Hi Kevin, re: the wiring position for the Z22XE engine in your LPG wiring howto below?
 Does the violet Lambda 1 wire connect to the 
Black wire in pin 57? 
I'm a little unsure, as you state Pin 57/8 Black/Grey?
Pin 58 is Brown and the other end of the Black from Pin 57 meets with a Grey which comes from Pin 24? before running in their own insulation sheath? I'm sorry if I'm being a Numbty but being Left Handed, apparently my thought processes are different (that's my excuse anyway! 

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The following table indicates on which connector pins these signals can be found for each of the petrol engine options and the colour coding of both the vehicle wiring looms and the Stag LPG system looms:
Engine Type   Y26SE/Y32SE  X25XE/X30XE  Z22XE  X20XEV  
Signal Name  LPG Loom Colour      
Switched 12v  Red(thin)  X86 Pin47 Black  Pin27 Black  X84 Pin64 Black  Pin17 Black  
RPM  Brown  X86 Pin35 Green  Pin43 Green  X84 Pin62 Green  Pin20 Green  
Lambda Sensor 1  Violet  X85 Pin28 Blue  Pin28 Brown/Blue  
X83 Pin57/8 Black/Grey  Pin36 Yellow  
Lambda Sensor 2  Violet/Grey  X85 Pin44 Blue  Pin27 Brown/Blue  N/A  N/A  
On the Z22XE, Y26SE and Y32SE engines there are two connectors on the ECU and we indicate above which connector is applicable. On the Y32SE/Y26SE X86 is the connector where the loom emerges and heads through the bulkhead into the car interior. X85's loom runs across to the cable tray on the engine.
On the Z22XE, X84 heads to the bulkhead while X83 heads to the engine.
The permanent 12v feed (the thicker of the two red cables in the Stag loom, with an inline fuse holder near the end) can be taken directly from the battery positive terminal. Ensure all other electrical connections have been made before connecting this (or leave the fuse out until you are ready to test).
The ground connection for the LPG system emerges on a thick brown wire next to the permanent 12v feed. this can be connected to the battery negative terminal.