EGR FA?
71, P0401, P0402 Codes from the ECU
Your check engine light is on and you have one of the Codes stored in you ECU.
The EGR is a common problem with the FZJ80. The EGR system lets some exhaust gas, from the exhaust manifold, cycle back into the intake chamber to reduce emissions. This is good for the environment but not good for your motor.
From what I have learned is that the modulator is the big problem. It is a diaphragm that is opened and closed via exhaust gas. It brakes down over time and lets carbon get into the vacuum system. Toyota must of learned that the FZJ80 modulator was faulty as in later years they replaced the modulator with one that was used on the FJ60. If you have the modulator with the green top, replace it with a new one, the blue topped one. Checking several times a year would be a good idea.
These are some tip to get the EGR system working again.
EGR=Exhaust Gas Recirculation
Code 71=EGR System Malfunction
P0401=Exhaust Gas Recirculation Flow Insufficient Detected
P0402=Exhaust Gas Recirculation Flow Excessive Detected.
FSM= Factory Service Manual
ECU= the computer
Red arrow is the modulator.
Green is EGR
After every test, reset the ECU by removing the EFI fuse (in engine bay) for a
several minutes.
1) First check the modulator to see if carbon is in it. If so replace the modulator.
If there was a lot of carbon in there you might need to replace or clean the vacuum hoses.
Take the cap and filter out of the modulator, note how the filter is in there as it needs to go back that way.
If your modulator looks like Darwood’s (below pic) then you indeed need to replace it and clean or replace any contaminated vacuum hoses.
Test the modulator per the FSM
2) If your year has a temperature sensor remove it and clean the tip.
3) Test the VSV per the FSM. The VSV is an electromagnet that opens and closes the vacuum in the vacuum system. If a chunk of carbon gets in the diaphragm it will make the VSV fail. It could if failed once, causing the CE light to come on but then the carbon could of gotten sucked out of it and test ok.
To remove it for the first time it is best to remove the intake chamber as it is tight under there and the screws are tight. Do this when you clean the intake chamber.
4) Test the EGR per the FSM. If your light has been on for a long time carbon could buildup so that the EGR can’t open and close.
5) Clean the intake chamber. The port inside the intake chamber gets plugged with carbon to the point that it is almost plugged. You need to remove the intake chamber to clean it. It cleans up fine with carb. cleaner. Clean the throttle body while you have it off too.
Added Comments from Semlin
1. if you have a 93 not from california you will have no EGR temp sensor which means your EGR system may not throw a code 71/check engine light even if it is not functioning.
2. If you need to remove the EGR valve, the union EGR pipe bolt is a doozy. It is about a 32 or 34 mm bolt and hard to access to get a turn on it. A big wrench may not fit. Robogrips or similar is best. There is also a wire loom right beside the pipe that restricts access where you need it and has been known to break down from heat in the area (mine has some asbestos cladding) You need to be careful not to mangle this loom with the wrench you use as the wires inside may be brittle.
3. you can remove the VSV for EGR without removing the air intake chamber. I just did this two weeks ago, and if I can do it anyone can. You need a 30" extension bar for a 12mm socket to undo one of the screws that holds the vsv assembly on (clearly visible from underneath once you look for it), and then you need either an open 12mm spanner or maybe a box wrench for the other bolt accessed from the ds side under the intake chamber (finicky). The bolts were stiff and had never been removed before on mine but they broke away ok. I found it much easier to remove the whole VSV bracket assembly from the throttle body side of the air intake chamber after removing all the vacuum hoses and switches (and also after removing the throttle body - see next comment). At that point it was easy to remove the bolt holding the vsv to the bracket with an impact screw driver.
4. if your system has not been serviced for a while check every vacuum hose and also the metal tubes too (e.g., the ones on the VSV bracket, and originating from the throttle body). You particularly want to check the hose that runs from the EGR, through the intake chamber and then to the vsv. Blowing through one end will tell you if it is blocked where is passes through the intake chamber.
Here are some pic and there are more posted later in this thread under my name.
