FirstExplorer
Well-Known Member
- Joined
- May 14, 2010
- Messages
- 109
- Reaction score
- 17
- City, State
- Flower Mound, Texas
- Year, Model & Trim Level
- 1991 XLT 4WD
I am the original owner of my 1991 Ford Explorer XLT 4X4. It has been one of the best vehicles I have owned, and I have kept it very well maintained.
But, I have searched through this forum and have seen numerous owners with similar poor performance, low mileage, pinging and knocking under load, needing premium gas, etc. The threads usually direct the troubleshooting to 5-6 areas which usually do not correct the problem.
Question for the experts:
Could all these problems be traced to a bad Engine Control Module (ECM)? This little primitive computer regulates all the problem areas I mentioned. I have found references on the internet that the early ECMs were junk, and that there are good replacements that even have better chips, memory, and performance tweeks.
The following is a lot to read, but I cut and pasted a passage from and ECM supplier website, and I think it explains it pretty well:
ECU ECM PCM
The Electronic Control Unit (ECU), Electronic Control Module (ECM), Power Control Module (PCM)
The ECM/ECU controls the fuel injection system, ignition timing, and the idle speed control system. When needed for power transfer or safety measures, the ECM/ECU also interrupts the operation of the air conditioning and initiates idle surge when sensing braking in automatic transmission vehicles. ECM's/ECUs control EGR systems and initiates voltage reference signal power to the fuel pump (through the control relay) for start up. The basic model ECM/ECU consists of an 8-bit microprocessor, random access memory (RAM), read only memory (ROM), and an input/output interface.
Also referred to as the "BRAIN BOX" the ECM/ECU is the central processor unit of the vehicles ignition, power and electrical systems. Based on information from the input sensors (crank angle (when applicable), throttle position, engine coolant temperature, air flow, etc.), the ECM/ECU determines optimum settings for the output actuators (ignition timing, injection, idle speed, etc.).
ECM FAILURE: FACT OR FICTION
If you have a car manufactured between 1985-2002, OBD-I and OBD-II, your engine management system ECM(s) and body control computers may have a higher propensity for failure and may fail eventually. This is likely due to several factors including the mounting and location of the units, and a critical implementation and utilization of internal components that have proved to have inherent intolerance to heat. "Normal" usage included the mounting location of the units which often meant the components in over 100F temperature sometimes. The current through the lands of the units also led to many problems that have been occurring separately and some indirectly affecting other controllers with adverse affects. Some components often will intermittently loose there ability to function properly such as storing a voltage charge for future use or providing a clean voltage signal for proper operation. Eventually they can lead to other fatal malfunctions of other components including injectors, coils, actuators which can in turn be another diagnostic nightmare. These components were used by the millions in hundreds of applications by among others: Mitsubishi, Lexus, Toyota, Honda, Acura, Ford, OKI, Kefico, Cummins, Detroit Diesel, Allison & CAT in the manufacturing of their ECMs.
So the fact is there is a huge problem, BUT it can and must be addressed or you could be one of millions who have been paying too much for diagnosis & repair or living with a malfunctioning vehicle engine management system and or engine diagnostic system. All the units must be retrofitted with higher rated and stronger components and the damage must be cleaned and continuity and flow restored and sometimes reprogramming must be done. Without this the ECU can not function at optimum level for fuel and emission factors, and the main diagnostic tool, the ECU cannot be relied on for diagnostic data.
But, I have searched through this forum and have seen numerous owners with similar poor performance, low mileage, pinging and knocking under load, needing premium gas, etc. The threads usually direct the troubleshooting to 5-6 areas which usually do not correct the problem.
Question for the experts:
Could all these problems be traced to a bad Engine Control Module (ECM)? This little primitive computer regulates all the problem areas I mentioned. I have found references on the internet that the early ECMs were junk, and that there are good replacements that even have better chips, memory, and performance tweeks.
The following is a lot to read, but I cut and pasted a passage from and ECM supplier website, and I think it explains it pretty well:
ECU ECM PCM
The Electronic Control Unit (ECU), Electronic Control Module (ECM), Power Control Module (PCM)
The ECM/ECU controls the fuel injection system, ignition timing, and the idle speed control system. When needed for power transfer or safety measures, the ECM/ECU also interrupts the operation of the air conditioning and initiates idle surge when sensing braking in automatic transmission vehicles. ECM's/ECUs control EGR systems and initiates voltage reference signal power to the fuel pump (through the control relay) for start up. The basic model ECM/ECU consists of an 8-bit microprocessor, random access memory (RAM), read only memory (ROM), and an input/output interface.
Also referred to as the "BRAIN BOX" the ECM/ECU is the central processor unit of the vehicles ignition, power and electrical systems. Based on information from the input sensors (crank angle (when applicable), throttle position, engine coolant temperature, air flow, etc.), the ECM/ECU determines optimum settings for the output actuators (ignition timing, injection, idle speed, etc.).
ECM FAILURE: FACT OR FICTION
If you have a car manufactured between 1985-2002, OBD-I and OBD-II, your engine management system ECM(s) and body control computers may have a higher propensity for failure and may fail eventually. This is likely due to several factors including the mounting and location of the units, and a critical implementation and utilization of internal components that have proved to have inherent intolerance to heat. "Normal" usage included the mounting location of the units which often meant the components in over 100F temperature sometimes. The current through the lands of the units also led to many problems that have been occurring separately and some indirectly affecting other controllers with adverse affects. Some components often will intermittently loose there ability to function properly such as storing a voltage charge for future use or providing a clean voltage signal for proper operation. Eventually they can lead to other fatal malfunctions of other components including injectors, coils, actuators which can in turn be another diagnostic nightmare. These components were used by the millions in hundreds of applications by among others: Mitsubishi, Lexus, Toyota, Honda, Acura, Ford, OKI, Kefico, Cummins, Detroit Diesel, Allison & CAT in the manufacturing of their ECMs.
So the fact is there is a huge problem, BUT it can and must be addressed or you could be one of millions who have been paying too much for diagnosis & repair or living with a malfunctioning vehicle engine management system and or engine diagnostic system. All the units must be retrofitted with higher rated and stronger components and the damage must be cleaned and continuity and flow restored and sometimes reprogramming must be done. Without this the ECU can not function at optimum level for fuel and emission factors, and the main diagnostic tool, the ECU cannot be relied on for diagnostic data.
