The G1 is an adapter that allows a chip or emulator to be plugged into OBD1 memcal based GM PCMs.
The GP1 kit is a G1 chip adapter and two 27SF512 flash chips packaged together at a lower price.
The G1 is compatible with the following vehicles:
- 1986-1993 TPI & LT1
- 94-95 TBI trucks
The G1 is compatible with the following chips:
- SST 27SF512
- 27C128/256/512 based eeproms
Our revolutionary G1 adapter allows you to customize your ecu or pcm by bypassing your factory tuning, allowing you to insert your own custom programmed chip without the hassle of tearing apart your stock memcal. This can be useful if you plan on returning your car back to stock, or need to use your stock memcal as a template for a newly modified ecu.
(much of the content on the rest of this page is edited from Allan Reinke’s review on www.iroczone.com – thankyou very much)
So what exactly does this adapter do? In case you don’t know, GM ECMs (1986 to 1993 TPI and some 94-95 TBI stuff) utilize a memory calibration “memcal” unit. This unit consists of the PROM (calibration code) and resistor packs (for limp mode, cold starts, etc.). The resistor packs consist of two chips. One a 16-pin and the other a 14-pin. These are custom laser etched type resistor packs making them extremely difficult to duplicate. In other words, you need these resistor packs, you cannot copy them (as of right now anyway) and your car will have a hard time starting without them. Some Memcals have a more compex ‘non-EPROM’ half which contains knock circuitry, and the original (or one very similar) Memcal needs to be used in conjunction with the adapter.
What the adapter does is allow you to plug in your resistor packs so your ECM will still use them, and at the same time, “bypass” your existing PROM chip so you can install your own. By doing so, you can reprogram your ECM with no modifications to your factory memcal AND no soldering is required! The process of reprogramming your ECM is greatly simplified. You no longer need to worry about destroying increasingly hard to find memcals with a bad soldering job when you use a G1 adapter!
First things first. You need to access your ECM. This is easily done as it is located behind the dashboard, on the passenger’s side of the car. (In some other applications, it is located under the passenger’s seat area, in behind the dash, by the kickpanel, or under the hood usually up by the firewall.) If you look underneath the dash on the passenger’s side, you will see a wiring harness plugged into a silver box. This box is held in by two hex screws. First, carefully unplug the two connectors to the ECM (otherwise, you won’t be able to gain full access to the ECM as the wires will keep you from pulling the ECM all of the way out.) Each connector has a “latch” where you just push in the latch and wiggle out each connector. Take your time, they don’t just fall out.
Next, get a hex screwdriver or other means of removing the two screws holding the ECM in place. Once these are removed, the ECM falls right out (be certain to catch it!).
Now, with the ECM removed, you will need to use the screwdriver to remove the two screws holding the access plate on. Most of the time, the access plate will be stuck on the ECM. Use a small screwdriver and carefully pry around the access panel until it pops off.
Once the access panel is off, there sits your memcal. If your Memcal looks like this, then the G1 adapter should work for you. If not, then look at some of the other adapters such as the G2 and see if that matches up. Using your fingers, press the latches on both sides, away from the memcal. Doing this will “pop” the memcal up.
Once the latches are fully out, the memcal should come right out.
The memcal will not usualy fit in the ECM (with the adapter) with it’s cover on. On some applications it will, such as some of the 1227730 and 1227749 units. So we will most likely need to remove the blue cover on the memcal so that it will fit back in there. Very CAREFULLY, remove the cover with a small screwdriver, prying the clips. Again, be careful, clips will break off.
You only need to do the one side just enough to pop the side up and the other side will come right off.
In this example, we are using a EPROM chip installed directly into the G1 chip adapter. This is a good “final” install after you have a program that you know works the way you want but it is not very easy to change the program in the chip. The advantage of this is that you are much more likely to be able to put the cover back on the ECM with just a chip installed. (i.e. no ZIF socket or emulator cable) Install the chip with the U indention out. (Pin 1 faces left as in the picture) . If you are using a Flash chip such as the 29C256, then the chip will also have an arrow by Pin-1. This should also go out toward the edge of the adapter. Be sure to line up all of the pins on the chip and gently press it into the socket. Once you are comfortable with the feel, you will need to exert a little force to fully insert the chip. This can be tricky. Bent and broken pins can result if you are not 100% certain that all of the pins of the chip are lined up correctly.
However if you are just getting started tuning your car, you may want to use a ZIF socket (available from Moates.net for a small fee) or install the emulation cable from an Ostrich 2.0 or APU1 instead. You probably won’t be able to close the lid on your ECM, but it will be a lot easier for you to make changes to the program in the ECM.
After you have either a chip or emulation cable insterted in the G1 adapter, install your memcal onto the adapter. Simply line up the right side of the memcal to the right side of the pins on the adapter.
Press firmly and it should easily slide into place! In terms of original Memcal orientation on the adapter, make sure that the original ‘EPROM’ half is hanging off and that the ‘limp-home’ half is in contact with the angle header on the edge of the adapter. It should look something like this:
Next, the G1 and memcal combination needs to be re-inserted into the ECM. Place the adapter, memcal first, face down in the access panel. Then curve the adapter, memcal first toward the empty space in the ECM (bottom, but in the picture it’s up as the ECM is facing upside-down).
Once the adapter is in place, line up each side to each latch. See the pictures. Make sure it’s lined up before pushing down! You don’t want any bent pins in your ECM!
You have to ensure that the adapter is placed correctly in the ECM socket so that when you unlatch it, it’ll pop right up. It needs to be perfectly centered or you can bend pins in the ECM – not good. Once you are comfortable with the placement, press down on the adapter in the center of the two latches until the outer latches “click” and are in the “installed” position (up.) Give yourself a pat on the back – you’ve completed the physical installation of the G1 chip adapter!
Reinstall the access panel (only if you are NOT installing the ZIF socket or if you are using a low-profile ZIF like the S4!!!) and reinstall the ECM in the car by following the steps you took to remove it in reverse. If you are using the ZIF socket for testing purposes, you’ll be happy to know that the access panel faces towards the front of the car, away from the dashboard. It may be a little neck tiring, but you will be able to replace chips while the ECM is installed.