For $ome rea$on$ IDM information other than the resistor mod is pretty much non existent. Here we hope to change things. Everything that we learn about the IDM will be documented free for anyone to make use of. This project is open and you can do with it as you wish. Hopefully someone else is interested in the IDM and can make use of this project as foundation work and take it to the next step should we retire. If we can help in any way just ask. That means if you have a specific question about anything or would like to see something else documented all it takes is a simple email. One rule to remember at this point is that anything we may do that is IDM related will be available to the public for free.

Things to determine:

1.      Signal bit relationship with injectors. The CID SIG appears to operate on the rising edge in respect with Fuel Delivery Signal. Bit naming is probably strait forward. 1-2-7-3-4-5-6-8.

2.      SMPS operating mode (continuous or discontinuous). The power supply appears to be a boost supply, opposed to buck-boost. This is a single ended supply so push-pull operation is pretty much out of the question without major power supply redesign. We also need to study the injectors as an integral component in the power supply. The injector drivers are likely to use fast recovery diodes to clamp the inductive spike generated from the collapsing electromagnetic field present in the injector. If this is the case I am lead to believe that the efficiency of the power supply can be greatly increased by adding a fly-back stage into the power supply. Of course this is all speculation; many things need verified at this point.

3.      SMPS Oscillator type and operating mode, ( R/C or Crystal) , (Fundamental, nth order harmonic) tests show that the oscillator is likely to be of the R/C type and operating in fundamental mode at 42khz. The voltage control appears to be 2.50 – 2.55 with external bias to the high voltage stage. The chip, pulse width control and loop status are not known at this point.

4.      Amount of power actually transferred to injectors from high voltage power supply(efficiency). Tests show that the power supply produces 112v and roughly 68v potential was measured across the injectors. This implies an efficiency of 61%. The left-right feed signals may limit current. Note: This is half wave power factor until more information can be found regarding the SMPS operating mode. More testing needs done here.

5.      Microcontroller architecture. Motorola (now freescale) markings have been noted on the MCU. An educated guess suggests the commonly used 68HC line of automotive microcontrollers. Considering the age of the IDM the MCU is not likely to contain flash memory. It is more likely to be OTP EPROM or mask ROM. If we can determine the microcontroller we may be able to tickle the code out of it even if the firmware is protected by fuses. This is the single most important component in the IDM. If this challenge can be met the possibilities are virtually limitless.

At this point you may be asking if it is really worth the effort. I personally believe that it is, you see the little time that i put into this project will be saved time and time again by anyone who wishes to take things a little further. Though i do not even own a truck to exploit this information i am getting plenty of experience out of this project. I'm sure a lot of people are already happy with this project and the information that it is providing as i am sure a lot of people are likely to be agitated to some extent that this information is being offered to the public with no fee. Anyone may do as they wish with this information, if you can build a device and make some money more power to you. There is a good chance that this project will lead to the open design and group buy-in of modification hardware. Even so, the basic concept still exists, and that is that information like this should be freely available.

We enjoy to tinker just as much as the next guy, and for those of you who just so happen to be a DIY tinkerer. We present the IDM MOD project. Enjoy!