626/MX6/MX3/323/X6/X9/Ford Probe 91-95 ECU REMAP – Part 1 – Chipping the ECU.

The mazda K series V6 engines still live and will continue to live as they are pretty stout and reliable engines.. These good sounding engines also deliver good power to the wheels but.. We, car enthusiast, always crawl for more power. What if we want more power? of course if you have a 1.8 Liter V6 engine (K8, K8-DE, K8-ZE) the best solution would be an engine swap to a KL-DE (KLDE) or KL-ZE (KLZE) but if you already have a 2.5 Liter engine or you wish to stay 1.8 you can have a solution: Remap your ECU. To remap your ECU, you need to “chip” an Obd1 ECU.

First of all, i want to say THANKS to Alexander Moskalev from Moscow since his hard work on these ECU is what made the remapping possible. He, I believe before anyone else, reverse engineered those ecu to locate the parameters we can today adjust. Further research has been done by me thanks to my friend Antonio who provided me the car to work on.

While the gains are somewhat limited compared to a full standalone it can be done. This of course, only if you stay naturally aspirated, for forced induction you definitely need a full standalone ECU.

Benefits of ecu remap:

The main benefits of the Mazda v6 ecu remap are:

  • Run a 2.5 Engine on 1.8 ECU with the correct fuel and ignition timing.
  • Use any VAF (mass air flow sensor aka MAF) with any obd1 ECU.
  • Change the VRIS engagement and configuration (Variable Resonance Induction System) to increase low and midrange torque.
  • Change RPM Limiter.
  • Adjust fuelling and ignition timing to compensate for breathing mods and to increase power.

Which ECU are eligible for remapping?

Any obd1 ECU that stores the maps in the 27C256 Eprom is virtually chippable, the one that I know of are: KL31, KL01, K819, KL07, KF11, KL55, KL86. For these ECUS I can provide stock firmware to study purposes or to program it into any ECU.

Let’s begin: Chipping your ECU. *You need soldering skills*

With chipping i mean to replace your EPROM with a dip28 socket, on top of where you will put your EPROM (27C512 or 27C256 or EEPROM equivalent). Stock EPROM (27c256) doesn’t have a window to UV erase it, so we need to replace it with one that allows you to erase it with the aid of an UV EPROM ERASER.

First of all, remove the ECU from your car, mine was a OBD1 K819 ECU.

Open your ECU taking care to not break anything, an antistatic wrist strap would be good to wear to not damage any component with static electricity discharge.

Now locate your EPROM. You should be able to read “27c256” on the body of the integrated circuit.. These chip contains the firmware of the ECU. Now prepare yourself because you need to unsolder it and unsoldering it will require good skills and patience.

To correctly desolder it you need several tools:

  • Desoldering braid
  • Desoldering vacuum pump
  • Soldering flux

If you have never done soldering work on eletronic boards I suggest you to do some practice on other scrap boards before attempting to desolder one of these components, because these are really a pain to do. I could also recommend to go to a professional but.. That’s a good reason to learn soldering. Heheh 🙂

After your EPROM is desoldered, you need now to solder a DIP28 Socket in order to allow fast insert and removal of the custom EPROM.

Those sockets and erasable Eprom are easily available through internet, before attempting to chip your ecu, make sure you have like 3 or 4 of these, because you could damage these in the process, especially if you are a novice in soldering.

Be careful when removing the eprom from the socket and when placing the socket through the board holes as the pin can easily bend.

After the ecu is chipped (socketed eprom slot) you can either: buy an already tuned chip (I could provide some depending on the application), or develope your own map using a wideband air fuel and a knock sensing device or a dyno. In order to develope your own map you must understand EVERYTHING about the engine and combustion process. I will make some post explaining the basics but since you can make big damages if you make a mistake please avoid if you don’t feel confortable changing ECU parameters.

For this post is everything, the part 2 will explain what you need to program the EPROM and what you can really do by tuning the ECU firmware.

Thanks for reading. 🙂