BMW E30 3 Series Performance Chip Installation
Jared Fenton

Difficulty Level: 3
Difficulty scale: Adding air to your tires is level one
Rebuilding a BMW Motor is level ten

     In this tech article, we will discuss installation of a performance chip in the E30 BMW.  While this tech article is specific to the E30 325is, the procedure is the same on nearly every BMW.

     Why change the chip? The simple answer is more power. I recently go a hold of a Dinan performance chip for my E30. The benefits of this chip include raising the factory rev-limiter to 6900 RPM and increases horsepower from 168 to 183. It does this by essentially re-configuring the fuel injection map to advance the timing, fuel pressure, etc. This translates into a dramatic seat of the pants change in power, or as we refer to it, the butt dyno.

Replacement is a generally easy procedure, and should not take more than two hours.

     The first step is to disconnect the battery on the car. Any time you are working around fuel injection components, you should disconnect the battery to prevent voltage spikes. This is important. If you fail to disconnect the battery, it could fry the computer.

     That said, lets begin. The first step is to open the glove box. With the glove box open, look up, you will see there is an access cover. Remove the screws holding it in place, and remove the cover plate. You now should be able to see the computer. The computer is held in place by four 10mm bolts as shown in the picture. Remove these nuts. The computer should now drop down and will be still connected to the harness.

     You will see that the harness is held to the computer by means of a large metal clip. Simply pull back on this clip, and the harness connector will slide back and free itself from the computer. Now the computer will be free of the car.

     Now to remove the existing chip, you will first need to disassemble the computer. The first thing to do is ground yourself to the computer frame. The reason for this is to prevent static electricity from discharging and possibly damaging the computer. Any good computer store will carry anti-static straps that attach to your wrist, then clip onto the chassis. It’s a good idea to use these if you are working around high levels of static electricity.

     Next, look at the back of the computer. You will notice a series of tabs holding the cover in place. Pry these back very carefully, and you will be able to remove the cover. With the cover removed, you will now see two circuit boards stacked on top of each other. The chip is in between these two boards.

     In order to gain access, we will need to remove the upper board. To do this, look at the connector on the front. You will see the pins that plug into the wire harness. On the sides of the pins, you will notice two plastic tabs. In order to remove this circuit board, we will have to pull this board out. (pic OBC_connector_tabs)

     The first step is to go to the back of the board, where the cable connectors are. Very carefully pull the two boards apart at the back, they will separate. Now, go to the tabs at the front of the connector. Push them inwards, and at the same time, angle the board up. What this will do is lock the tabs inward, and help you remove the board. You may have to use a certain amount of force to get it out, but be very careful. If you feel anything hanging up, STOP, look around and see what the problem is. The board should now slide out of the connector. Once removed, carefully fold it over making sure not to damage the wires connecting to the lower board.

     Now, look for the chip that has a small plastic cover on it. This is what we are replacing.  Very carefully, remove the cover around the chip. A small screwdriver on either side should pry it off.  With the cover removed, very carefully place a small screwdriver under the chip, then using equal pressure on both sides, lift the old chip out of it’s receptacle.

     Now look at the new chip. Note the small indentation on one side, it is important that the new chip is oriented so that the indentation lines up with the receptacle on the board. Once you have the orientation correct, using light pressure, very carefully push the new chip into the receptacle. Make sure that you do not bend or break any of the pins while doing this.

     With the new chip installed, place the protective cover over it and lightly clip it in place. Next, re-orient the board so that the connector pins slide back into place as seen in the photo. Once in place, push the two boards together at the back , the two plastic connectors will clip together. Now place the protective cover back on the computer, and bend the holding tabs back in place.

     Now, take the computer back out to the car and re-connect it to the wire harness. It will slide in at an angle. Make sure to line up the guide pins correctly. When they are lined up correctly, moving the metal clip on top of the connector will move the connector back into place and lock it shut.

     Now, re-mount the computer to the underside of the dash using the four 10mm bolts as described before. Once in place, re-install the access cover between the glove box and the dash. Now re-connect the battery.

     Before we actually start the car and take it out for a test, it’s important that you make sure that you have 91 octane or better fuel in the tank. Keep in mind that installation of an aftermarket chip requires you to run high-octane for as long as the chip is installed. The reason for this is that one of the chip’s functions is to electronically advance the timing. If you advance the timing on any car without running a higher-octane fuel, it will cause detonation (commonly referred to as pinging or knocking) this can cause major damage to the pistons over time. So just remember to always use 91 or better from now on.

     That said, fill the tank with high-octane and start the car and take it out for a spin. In my car, I noticed a huge difference in the mid-range response and the overall performance of the car. It feels more powerful in the higher RPM range, however the low-end feels pretty much the same.

     Well, there you have it - it's really not too difficult at all.  If you would like to see more technical articles like this one, please continue to support Pelican Parts with all your parts needs.  If you like what you see here, then please visit our online BMW catalog and help support the collection and creating of new and informative technical articles like this one.  Your continued support directly affects the expansion and existence of this site and technical articles like this one.  As always, if you have any questions or comments about this helpful article, please drop us a line.