Accessing the EPROM on Guzzis equipped with the Weber-Marelli 16M ECU
(Sport 1100i, Daytona RS, Centauro)

The following procedure describes how to access EPROM on Guzzis equipped with the Weber-Marelli 16M ECU. Normally, there are only two occasions when you should have to open up the ECU:

- to replace the EPROM

- to adjust the idle mixture

Accessing the EPROM:

1. Switch off the bike. Wait 15 seconds for the ECU to power-off (you'll hear a faint 'click' when it does).

2. Remove the seat. The seat is attached with two socket-head screws, one on each side.

i. Wrap the shank of a (8 or 10mm, can't remember) T-handled hex wrench with a piece of clear tubing to protect the bodywork.

ii. Look through the holes in the sidepanel and find the socket-headed screw that holds the seat on. It's plated, and so should be easily visible against the frame.

iii. Insert the T-handled hex wrench into the hole in the sidepanel that lets you align the wrench with the screw. There's only one that works.

iv.back the screw out about 4-5 turns. You don't have to remove it all the way.

v. Repeat for the screw on other side.

vi. Lift off the seat. If it won't come off, back each screw out a little further and try again.

3. The ECU is the metal box directly beneath the seat.

i. Remove the large rubber access plug from the top of the ECU. If it's got an intact Guzzi-logoed sticker over it, the EPROM inside is almost certainly stock.

ii. The EPROM is socketed directly below the access hole. It may or may not still be secured with a plastic hold-down. If it is, use a screwdriver to pry off the hold-down. For safety's sake, you should use a plastic screwdriver available from electronics component stores. If you don't have one, use a normal screwdriver and don't let it touch anything on the ECU's PCB.

iii. You should be able to see the label on the chip now. The stock chip has a label with dot-matrix printing on it that says something like "MG 16M" followed by some kind of version number.

iii. I forget which was the latest version of Will's chip for the Daytona/Centauro, but I think it was labeled "DAYR4". Not sure though, best to check with him:

At the time of writing, his latest chip for the Sport 1100i is labeled "WPC12".

If the chip on your bike plugs into a small daughter board, and the daughterboard plugs into the EPROM socket, it's an FIM chip.

4. If you want to replace the EPROM, you'll need a chip puller, which you can get from an electronics supply store. Don't be tempted to try and use a screwdriver, and you'll never be able to do it with your fingers -- it's too tight.

i. Take a good look at the EPROM. It's got notch at one end (faces towards the right side of the bike). You'll have to replace it in the same position. Otherwise, the bike won't run.

ii. Position the chip puller's jaws under the EPROM. Make sure they're securely under the EPROM, and lever the chip puller back-and-forth while you pull up on the chip puller.

iii. To replace the EPROM, place it on top of the EPROM socket, with the notch at the correct end, and look at both sides of the EPROM's legs. Make sure they are lined up over the holes in the socket.

iv. Place two fingers on the EPROM, and push it down into the socket. Push down a little at a time, to make sure you're not bending any of its legs Press it down firmly. It'll be a snug fit. 

v. If you still have the plastic hold-down, replace that too. (As originally delivered, they also came with a blob of
silicone seal on the hold down to glue it to the EPROM).

5. If you want to adjust the idle trim, you use the dial on the small square potentiometer next to the EPROM socket. The dial has 270 degrees of movement. Don't force it beyond its normal travel.

i. Using a screw driver, turning the dial clockwise to lean the idle, counter-clockwise to richen it. If you have access to a CO meter, try for 5-7% CO. If you don't, adjust it for best and fastest idle with good throttle response.

6. When you're finished, reinstall the rubber access cover and  cover it with a couple of strips of duct tape to weatherproof it.

7. Replace the seat and re-tighten its securing screws. 

Chris Kelly
Monte Nido, CA