71, P0401, P0402 Codes from the ECU
Your check engine light is on and you have one of the Codes stored in you ECU.
The EGR is a common problem with the FZJ80. The EGR system lets some exhaust gas, from the exhaust manifold, cycle back into the intake chamber to reduce emissions. This is good for the environment but not good for your motor.
From what I have learned is that the modulator is the big problem. It is a diaphragm that is opened and closed via exhaust gas. It brakes down over time and lets carbon get into the vacuum system. Toyota must of learned that the FZJ80 modulator was faulty as in later years they replaced the modulator with one that was used on the FJ60. If you have the modulator with the green top, replace it with a new one, the blue topped one. Checking several times a year would be a good idea.
These are some tip to get the EGR system working again.
EGR=Exhaust Gas Recirculation
Code 71=EGR System Malfunction
P0401=Exhaust Gas Recirculation Flow Insufficient Detected
P0402=Exhaust Gas Recirculation Flow Excessive Detected.
FSM= Factory Service Manual
ECU= the computer
Red arrow is the modulator.
Green is EGR
After every test, reset the ECU by removing the EFI fuse (in engine bay) for a
several minutes.
1) First check the modulator to see if carbon is in it. If so replace the modulator.
If there was a lot of carbon in there you might need to replace or clean the vacuum hoses.
Take the cap and filter out of the modulator, note how the filter is in there as it needs to go back that way.
If your modulator looks like Darwood’s (below pic) then you indeed need to replace it and clean or replace any contaminated vacuum hoses.
Test the modulator per the FSM
2) If your year has a temperature sensor remove it and clean the tip.
3) Test the VSV per the FSM. The VSV is an electromagnet that opens and closes the vacuum in the vacuum system. If a chunk of carbon gets in the diaphragm it will make the VSV fail. It could if failed once, causing the CE light to come on but then the carbon could of gotten sucked out of it and test ok.
To remove it for the first time it is best to remove the intake chamber as it is tight under there and the screws are tight. Do this when you clean the intake chamber.
4) Test the EGR per the FSM. If your light has been on for a long time carbon could buildup so that the EGR can’t open and close.
5) Clean the intake chamber. The port inside the intake chamber gets plugged with carbon to the point that it is almost plugged. You need to remove the intake chamber to clean it. It cleans up fine with carb. cleaner. Clean the throttle body while you have it off too.
Added Comments from Semlin
1. if you have a 93 not from california you will have no EGR temp sensor which means your EGR system may not throw a code 71/check engine light even if it is not functioning.
2. If you need to remove the EGR valve, the union EGR pipe bolt is a doozy. It is about a 32 or 34 mm bolt and hard to access to get a turn on it. A big wrench may not fit. Robogrips or similar is best. There is also a wire loom right beside the pipe that restricts access where you need it and has been known to break down from heat in the area (mine has some asbestos cladding) You need to be careful not to mangle this loom with the wrench you use as the wires inside may be brittle.
3. you can remove the VSV for EGR without removing the air intake chamber. I just did this two weeks ago, and if I can do it anyone can. You need a 30" extension bar for a 12mm socket to undo one of the screws that holds the vsv assembly on (clearly visible from underneath once you look for it), and then you need either an open 12mm spanner or maybe a box wrench for the other bolt accessed from the ds side under the intake chamber (finicky). The bolts were stiff and had never been removed before on mine but they broke away ok. I found it much easier to remove the whole VSV bracket assembly from the throttle body side of the air intake chamber after removing all the vacuum hoses and switches (and also after removing the throttle body - see next comment). At that point it was easy to remove the bolt holding the vsv to the bracket with an impact screw driver.
4. if your system has not been serviced for a while check every vacuum hose and also the metal tubes too (e.g., the ones on the VSV bracket, and originating from the throttle body). You particularly want to check the hose that runs from the EGR, through the intake chamber and then to the vsv. Blowing through one end will tell you if it is blocked where is passes through the intake chamber.
Here are some pic and there are more posted later in this thread under my name.
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