Piggyback Heaven – How To Chip Your Honda ECU

Piggyback Heaven – How To Chip Your Honda ECU


The term “chipping your ecu” is the process of replacing the contents of your ECU/PCM’s ROM with values and tables that you want instead. This will allow you to tune and adjust almost every part of the vehicle’s operation that the ECU governs, from fuel to ignition to more.

The word “chip” comes from the EEPROM chip inside your Honda’s ecu, that you will be flashing or burning a new bin file with the new values you want the ECU to use to run your car. Today we’ll be showing you exactly How To Chip Your Honda ECU.

The tools you will need to chip your ECU :

  • Soldering Iron – So that you can solder the new socket and / or chip into the ECU motherboard
  • Desoldering Iron – So that you can remove the old chip and solder – you can also opt for solder braid
  • ROM Editor – So that you can edit the values held in the ROM chip
  • ROM Burner – Something like a Moates burner that will allow you to make the “flash” changes to the EEPROM


The software that most people use to alter the values in their ECU can range, but most of the “free” solutions like Uberdata, Chrome or Neptune are very easy and straightforward to use. For the sake of this article, we will be lumping in all of these different types of Windows software into “Uberdata” from this point onward to prevent repeating ourselves over and over.

All of the fuel and timing maps in your ECU are stored in a ROM chip (Read Only Memory). Uberdata allows you to program your own ROM chip with custom maps. In order to do this, you need an OBD1 vehicle, and a “chipped” ECU such as the P72, P28, etc etc. This page will explain how to chip your ECU as well as the basic process of burning a ROM chip.

For more information on Uberdata, visit the official site here. There is also a message board there to search for questions that have already been asked and answered by others. For more (a lot more) info on modifying Honda ECU’s in general, visit PGMFi.org.

These are just a few resources available to assist you on your quest to learn How To Chip Your Honda ECU.

ECU Chipping

In order to use Uberdata, you need to add a few additional components to the original Honda ECU. It requires some soldering skills and should not be attempted unless you have soldered before. (Chances are you know someone with soldering skills that could help you). Here is a picture of the P28 ECU that’s been chipped, before any of the parts were put in:


Before you can solder the parts in, you will need to de-solder the holes in the circuit board since they come filled with solder from the factory. You can buy a “solder sucker” to do the job, however unless you get a nice one (expensive) they don’t really work well in my opinion. The cheap and easy solution is to buy some solder braid. It’s just braided copper. Simply place it over the hole to be de-soldered, and place the soldering iron on top of the braid. It will then wick up the solder into the braid.

You’ll want to use a decent quality soldering iron to get the job done nicely. The important thing is to not use too much heat, and also make sure the iron has a fine tip on it. I’m using a standard Weller iron:


Here is what it should look like after the board has been de-soldered:


The parts that need to be added are boxed in with a dashed white line. The parts consist of (2) .1uF ceramic capacitors, (1) 1k resistor, (1) wire jumper (simply a piece of wire…I used a lead of the resistor), (1) 74HC373 chip, and (1) 29C256 chip (thats the EPROM). This part of our How To Chip Your Honda ECU will require you to add onto the board itself.

The resistor and capacitors have no polarity, so you don’t have to worry about installing them backwards. The 74HC373 chip does have a polarity. Pin 1 will be on the left side of the pic (you’ll see in detail later one).

4 honda-crz-04-150x150

The same is true for the EPROM chip. Since it would be impossible to burn a chip and have the tune be perfect, it becomes obvious that you don’t want to solder the chip in. Instead, use a socket so that it can be removed. You have two options: for less than $1, you can get a standard DIP socket. The problem is these are very hard to insert and remove the chips since there are 28 pins (it requires a lot of force and is hard to grip the chip).

Your second option would be a ZIF (Zero Insertion Force) socket, which costs less than $10. It is a socket that has a lever: pull up the lever, set the chip in/lift it out, and flip the lever back – VERY nice to have since you’ll be doing this many times while tuning.

For a primer on How To Dyno Tune your VTEC Honda, or How To Tune Closed Loop Control, check the links from our How To Chip Your Honda ECU.



Be careful when ordering the ZIF socket, as many of them are too large to fit on the board without running into things.


The only problem was that the lever end of it was in the way of the 74HC373. The easy solution is to buy a standard DIP socket as mentioned above. Solder this onto the board. Then, stack the ZIF onto this socket, which raises the ZIF away from the board enough to clear the surrounding parts. This setup worked very well for me. The following picture shows the too-big-to-fit ZIF in the back-left, the low-profile ZIF in the front left, and the DIP socket on the right:

The ZIF socket stacked on the DIP socket for added height:


And finally, a couple of pics with all of the parts installed:


I ordered most of my parts from www.jdr.com except for the low-profile ZIF socket and DIP socket, which I obtained from www.jameco.com.


The following table containse the exact part numbers that I ordered. You’ll notice that I ordered two EPROMS. This way, it will be easier to burn one while the other is installed.

Part Number Quantity Description Source
29C256-12PC 2 This is the chip that you burn with Uberdata JDR
74HC373 1 The other chip that is reqired JDR
R1.0K 1 1K resistor JDR
.1UF 2 .1uF capacitors JDR
102744 1 Low profile ZIF Socket Jameco
40336 1 28 Pin DIP socket Jameco

Additionally, I have recently located all of the parts you will need from one source.DigiKey is where you can find them. Their inventory selection can be overwhelming, so here are the part numbers you will want:

Part Number Quantity Description
AT29C256-70PC-ND 2 This is the chip that you burn with Uberdata
MM74HC373N-ND 1 The other chip that is reqired
1.0KEBK-ND 1 1K resistor
399-2127-ND 2 .1uF capacitors
A347-ND 1 Low profile ZIF Socket
AE7228-ND 1 28 Pin DIP socket

This How To Chip Your Honda ECU Submitted by Kevin Schneider


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