I recently purchased performance chips for my 85 - anyone with experience installing them? Are they located in the fuse box or in the Bosch boxes against outside of passenger floor compartment?

Be careful when opening the modules and swapping the ROM chips. I suggest taking pictures before taking the modules apart so you can verify everything is properly installed and reassembled. Be aware that if you make a mistake and damage the printed circuit board, it can be VERY expensive. These suggestions are only that, no responsibility is assumed.

a. LH Box (25 pin 1984 (Euro) - 1986 LH modules)

1. There are a few tabs indented around the module that need to be bent up to expose the PCB. The PCB resides "upsidedown" so the EPROM cannot be accessed unless the PCB is removed. Screws need to be removed. Two plastic clips hold the PCB in place. They must be gently moved a bit to release enough tension for the board to be removed.

2. Put a small label with “LH” on the EPROM chip (so if you ever decide to return to using the stock EPROM, you know which goes where.) Keep the old EPROM, you never know if/when you'll want to go back to stock.

3. Note the “notch” in the EPROM chip shows the proper the orientation

4. It is best to purchase an “IC-Puller” to remove the EPROM. If you apply uneven pressure, you’ll bend the leads.

5. When you install the “tuned chip” double check the orientation. The socket has an indentation as well as the chip [Warning, I’ve seen sockets installed backwards and the orientation indicator was thus wrong, device orientation, not socket orientation is what counts].

6. Most Dual Inline Packaged devices (DIPs) have pins splayed a bit wider than the socket. Gently put the legs of one side of the DIP into the socket and push until the other side legs fit into the socket.

7. Plug the module in and MAKE SURE THE CAR STARTS before reattaching the lid. If the DIP is inserted backwards, or the wrong chip is inserted, the car will not start.

8. Reassemble the LH module.

a2 Instructions for S4 and newer (35 Pin LH)

1. Gently bend the lid tabs back, use a pair of pliers vs. a screwdriver (you may need to pry the tab up a little with a screwdriver).

2. Follow steps 2 - 7 for the 25 pin LH module.

3. Reattach the lid.

b. EZF Module [1984 (Euro) - 1986 25 pin 928s]

The EZF is a single board device. Just remove the lid (similar to 35 Pin LH instructions above). Follow the suggestions for removing the EPROM and replacing it.

c. EZK Module [35 pin 1987 and newer]

There are several screws to remove.

This is more difficult than the LH. The EZK has two PCBs connected by a ribbon cable. Inside the module are two strips of plastic insulation, be sure not to misplace the plastic when removing the PCBs.

You must be very careful when you split the two boards to gain access to the EPROM, the plastic pins can easily crack.

The comments about EPROM labeling (this time label EZK), EPROM orientation, and DIP installation and testing before complete assembly apply to the EZK module.