As I have worked on my fj62 over the past few months, it has become apparent to me that a single reference thread with info and links to other pertinent threads would be useful for trouble shooting 3FE engine problems—especially for guys like me where this is my first foray into the exciting and at first intimidating world of EFI.
My thinking is to have a good starting point with references to other threads where a 3FE or EFI problem was resolved. So there should be a problem defined, and a resolution summary at the end.
I don’t claim any authority on the subject. My degree is in electronics, and my career started out in repairing complex test and measurement systems. I started back in the day of washing machine sized disk drives that could store a whopping 300 MB of data. These old girls had lots of adjustments, and gave lots of chances to troubleshoot weird electromechanical problems. These were delicate devices that took delicate tools to repair them. The torque wrenches I used were calibrated in inch pounds! Mechanically, I was raised by the world’s greatest shade tree mechanic, so any automotive mechanical skills I have, I learned in the trenches. Working on my 3FE has been an interesting blend of my professional electronics background and my amateur mechanical skills—limited as they may be.
I thought I would first start off with a bit of a primer (as I understand it) taken from a couple of sources including the FSM and the Landcruiser section of the Toyota 1988 New Car Features Manual.
EFI technology is a happy melding of electronics and mechanics. There are multiple sensors in and around the 3FE engine that monitor different operating aspects of the engine. These sensors can detect things like how much air is coming into the engine as well as how clean the fuel air mixture is being burned. All of these sensors are wired to the Electronic Control Unit (ECU), which is the brain of the whole operation. Based on the sensor readings, the ECU can adjust air/fuel mixture, spark advance, and even fuel pressure. The ECU controls these functions through the use of Actuators. Some of these actuators include fuel injectors and the igniter. In order to trouble shoot these devices—the sensors and the actuators—you need a good Multimeter (measures voltage, current and resistance). I prefer a digital mutimeter, known as a DMM. You also need to know how to use it, and you need to learn how to read a schematic diagram. All the schematics in the FSM are pretty simple, so once you learn the schematic symbols for resistors, relays, switches and light bulbs, you are well on your way. You will also need to understand the relationship of voltage, current and resistance as described by Ohms law.
The cool thing about having a computer control the engine is that as you travel from cold to hot, or low to high, the ECU adjusts engine parameters so that the engine is running at peak performance in all conditions. Having a computer control the engine gives us another cool feature—it can often tell us what is wrong with the engine! After all, if a sensor or actuator is not functioning correctly, the ECU should be the first to know. The ECU used in our Landcruisers is a fairly primitive one by todays standards, and we don’t need a fancy device to read the error codes. On the firewall in the engine compartment is a connector with a cap on it. Pop the cap, and connect two of the connections together with a short piece of wire, and the Check Engine light in the dash becomes a trouble shooting tool as it flashes any error codes. In theory, if there is an error detected by the ECU, the check engine light should stay on to alert us to the need to check for an error, but I have learned that there can be error codes in the ECU that don’t turn on the check engine light. So check for error codes every time you change the oil, and definitely start any 3FE troubleshooting with a quick check for error codes.
Here are a couple of diagram’s of the sensors and actuators monitored and controlled by the ECU and their locations:
My thinking is to have a good starting point with references to other threads where a 3FE or EFI problem was resolved. So there should be a problem defined, and a resolution summary at the end.
I don’t claim any authority on the subject. My degree is in electronics, and my career started out in repairing complex test and measurement systems. I started back in the day of washing machine sized disk drives that could store a whopping 300 MB of data. These old girls had lots of adjustments, and gave lots of chances to troubleshoot weird electromechanical problems. These were delicate devices that took delicate tools to repair them. The torque wrenches I used were calibrated in inch pounds! Mechanically, I was raised by the world’s greatest shade tree mechanic, so any automotive mechanical skills I have, I learned in the trenches. Working on my 3FE has been an interesting blend of my professional electronics background and my amateur mechanical skills—limited as they may be.
I thought I would first start off with a bit of a primer (as I understand it) taken from a couple of sources including the FSM and the Landcruiser section of the Toyota 1988 New Car Features Manual.
EFI technology is a happy melding of electronics and mechanics. There are multiple sensors in and around the 3FE engine that monitor different operating aspects of the engine. These sensors can detect things like how much air is coming into the engine as well as how clean the fuel air mixture is being burned. All of these sensors are wired to the Electronic Control Unit (ECU), which is the brain of the whole operation. Based on the sensor readings, the ECU can adjust air/fuel mixture, spark advance, and even fuel pressure. The ECU controls these functions through the use of Actuators. Some of these actuators include fuel injectors and the igniter. In order to trouble shoot these devices—the sensors and the actuators—you need a good Multimeter (measures voltage, current and resistance). I prefer a digital mutimeter, known as a DMM. You also need to know how to use it, and you need to learn how to read a schematic diagram. All the schematics in the FSM are pretty simple, so once you learn the schematic symbols for resistors, relays, switches and light bulbs, you are well on your way. You will also need to understand the relationship of voltage, current and resistance as described by Ohms law.
The cool thing about having a computer control the engine is that as you travel from cold to hot, or low to high, the ECU adjusts engine parameters so that the engine is running at peak performance in all conditions. Having a computer control the engine gives us another cool feature—it can often tell us what is wrong with the engine! After all, if a sensor or actuator is not functioning correctly, the ECU should be the first to know. The ECU used in our Landcruisers is a fairly primitive one by todays standards, and we don’t need a fancy device to read the error codes. On the firewall in the engine compartment is a connector with a cap on it. Pop the cap, and connect two of the connections together with a short piece of wire, and the Check Engine light in the dash becomes a trouble shooting tool as it flashes any error codes. In theory, if there is an error detected by the ECU, the check engine light should stay on to alert us to the need to check for an error, but I have learned that there can be error codes in the ECU that don’t turn on the check engine light. So check for error codes every time you change the oil, and definitely start any 3FE troubleshooting with a quick check for error codes.
Here are a couple of diagram’s of the sensors and actuators monitored and controlled by the ECU and their locations:
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