engine version of the 4R100 it would add or remove pressure based on shift length. For whatever reason they never added this code to the diesel version.

 

So it's the lack of a feedback loop then. Hmm, No wonder a chip or a tuner makes such a big gain over the same item when used in a gasser application. I wonder how they overcome this feedback loop problem? I guess they simply have a modified table with more aggressive injector timing and duration tables.
Thanks.

 

I believe some of the ships do that, and some of the add on boxes modify the signals coming in from the sensors to trick the PCM into delivering more fuel.

 

Casey, I guess then I am loosing my mind. I have been told that "It's in your head" before, so that is not the first time.

I am going to check with my local FORD mech regarding the drivability memory. I have not talked with him lately. He was the one who told me to disconnect the cables and let it sit for a while. Maybe there was a code set that was holding it back and the disconnect erased the code.

Also, there is the possibility that when the wife drives it, as slow as she drives, a sensor (soot fouling) that is failing may set the code and then when I start lead footing it, the sensor clears/cleans up and it is ok again.

 

He may tell you the opposite of what I told you. Then who are you going to believe?

Many mechanics believe that there is learning on the 7.3L diesel modules. That doesn't make it true.

 

Casey, I am not doubting you, but I called my mech and then call the zone rep for backup.

You are right. You will definately get some points for that one.

Hey moderator, you can now close this debate!

 

Casey, I did doubt you because I just couldn't believe that in this day and age that the PCM would be of such a primitive design. Another opportunity lost by Ford. Very disappointing. Just wondering how you knew this when most like myself assumed that it could learn, or at least be more adaptable to driver style based on all those inputs.

 

That's just one of life's mysteries....

 

OK Casey, let us in on this. How did you find out?

 

2001 PCED OBD II Diesel SECTION 1: Description and Operation
Procedure revision date: 10/02/2002

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Diesel Powertrain Control Software

Multiplexing
The increased number of modules on the vehicle dictate a more efficient method of communication. Multiplexing is the process of communicating several messages over the same signal path. This process allows multiple modules to communicate with each other through the signal path (BUS+/BUS-). Modules communicate with the Powertrain Control Module using Standard Corporate Protocol (SCP) which determines the priority in which the signals are sent. (Refer to Standard Corporate Protocol for more information.)


Standard Corporate Protocol
The Standard Corporate Protocol (SCP) is a communication language used by Ford Motor Company for exchanging bi-directional messages (signals) between stand-alone modules and devices. Two or more signals can be sent over one circuit.

Included in these messages is diagnostic data that is output over the BUS + and BUS - lines to the Data Link Connector (DLC). This information is accessible with a scan tool. Information on this equipment is described in Section 2 , Diagnostic Methods.


Flash Electrically Erasable Programmable Read Only Memory
The Flash Electrically Erasable Programmable Read Only Memory (FEEPROM) is an Integrated Circuit (IC) within the PCM. This integrated circuit contains the software code required by the PCM to control the powertrain. One feature of the FEEPROM is that it can be electrically erased and then reprogrammed without removing the PCM from the vehicle. If a software change is required to the PCM, the module no longer needs to be replaced, but can be reprogrammed at the dealership through the Worldwide Diagnostic System (WDS) or New Generation STAR (NGS) Tester. The reprogramming is done through the DLC.


Failure Mode Effects Management
Failure Mode Effects Management (FMEM) is an alternate system strategy in the PCM designed to maintain vehicle operation if one or more sensor inputs fail.

When a sensor input is perceived to be out-of-limits by the PCM, an alternative strategy is initiated. The PCM substitutes a fixed value and continues to monitor the incorrect sensor input. If the suspect sensor operates within limits, the PCM returns to the normal engine running strategy.

FMEM operation will result in Continuous Memory DTCs during normal engine operation and when performing Key On Engine Running Self-Test Mode.


Engine RPM Limiter
The Powertrain Control Module (PCM) limits engine rpm by cutting off fuel whenever an engine rpm overspeed (3500 rpm) condition is detected. RPM limits are as follows:

F-Series 250/550, E-Series, and Excursion — 3500
F-Series 650/750 with automatic transmission — 2850
F-Series 650/750 with manual transmission — 2750
The purpose of the engine rpm limiter is to prevent damage to the powertrain.


Vehicle Speed Limiter
Note: Maximum speed may vary with load and axle ratio.

For F250-550 applications, a diesel engine equipped vehicle is limited to a maximum speed of approximately 150 km/h (95 mph). For F650/750 applications, the maximum vehicle speed is approximately 90 km/h (60 mph). For E150/450, the maximum vehicle speed is approximately 160 km/h (100 mph).


Powertrain Control Module
The center of the Electronic EC system is a microprocessor called the Powertrain Control Module (PCM). The PCM has a 104-pin electrical connector. The PCM receives input from sensors and other electronic components (switches, relays, etc.) and places this information in RAM or Keep Alive RAM. Based on information programmed into its memory (ROM), the PCM generates output signals to control various relays, solenoids and actuators.


Keep Alive Random Access Memory (RAM)
The PCM stores information in Keep Alive RAM (a memory integrated circuit chip) about vehicle operating conditions, and then uses this information to compensate for component variability. Keep Alive RAM remains powered when the vehicle key is off so that this information is not lost.

Power and Ground Signals
Vehicle Power
When the key is turned to the start or run position, battery positive voltage (B+) is applied to the coil of the Electronic EC Power Relay. Since the other end of the coil is wired to ground, this energizes the coil and closes the contacts of the Electronic EC Power Relay. Vehicle power (VPWR) is now sent to the PCM and the Electronic EC System as VPWR.

Vehicle Reference Voltage
The Vehicle Reference Voltage (VREF) is a positive voltage (about 5.0 volts) that is output by the PCM. This is a consistent voltage that is used by the three-wire sensors.

Signal Return
The Signal Return (SIG RTN) is a dedicated ground circuit used by most Electronic EC sensors and some other inputs.

Power Ground
Power Ground (PWR GND) is an electric current path return for VPWR voltage circuit. The purpose of the PWR GND is to maintain sufficient voltage at the PCM.

Gold-Plated Pins
Some engine control hardware components have gold-plated pins on the connectors and mating harness connectors to improve electrical stability for low draw current circuits and to enhance corrosion resistance. The Electronic EC components equipped with gold terminals will vary by vehicle application.

Note: Damaged gold terminals should only be replaced with new gold terminals.

------------------------------------

Not wanting to start a debate or anything. Just curious as to why the RAM section of the service manual says what it says if that is not what is happening?

 

Not everything Ford publishes is 100% correct. That is a good generic description, but the 7.3L/4R100 is an exception. I guess they chose not to spell out the exception.

 

Keep Alive Random Access Memory (RAM)
The PCM stores information in Keep Alive RAM (a memory integrated circuit chip) about vehicle operating conditions, and then uses this information to compensate for component variability. Keep Alive RAM remains powered when the vehicle key is off so that this information is not lost.

Great stuff Scott. There appears to be some hope, but evidently not much. I don't think there's a whole lot going on in the KAM. I could be wrong, I guess it just depends on how much it compensates and what components sensors it compensates for. Good to know it does adjust something.

 

C'mon Casey. Tell us the source of your info. Otherwise this thread will continue in the KAM!!! We could get stuck in an error loop if we don't get evidentiary sensor input from you. Then we'll all be in limp mode.