Adapting an EJ20G ECU
Posted: Wed May 12, 2010 9:02 pm
Hi all,
I thought it would be good idea to capture all that is required to adapt a JDM WRX EJ20G ecu to a stock ej22t.
There are five areas that need to be addressed;
*ECU wiring changes
*Ignition changes
*Injector changes
*Fuel Pump changes
*MAF changes
Each are described separately below;
ECU RELATED CHANGES
----- DE-PIN FROM CONNECTOR ------
- Purge Control (F47-6 ; White-Blue) :: Remove from the ECU plug. Purge control does not exist on the JDM EJ20G ECU. This pin is used for the 5th injector control on the WRX RAs (although it not used on any stock ECU). I am not sure what the consequence will be of losing control of the purge system.
- California Pin (B56-11 ; Green-Black) :: Remove from the ECU plug. This pin is used for the JDM EJ20G accelerator pedal switch. It has no impact on the behavior of the EJ20G ECU.
----- DE-PIN AND MERGE WITH ANOTHER ------
- MAP ground (B48-5 ; Red) :: Merge with B48-21. B48-5 is used for the stock JDM EJ20G cat efficiency EGT sensor. Not having an the stock EGT sensor has zero impact on how the ECU runs. The EJ20G harness combines the MAP sensor ground with all other sensor grounds at B48-21.
----- OTHER ECU DIFFERENCES THAT CAN BE IGNORED ------
- N/A (F47-4) :: Nothing to be done. On the EJ20G ECU, this is the Fan #2 control.
- N/A (F47-16) :: Nothing to be done. On the EJ20G ECU, this is the steering pressure switch input.
- N/A (F48-12) :: Nothing to be done. On the EJ20G ECU, this is for the EGT cat efficiency warning light.
- TPS shield (B58-7 ; Black) :: Nothing to be done. On the EJ20G ECU this pin is unpopulated in the connector. TPS shield it is located at B48-21, but B58-7 will work as well as both pins are connected inside the ECU.
----- MOUNTING ------
The mounting between the two ECUS is quite difference. What I did to make it fit is basically use the top half of the EJ20G case and the bottom half of the EJ22T case and fit them together.
Here is the stock EJ20G ECU;
Remove the six screws from the side. These are fairly soft material and threadlocked in. Its very easy to strip out if you do not use the proper size phillips head. If they do strip, then it's out with the vise grips!
Once off you have access to the ECU board.
Remove the two screws that hold the ECU down to the bottom half of the case. Then put the board back in the top half and use the two matching screw locations to reattach to the case.
Lastly, take the bottom half of the EJ22t has ears on either side that can be fitted around the edges of the top half. This provides a pretty snug fit. I wasn't so thrilled that the ECU board wasn't as secure and possible susceptible to vibration, so I jammed a bunch of bubble wrap between the bottom of the board and the bottom half of the case. Sounds ghetto, but it works the treat! Lastly to make sure the two halves didn't want to pop apart I put a little duct tape around the seam.
Viola!
IGNITION CHANGE
The EJ22T ignition system is a 2 channel "wasted spark" setup with an external coil pack and an external 2 channel igniter. The ECU sends out two alternating trigger signals to the igniter. Each of those causes the coil to fire on one of the two pairs of cylinders. The cylinders are paired to the coil such that the spark arrives on the compression of one and the exhaust stroke of the other.
The EJ20G setup is for is a four channel coil on plug (COP). There are four coils each of which are molded to the sparkplug boots are physically located in the spark plug wells. Each coil has two wires, +B and the output of the igniter. Each coil pack is grounded through the mounting bolts to the head. There is a 4-channel external igniter that outputs to the individual coils and also takes as input four trigger signals from the ECU.
To boil it down, the EJ20G ECU will send out four igniter triggers, each 90deg apart when the EJ22T igner is expecting two 180deg apart. It is not possible to simply plug the EJ20G ECU into the EJ22t harness and expect the ignition system to just work.
