LPG Generations

LPG systems are generally designed to run on Petrol engines but have varying degrees of sophistication:

1st generation
Venturi, open loop systems (no lambda control) with no electronic controls. Generally only installed on simple carburettor engines. System fully adjustable by installer.

2nd generation
Single point, analogue lambda controlled systems used on 3-way catalytic vehicles. Adjustable at idle.

3rd generation
Single or multi-point injection, microprocessor controlled with closed loop, emission compliant systems. Have self-learning capability but not adjustable by installer. Basic on-board diagnostic fault code storage.

4th generation
Multi-point, sequential injection system, microprocessor
controlled closed loop emission compliant. Not adjustable.
Does not interfere with EOBD system

5th generation
Multi-point, sequential injection system, microprocessor controlled closed loop emission compliant. Not adjustable. Will integrate with vehicle EOBD systems.

Euro 3
the introduction of Euro3 engine regulations on 1st January 2001 required vehicle manufacturers to meet significantly higher emission and on-board diagnostic standards.

As a result of changes made to 2001 engine systems most of the 3rd Generation LPG systems cannot be installed. This is because the LPG software is specifically written for each engine and vehicle model and it takes several months to modify the programme.

Sequential SGi
A new generation of Sequential Gas Injection (SGI) systems is being developed to overcome this problem. SGI is a new concept that ‘reads’ the data sent to each petrol injector and uses this information to control the LPG injectors. Effectively the petrol engine management system is controlling the LPG via a computer interface that translates the raw data to compensate for the different characteristics between LPG and Petrol.

Although SGI systems still need to be tailored for each vehicle and engine the development time is considerably shorter and units are already available for some Renault, Peugeot and Citroen vehicles.

1. Microprocessor   
2. Fuel switch   
3. Fuel switch 
4. MAP sensor  
5. Vaporizer
6. Shutoff valve LPG
7. TPS sensor
8. Injector LPG
9. Lambda sensor
10.RPM sensor
11. LPG tank