FAQ : How to Install Hondata S300 Into Virgin P28 ECU... 56k no way


5+ Year Member
First off yes i know i posted this in the EG forum But i know not everyone in the forced induction Forum views the EG board. So i thought i would share this write up with you guys.

Ok today im showing you how to install Hondata S300 Into your OBDI ECU.

BTW You can check out more of my Write ups on my website at. Http://JDMLyfeStyle.com

before we get started i have to get this out of the way.

This is a Tru DIY. Not everyone has a Expensive Desoldering station. so Dont hate when i do these write ups. This is for the Real DIY guys on a budget

Also do not copy any of my images or copy this write up to any other website without my consent. I monitor all my bandwith and see where it goes.

Warning attempt this at your own risk. I am not responsible if you damage your ecu or car in any way. I am not liable for your Mistakes. By doing this you do know that you are messing with the computer that operates your car. if you mess up in any way you may cause damage to your Vehicle. Once again attempt this at your own risk. if you dont feel you can do this leave it to the professionals.

This ECU was chipped according to the Hondata Instructions.

Tools that are needed for this project are:

1. A Hondata S300 Unit
2. P28 ECU
3. Soldering Iron
4. Solder
5. Desoldering braid
6. Dremel with cutting disc
7. Phillips Head Screw Driver
8. Pen or Sharpie marker
9. Magnifying glass

Ok Now to the write up

Step 1. Remove the 5 Screws on the top side of the ecu as labeled in the picture

Step 2. Remove the 5 Screws on the bottom side of the ECU.

Step 3. Look at the front of the ECU. see where the ECU plugs are and there is a screw to the right. Loosen that screw.

Step 4. Remove the 7 screws holding the ECU board to the casing. Some may not like this step but i prefer it for easier access.

Step 5. Gently Remove the ECU board from the cage. Now you will be left with the ECU in 4 parts. the top cover, bottom cover, case, and ECU board. Be sure the ECU board is placed on a Very Very Clean Spot.

Step 6. Ok now turn on your soldering iron. Some dont have adjustable temperatures. mine does. Im use to my 650 degree setting. Also be sure your Sponge is wet!

Step 7 Ok now when you look at the ECU board this is what you are going to see. Now look at the 2nd picture the area's Highlighted in Red are the area's that we will be working in.

Step 8 Now its time to get to work. Look at the area on the board. you can loacate the CN2 in the lower left hand of the picture. Take your Desoldering braid and Lay it over the CN2 part of the board. the place the soldering iron on each of the solder'd spots. wait til all the solder is soaked up and you should be left with a hole.

Step 9 Ok Now take your 4 head pin. and place it so that it is in the board. CN2-1 thru CN2-4. So on the CN2 board it should be like this. XXXXO ... the O is showing that it is still empty and nothing is installed into it. Now once the 4 pin is installed into the slots. then flip the board over and solder the 4pin to the board. Be sure not to burn any of the tracks and do not allow the solder to connect the 4 pins together. There should be a space between each pin.

Step 10. IF your ECU was previously Chipped Skip this step. Now move Over to the 74HC373 location on the board. if you are having trouble finding it refer to the pix above on the highlighted areas. Now desolder all 20 spots on the board. now it should look like this.

Step 11. Place the Chip that was provided by Hondata into the 74HC373 spot that was just Desolder'd. Be sure that the Notch is facing towards the ECU plugs. Then just flip over the board and solder in the chip. be sure that u do not connect any of the solder joints.

Step 12. Ok Now its time to move Over onto the 27256 Spot. Now you need to desolder the 28 pins. If your ECU has a ZIF socket installed already then once it is desolder'd remove the ZIF

Step 13. Now take the 2 14 pin Male Heads and install them into the board. The short part goes through the board. Once there in place then Solder them to the board. Be sure not to connect the solder joint.

Step 14. Look right above the 27256 spot you just finished up on. You should see the J1 location, R54 Location. Desolder both of these locations.

Step 15 Now place a the resistor provied with the Hondata kit in the R54 spot. Then take a Piece of thin wire or solid line and place it into the J1 spot. If you ever want to return to the stock program you will need to cut the j1 jumper.

Step 16 Ok Now its time to move to the Last spot on the board. Locate the J12 Jumper. Take and desolder that location and remove the jumper so that its just 2 holes sitting there. this needs to be removed so that you can datalog properly.

Step 17 Now place the ECU board back into the ECU case. and just install 4 screws to hold the board to the case. DO NOT install the top or bottom covers.

Step 18 Line up the 4 pin socket on the S300 unit and once you get the tips of the pins into the socket. then the 28 pin should line up as well. GENTLY press the hondata unit onto the pins.

Step 19 Now if you look there is no possible way to connect the Hondata to a laptop. We have to cut a hole in the side of the ECU. So grab your pen or marker and mark the area around where the USB goes.

Step 20 Now remove the ECU board out of the case by removing the screws. You dont want metal or debri getting onto the ECU.

Step 21 Grab your dremel and cut out where you marked. and be sure to leave some play so the cord can move without rubbing the metal.

Step 22. Now Put the ECU board back in and Put all the screws back in place. then put on the top and bottom covers on and be sure to tighten the screw on the front of the ECU by the plugs. I went ahead and made a Clear ECU cover cause i just like the look and i like to see whats on the inside.



La Raza #2
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WOW...nice write up...just found this thread looking for hondata info..should be sticked on the How to's???


Set This World On Blaze!!
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wow i need to get the usb dat logger for mine. Thats awesome.


What's up dogz!!!
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how much willbe the s300?