How to Chip a Honda OBD1 ECU

Briansol

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editors note: Originally posted by Adam P and edited for cleanliness.. http://hondaswap.com/~pills/ecuchip.html Saved here in the forums for preservation

USDM OBD1 ECU Chipping

So, you want to chip your obd1 usdm ecu. You didn't listen to me tell you to get a Hondata, or if you did listen and you are reading this... good job. On a scale of 1-10, the difficulty of chipping an ECU is a 3. Just follow these simple instructions and you should be revving past your stock rev limiter using your stock valve train and floating valves in no time, because chances you also didn't listen to me when I told you that your stock cams don't make power over 8000 rpm and your stock valve springs and retainers also can't handle the revs. So sit back, chip your ECU then start looking for new valves.


In order to chip an ECU, you will need the following items:
DCP_1309.JPG

  • de-soldering braid
  • soldering iron
  • talent
  • 28 pin socket
  • 20 pin - 74hc373n chip
  • (insert name of japanese tuner company here) chip / basemap that matches your setup
  • 1.1 kOhm resistor
  • (2) .1 uF capacitors
  • a jumper (just use the end of one of the resistor leads you cut off)
  • soldering flux


obd1_hondata_ecu_chip.JPG


Now for the fun stuff.
  1. De-solder all the holes you will need, so basically read and re-read these instructions before starting. And make sure you use the de-solder braid.
  2. Look at the diagram: 1,2,3 and 4 all require some soldering or de-soldering.
  3. At location 1, solder in the 28 pin socket making sure to keep proper orientation, the notch faces the plug side of the ECU.
  4. At location 2, solder a jumper into J1 and the 1.1 kOhm resistor into R54. (look for the white numbers on the circuit board for the actual locations)
  5. At location 3, solder in the two capacitor at locations C51 and C52.
  6. At location 4, install the 20 pin 74hc373n chip, also with the notch facing the plug side of the ECU.
  7. Make sure the ECU is free of debris and solder pieces, I used that Dust-Off compressed air to clean it up. Apply soldering flux on the areas you soldered as well.

Now install your chip into the socket and replace the ecu in the car (battery disconnected!).

You will likely want to dyno tune the car to ensure your a/f and timing is good with the chip.
 
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