Cost: $250

Difficulty:

Time: 30-40min

The engine management systems used by BMW are the key to maximum efficiency and minimum fuel consumption... What we want is more power so re-tuning the factory chip provides substantial performance gains and more aggressive set up while maintaining emission standards.

From what I have read and tested , the EAT Ultrachip and Jim Conforti chip are the best chips suited for the E34. But the Dinan Gen III works fine too (mostly high end power).

Only drawback: it is expensive (US$ 250) and you have to drive 92 octane gas. Only the EAT Ultrachip is affordable with it's 199US price.

Gain reported with Jim Conforti chip.

4) DME harness may now be removed from DME unit by lifting up

note - there is a set of tabs on the opposite end of the harness from the latch that are used to line up the harness contacts for installation - line this up first during reinstallation

5) Remove the DME mounting clips (pull upward) that secure DME to E-box chassis - DME will now be able to be slid/lifted out of the E-box

5b) On certain model (like the 535i) the DME is held by two screws.

6) DME Unit removed.  To remove the DME chassis cover, remove the (4) #20 Torx screws securing the DME cover to the DME chassis. Next you need to lift outward on the white pin on bottom of DME chassis to unlock the mounting pin in the center of upper DME board.
6b) On certain model (like the 535i) the DME cover is held by tabs that need to be pried out.

7) Lift upper DME board away from DME chassis
In the 540i, there are a few snapping mounts that will disengage during this part of the procedure. a- one center pin mount. b- two tabs on DME harness (note - these can be released with either a screwdriver or the like to lightly pry tabs inward). c-two outer mounts (picture in the right). The upper DME board is now free to slide out / away from the DME harness
7b) Nothing to do for the other model because there is only one board.

540i DME (two boards)

535i DME (one board)

8)  You may now lift / pivot the upper board away from the DME chassis to expose the chip location that will be involved with the chip swap.
8b) Nothing to lift on the other model.

14) Stock chip removal: the white or black stock chip cover will need to be removed first, this is done by inserting a narrow screwdriver into one of the pry slots on the chip cover and prying to release the cover from the chip (note - cover cannot be installed when performance chip utilizes a decryptor board)
Next - make note of the orientation of the stock chip in the socket, which end the notch in the chip is towards.  The new chip will need to be installed in this orientation.  To pry the chip out, insert a small narrow screwdriver under the stock chip at one end and pry up slightly - repeat on other end of chip and repeat back and forth until chip is unseated from the socket.  Do this in very small amounts of lift to ensure that chip is removed from socket without bending the pins.

Installation of the chip is quite easy.  Assure that the tab/notch on the chip you are installing is in at the same end as the stock chip was.  Gently press the chip into the socket - assure the the chip is fully seated into the socket.

15) On the 530i/540i, since the decryptor board was used in this application - the chip was too tall and the aluminum case needed to be lifted slightly away from the top DME board to prevent excessive rubbing between the TMS Conforti chip and another IC on the lower DME board
I chose to clip a washer in half and shim the case up a bit on the rear two DME cover chassis mounting points to give the upper DME board more room inside the case so that the chips (TMS Conforti chip on upper DME board and an IC on lower DME board) were not rubbing.  I secured the washer/shim with electrical tape.  These pictures were taken after two months of running with this setup and no excessive rubbing/wear was noticed on the conflicting chips (TMS Conforti chip on upper DME board and an IC on lower DME board).

If the car starts, everything is fine, if not... you may have a bent pin or the wrong chip and/or fried your computer... Arg!
You may want to call and double check that you have the right chip prior to change it (tell them the last 3 digits on the bosch sticker located on the computer 400, 401,402 or 403)