The two approaches to resolve this are:
1) Either to use EJ20G coils/igniter and adding the necessary wires to the harness. This is only an option if your engine uses different heads; EJ20G, EJ20H, EJ20R, and EJ25D are all known to work. Technically this is the best option and made even better if you skip the EJ20G components and go directly to the GD COP conversion. You can check out my coil conversion thread on Nasioc Besides the coils being superior to the older G coils, This route makes install a bit easier as it completely eliminates the need for the external igniter and the associated wiring. One would only need to run the four wires from the ECU pins directly to each coil, a common +B wire to all the coils (most likely from the +B wire from the removed EJ22T coil pack), and a grounding ring from the coils to the mounting bolt.
2) Modify the igniter trigger signal output from the EJ20G ECU to look like the equivalent 2-ch signal and keep the rest of the EJ22T ignition system intact. The easiest solution is to use my 4to2 converter box that does exactly this. It is relatively simple to install and is smart enough to run both ECUs without removal or modification. Follow the link above for more info.
PhyrraM has a real good write-up of how to use two seperate igniters to achieve the same result.
INJECTOR CHANGE
Match the injectors with the tune. Stock EJ20G uses grey top 450cc/min injectors. They are drop in compatible with the EJ22T rails.
http://bbs.legacycentral.org/viewtopic. ... +injectors
If you are running my "550" tune you would use yellow side feed injectors from an '04+ STi (or LGT/OBX/FXT from the same vintage) which technically flow 525cc/min but are commonly incorrectly referred to as 550cc injectors. These require EJ22 NA rails or EJ22T rails with adapters.
http://bbs.legacycentral.org/viewtopic. ... +injectors
http://bbs.legacycentral.org/viewtopic. ... +injectors
These are NOT to be confused with the yellow side feed injectors from the EJ20K JDM STi motors. Those are 480cc/min and fit the same as the grey top injectors.
FUEL PUMP CHANGE
You will need to match the FP to the uprated injectors. '04+ STi fuel pumps, Walbro 195 or 255 are common choices.
MAF CHANGE
You will need to match the MAF to the ECU. If you are using the stock EJ20G ECU, then match it to Subaru part 22680AA160. This is also referred to simply as a JECS MAF or a green label MAF; both for obvious reasons. The good news here is that these are simply plug and play. They fit the same physically and electrically as the stock EJ22T MAF. The other bit of good news is that they are very common parts, so they are cheap and easy to find. Here is a list of the models that used this MAF; http://opposedforces.com/parts/info/22680AA160/.
I thought it would be good idea to capture all that is required to adapt a JDM WRX EJ20G ecu to a stock ej22t.
There are five areas that need to be addressed;
*ECU wiring changes
*Ignition changes
*Injector changes
*Fuel Pump changes
*MAF changes
Each are described separately below;
ECU RELATED CHANGES
----- DE-PIN FROM CONNECTOR ------
- Purge Control (F47-6 ; White-Blue) :: Remove from the ECU plug. Purge control does not exist on the JDM EJ20G ECU. This pin is used for the 5th injector control on the WRX RAs (although it not used on any stock ECU). I am not sure what the consequence will be of losing control of the purge system.
- California Pin (B56-11 ; Green-Black) :: Remove from the ECU plug. This pin is used for the JDM EJ20G accelerator pedal switch. It has no impact on the behavior of the EJ20G ECU.
----- DE-PIN AND MERGE WITH ANOTHER ------
- MAP ground (B48-5 ; Red) :: Merge with B48-21. B48-5 is used for the stock JDM EJ20G cat efficiency EGT sensor. Not having an the stock EGT sensor has zero impact on how the ECU runs. The EJ20G harness combines the MAP sensor ground with all other sensor grounds at B48-21.
----- OTHER ECU DIFFERENCES THAT CAN BE IGNORED ------
- N/A (F47-4) :: Nothing to be done. On the EJ20G ECU, this is the Fan #2 control.
- N/A (F47-16) :: Nothing to be done. On the EJ20G ECU, this is the steering pressure switch input.
- N/A (F48-12) :: Nothing to be done. On the EJ20G ECU, this is for the EGT cat efficiency warning light.
- TPS shield (B58-7 ; Black) :: Nothing to be done. On the EJ20G ECU this pin is unpopulated in the connector. TPS shield it is located at B48-21, but B58-7 will work as well as both pins are connected inside the ECU.
----- MOUNTING ------
The mounting between the two ECUS is quite difference. What I did to make it fit is basically use the top half of the EJ20G case and the bottom half of the EJ22T case and fit them together.
