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steve k.
steve k.

Diagnostic Tool for BMW model 2002 User Manual

Congratulations! You have purchased a unique electronic tool specifically designed for tuning of the BMW Model 2002 - by a 2002 enthusiast! This unit is100% hand built.

To use the tool - First make sure the car is in the NEUTRAL position (and/or Park for automatic cars). No key in the ignition, all accessories off (FAN OFF).

Locate the diagnostic port under the hood (Driver’s/Left side close to firewall). Simply plug the diagnostic tool into the port; the plug is polarized so you cannot connect it backwards. Once plugged in, you will see some entry text that confirms the tool is properly connected.

Youtube presentation:

To start the car: turn the red ignition switch up, the red LED must turn on, next press on the start button. Again, make sure the car is in NEAUTRAL.

While the car runs, you can navigate thru the display menu with the “select mode” button:

1-Tach mode (default power-up mode)

2-Voltage mode

3-Dwell angle mode (display shows dwell since it cannot show “w”)

4-Oxygen sensor mode (needs to be activated, see below)

Note: The start button can be used alone, without the ignition on, for when you would like to make the motor rotate in small increments to adjust the valves, etc... It is preferable to disconnect the coil if you want to do so.

Dwell angle is useful principally for original point and condenser system. Pertronix and Hotspark units throw their own dwell values.

Pertronix: tested on one car at 65 deg.

Hotspark: 20 deg.

Point and condenser: (factory suggested) 59 to 65 deg with 0.016” gap

User selectable features:

-Selectable Tach mode

-Selectable 02 sensor mode

To change the user selectable feature, you must open the unit and locate jumper J8 “opt” on the PCB, and temporarily short J8 with tweezers while the unit boots-up.



  1. Disconnect the unit from the car (if it was connected already!!)
  2. Open the unit (4x Philips screws)
  3. Using a pair of tweezers, short both pins of J8 (picture above)
  4. Connect the unit to the car while J8 is shorted
  5. The unit will display SET UP
  6. Remove the short on J8

The unit is now in set-up mode. Lower right dot on the display must be flashing during the process.

-To change the 02 sensor mode, press the “select mode” button.

The display will show the new setting:

Off=02 sensor mode deactivated (default)

nb=02 sensor mode activated, narrow band 0-1v

lb=02 sensor mode activated, wide band 0-5v

-To change tach mode, use again J8

Display will show the new tach setting:

4cyl=4 cylinder mode (default)

6cyl=6 cylinder mode

8cyl=8 cylinder mode

Once the change is made, simply disconnect the unit from the car, new setting is automatically saved already.

All units are shipped with an extra pin taped inside so you can wire on permanently a 02 sensor on the factory plug on the car.


The 02 sensor input is located in the center of the plug on the tool, position #5 on the factory 02 diagram. NOTE: early model 2002’s do not have the diagnostic plug.


Disclaimer: This unit is intended to be used on an unmolested, undamaged stock wiring harness. If you have ignition upgrades and extra ignition current consumption, the unit may not work as designed.

-turn all accessories off

-make sure the car is in neutral

Any accidents, mishaps and/or damage involved with this are the user’s responsibility. The supplier of this product accepts absolutely no responsibility for any such occurrences.

Technical data:

Voltmeter: manually calibrated within 10mv, readout 0-18v 12 bit a/d converter

Tachometer: 100% digital 0.5% error 200rpm min 5000 rpm max (4 cyl)

Dwell meter: 100% digital ±1 degree accuracy from 200 to 2000 rpm

02 Sensor:

Narrow band: 12 bit accuracy a/d converter 0-1v from non-linear 255 points table

Wide band: 12 bit accuracy a/d converter, 0-5v linear, 0v=10 afr, 5v=20 afr

Reverse polarity protected on all pins

100% designed from scratch for this purpose, by Patrick Allen, it is not an adaptation of another circuit or anything currently found on the market. I own 100% of this design, including the software.

User Feedback

Recommended Comments

I too am interested in owning on of these if you have gotten around to making the additional units mentioned above.  I bought a Bosch motorsport Lambda Sensor and wiring kit from Dave Redszus of Precision Auto Research (630-766-4402) when I had my Kugelfischer injection pump rebuilt.  He provided exact instructions for instillation and a curve mapping out mV versus Lambda  (excess air factor) and a PhD level explanation of how to interpret.  It would be great to have an additional plug with this information on the diagnostic tool.   I have more specifics if anyone needs them.




Asheville, NC

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