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devanZX3 02-19-2010 05:25 PM

AEM wideband to xcal3 question
Tom said to make a post on here. I need to know where to get the firewire cable or if its something i can get local. and how to wire it to the xcal3

1turbofocus 02-19-2010 05:34 PM

I would like to see a sticky done about the fire wire , how its hooked up and the setting to make the gauge match the log

I get 2 to 3 emails a week about this and a sticky would help


BC_ZX3 02-19-2010 11:52 PM

I just finished doing this and had the same questions. Hope this helps.

Purchase a firewire cable available at most computer stores. Both ends should be identical.

Cut off one end near the connector and strip away and expose the inner wires. There will be six.

Here's the part that gives the most difficulty. Each coloured wire corresponds to a small brass pin in the other connector end. We need to determine which pin position corresponds to each wire colour. There are a couple of different colour schemes used depending on who makes the cable.

Make yourself a diagram.

Strip each wire end and then get out the handy multimeter and map each pin to its colour like so.

The result is something like that shown below. We can pick either of the two colours - in this case, red or yellow - that correspond to the firewire pins the SCT scanner uses for analog inputs. Red is Channel 2; yellow is Channel 1. We only need a single channel.

I chose red which corresponds with analog input Channel 2. Trim the other wires.

Crimp a connector on it and tape it up. You can solder it if you want; just make sure it's secure.

Now connect it to your AEM gauge harness. Use the white wire (to which I've already crimped a female connector).

Connect the rest of your wiring as shown here to power the AFR gauge. The interior fusebox is your best 12V power source and the unpainted metal fusebox housing can act as your ground. Put proper connectors on the exposed wire ends. You probably want a fusible link on the 12V power source.

Fit the unmodified Firewire cable end of your butchered Firewire cable into SCT scanner (at the top), the large SCT scanner cable end into the OBD II port of the car and a USB cable from the SCT scanner to your notebook computer, if you're using one to datalog.

When preparing to data log, go to "Data Logging" then "Set Up" in the SCT scanner menu and configure scanner analog inputs, when prompted i.e. "Configure Analog Inputs? Y/N" will appear on the screen. Select Channel 2 (or 1 depending on the wire you chose) and specify "Wideband" and then "AEM" from the scrollable list presented. This will apply a formula to the raw voltage generated by the sensor located in the exhaust stream and convert it into a more recognizable AFR ratio - the same as the in dash gauge will display - in the resulting logs.

You can datalog to the scanner itself or to the notebook using the Livelink software package.

When you've finished with the SCT data logging, simply disconnect the white analog input wire and cap it. Tie it up near the OBDII port out of sight until it's needed. Store your Firewire cable in a safe place ready for future use.

This set up worked for me without problem. Let me know if I've made any errors and I'll fix 'em.

mikealicious 02-20-2010 12:19 AM

Awesome write up man! One question for ya. Since I'm lazy and usually would mess something like this up, when the time comes, would you make me one and send it to me? Haha (I'd obviously pay for the cable and your time)

badass3 02-20-2010 01:09 AM

sticky this so i can find it later lol

devanZX3 02-20-2010 05:42 AM

This has got to be the most informative and descriptive write up,on how to do something i have ever seen. Very,very helpful.

sleepyboy 02-20-2010 06:13 AM

This is nice. I'm going to do this tomorrow.

1turbofocus 02-20-2010 07:54 AM

The fire wire SCT sells is it a direct plug and play ?


BC_ZX3 02-20-2010 11:08 AM

Thanks guys. I'm glad you found it useful.


Originally Posted by 1turbofocus (Post 3162860)
The fire wire SCT sells is it a direct plug and play ?


I had a look on SCT's web site for an appropriate cable before doing this and most of the cables shown are for earlier flasher models and/or purposes. Also the prices and shipping wait times put me off. Link

Some other SCT vendors do sell a firewire cable and mention wideband data logging but they do state modification of the wire is required. This one even has a pinout diagram.

I had a spare firewire compter cable hanging around home so I didn't have to buy anything.

Juantron 02-20-2010 08:15 PM

What an awesome write-up man!!! I couldn't have said it better myself ;)

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