1986 951 Zeitronix Wideband Installation

Copyright © 2004, Tom M’Guinness

This document can be freely copied in its original

form, for non-commercial purposes only.

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These instructions are based on my own installation of the Zeitronix wideband in my 1986 944 turbo. I installed the wideband, Zt-2 and boost gauge, but not the exhaust gas temperature (EGT) sensor.


Install O2 Bung.   The first step is to get the O2 sensor bung installed. The wideband bung needs to be installed after the turbo and before the catalytic converter.  It also needs to be installed so the tip is pointing downward.  I opted to install it in my test pipe, where it tucks up nicely behind the starter. With the test pipe in the car, I took a magic marker and marked a big dot where the bung and O2 would fit well.  I then took the test pipe to my local Midas shop, and they welded the bung in for free in about 10 minutes.



This is how the bung looks installed in the test-pipe.






And here is the test-pipe and sensor installed in the car.


Install O2 Harness.  I pushed the O2 sensor (phone jack end) into a pre-existing hole in the bulkhead wall into the battery area.  Then I stuffed the wire into the passenger compartment through the firewall hole behind the battery.  It takes some work to get the cable out from behind the glove box, but if you work at it, you can get the cable to route out behind the glove box.


On the end of the harness with the big O2 harness connector, if you installed the bung where I did, you are best off routing the harness wire down the passenger side of the firewall above the bell housing.  Letting it dive down near the Co2 sample tube.  Remember that the O2 sensor itself has about 2 feet of heat-resistant cable, so the big connector only needs to drop down to about the top of the bell housing.  Route the wires away from the headers and exhaust pipes.


12-Wire Zt-2 Connector.   This connector looks like a pain to install, but there is actually not much involved.  There are really three sets of wires.  Two wires get spliced into the DME/KLR harnesses.  Three of the wires get connected to the boost sensor wires, which can be done on the bench.  Two of the wires get connected to power and ground.  The remaining wires are not used.  I found it helpful to get organized on the bench, by connecting the boost sensor wires to the 12 wire connector, and clipping off the wires not needed.  My harness looked like this before I got near the car.


Here is how I connected the wires from the 12-pin connector


Wire 1  (red): connects to DME pin 18 (red/yellow) or other switched 12 volt source
Wire 2 – not used
Wire 3 (green): connects to
DME pin 21 (green/black, RPM signal)
Wire 4 (orange): connects to boost sensor’s green wire
Wire 5 – not used
Wire 6 (yellow) connects to boost sensor’s red wire
Wire 7 (black) connects to
DME pin 5 (brown, ground)
Wire 8 (brown) connects to boost sensor’s black wire
Wire 9 – not used
Wire 10 (grey) connects to KLR pin 22 (white/green, TPS)

Wire 11 – not used
Wire 12 (blue) spare input I connected to MAF
DME pin 7



It’s not pretty in there, but once you are done, no one will ever know.


Before tapping any wires, be sure to disconnect the battery negative cable, and remove the harnesses from the DME and KLR boxes.  If you look closely at the inside of the harness connectors, you will see that the pin numbers are marked.  When you tap into the harness wires, it is a good idea to check to make sure you have the right pin.  For example, for the TPS, when you tap the white/green wire, make sure that there is a direct connection between the wire you tapped and pin 22 on KLR connector.  I opted to tap DME pin 7, the AFM signal (actually the ARC2 signal on my car) for the user-defined input line.  I use solder and electrical tape in lieu of those vampire tapping clips.  The clips seem to work, but I have had several experiences of intermittent connection problems, so I now always take the time to ensure the connections are solid.


Boost Sensor.  The small boost sensor needs to be close enough to the Zt-2 for its harness to reach.  I ended up putting a T in the line to my aftermarket boost gauge and tie-wrapped the sensor to the underside of my glove box.  I tucked the Zt-2 behind the carpet on the passenger side transmission tunnel, so the display and data-logging wires can run easily to the passenger seat (to connect the laptop) or to the center console (for the display).  I opted not to install the display permanently.  m


I had no problem using the Zeitronix software on my Windows XP laptop. The only glitch is that my laptop does not have a 9 pin serial port.  I solved that problem by buying a USB to 9-pin cable converter, available at most computer stores.