Here is the stock EJ20G ECU;
Remove the six screws from the side. These are fairly soft material and threadlocked in. Its very easy to strip out if you do not use the proper size phillips head. If they do strip, then it's out with the vise grips!
Once off you have access to the ECU board.
Remove the two screws that hold the ECU down to the bottom half of the case. Then put the board back in the top half and use the two matching screw locations to reattach to the case.
Lastly, take the bottom half of the EJ22t has ears on either side that can be fitted around the edges of the top half. This provides a pretty snug fit. I wasn't so thrilled that the ECU board wasn't as secure and possible susceptible to vibration, so I jammed a bunch of bubble wrap between the bottom of the board and the bottom half of the case. Sounds ghetto, but it works the treat! Lastly to make sure the two halves didn't want to pop apart I put a little duct tape around the seam.
Viola!
IGNITION CHANGE
The EJ22T ignition system is a 2 channel "wasted spark" setup with an external coil pack and an external 2 channel igniter. The ECU sends out two alternating trigger signals to the igniter. Each of those causes the coil to fire on one of the two pairs of cylinders. The cylinders are paired to the coil such that the spark arrives on the compression of one and the exhaust stroke of the other.
The EJ20G setup is for is a four channel coil on plug (COP). There are four coils each of which are molded to the sparkplug boots are physically located in the spark plug wells. Each coil has two wires, +B and the output of the igniter. Each coil pack is grounded through the mounting bolts to the head. There is a 4-channel external igniter that outputs to the individual coils and also takes as input four trigger signals from the ECU.
To boil it down, the EJ20G ECU will send out four igniter triggers, each 90deg apart when the EJ22T igner is expecting two 180deg apart. It is not possible to simply plug the EJ20G ECU into the EJ22t harness and expect the ignition system to just work.
The two approaches to resolve this are:
1) Either to use EJ20G coils/igniter and adding the necessary wires to the harness. This is only an option if your engine uses different heads; EJ20G, EJ20H, EJ20R, and EJ25D are all known to work. Technically this is the best option and made even better if you skip the EJ20G components and go directly to the GD COP conversion. You can check out my coil conversion thread on Nasioc Besides the coils being superior to the older G coils, This route makes install a bit easier as it completely eliminates the need for the external igniter and the associated wiring. One would only need to run the four wires from the ECU pins directly to each coil, a common +B wire to all the coils (most likely from the +B wire from the removed EJ22T coil pack), and a grounding ring from the coils to the mounting bolt.
2) Modify the igniter trigger signal output from the EJ20G ECU to look like the equivalent 2-ch signal and keep the rest of the EJ22T ignition system intact. The easiest solution is to use my 4to2 converter box that does exactly this. It is relatively simple to install and is smart enough to run both ECUs without removal or modification. Follow the link above for more info.
PhyrraM has a real good write-up of how to use two seperate igniters to achieve the same result.
INJECTOR CHANGE
Match the injectors with the tune. Stock EJ20G uses grey top 450cc/min injectors. They are drop in compatible with the EJ22T rails.
http://bbs.legacycentral.org/viewtopic. ... +injectors
If you are running my "550" tune you would use yellow side feed injectors from an '04+ STi (or LGT/OBX/FXT from the same vintage) which technically flow 525cc/min but are commonly incorrectly referred to as 550cc injectors. These require EJ22 NA rails or EJ22T rails with adapters.
http://bbs.legacycentral.org/viewtopic. ... +injectors
http://bbs.legacycentral.org/viewtopic. ... +injectors
These are NOT to be confused with the yellow side feed injectors from the EJ20K JDM STi motors. Those are 480cc/min and fit the same as the grey top injectors.
FUEL PUMP CHANGE
You will need to match the FP to the uprated injectors. '04+ STi fuel pumps, Walbro 195 or 255 are common choices.
MAF CHANGE
You will need to match the MAF to the ECU. If you are using the stock EJ20G ECU, then match it to Subaru part 22680AA160. This is also referred to simply as a JECS MAF or a green label MAF; both for obvious reasons. The good news here is that these are simply plug and play. They fit the same physically and electrically as the stock EJ22T MAF. The other bit of good news is that they are very common parts, so they are cheap and easy to find. Here is a list of the models that used this MAF; http://opposedforces.com/parts/info/22680AA160/.