How to Ensure Good Performance for Petrol Cars Converted by Gas Mixer Systems

How to Ensure Good Performance for Petrol Cars Converted by Gas Mixer Systems
After the cars converted to (LPG/CNG) gas from petrol, there may come up with problems like oil and gas co-firing, loss in power, performance declining in acceleration, gas over-consuming, malfunction indicator light shown easily, backfire or blasting. Correctly installing/turning ignition timing advance processor and Emulator, choosing appropriate spark plugs, adjusting power valves and idle valve on regulator/reducer, will effectively overcome these problems. These operations are important to ensure a good performance after cars converted by gas mixer system.
1. It is strongly recommended to use to a timing advance processor
1.1 The importance of using a timing advance processor
Take CNG fuel for example, this device change the car’s original ignition advance angle, and remain timing signal of original ignition for using gasoline. CNG octane number and fuel properties are all superior to gasoline, to advance ignition timing, will greatly improve engine performance:

1.11 Better dynamic property in acceleration.
1.12 Reduce energy consuming, fuel economy
1.13 Prevent backfire
1.14 When switching to gasoline, no adjustment is required.

1.2 Installation Precaution
1) Make sure design of the ignition advancer’s wiring harness is consistent with the car model.
2) Positioned away from water, moisture and high temperature
3) Keep away from ignition high-tension cable and maintain well insulated

1.3 Wiring Guide
1) Grey cable:
(Cut the signal cable of Crank shaft position sensor) to original car ECU;
2) Brown cable: (Cut the signal cable of Crank shaft position sensor) to signal cable
3) Red cable: 12V, to positive ignition coil
4) Black cable: To ground
5) Blue cable: To gas output of changeover switch (blue cable)
6) Yellow cable: Hooked to throttle position sensor (do not cut the wire)
Cables and colors from different supplier may be different, but wiring principle is the same.
1.4. Switch Setup
There is a 3-ways switch in red color, on the timing processor. Every way, if pointing to the direction of arrow= the switch is ”on”, or =”off”.
1.41 Advance angle setup: Control by switch 1 and 2, details as below chart. 

Advance Angle
Switch 1
Switch 2

1.42 Car types setup: Control by Switch 3.

Car type
Switch 3
All else types

1.5 Turning Notes:
1)Turn the adjustable potentiometer (of Throttle valve or throttle position sensor) clockwise to the end, red light is on, it means the timing advance processor connected yet
2)Turn the adjustable potentiometer anti-clockwise, until red light is off, do not change the timing advance angle
3) When well turned, red light will be on during acceleration, and off during deceleration.
1.6 Identify signal cable of throttle position sensor:
Throttle position sensor place near the throttle body, there are three lines. Measured with a multimeter under AC voltage, red pin connect to one of the three lines, black pin connect to Ground, when idling the voltage should be 0.5v or so; with engine speed increasing, the voltage should raise along with. Otherwise, signal cable should be one of the other two lines, indentify like this until you find the right signal cable and connect it with yellow cable.
Firstly, the timing advance processor must match with the car type; Secondly, wiring and advance angle are all very important, 12° or 15°? Please find out which is better.
2. Emulator is indispensable
2.1 Problems if no emulator
When converting gas on the conventional carburetor cars, usually use gas switch, to shut off the oil pump cable when running on gas, to stop the pumping of oil, preventing oil & gas co-firing. However the cars now are mostly controlled by microcomputer(ECU)--EFI cars, when converted to gas, on the one hand, in order to prevent the petrol nozzles from being blocked because of nonuse in a long time, it is required to start the car by petrol then switch to run on gas, so very time after the oil pump startup, there left nearly 2L gasoline in the piping between the oil pump and oil injectors, which will be under combustion with the gas, so this way did not completely eliminate the problem of oil & gas co-firing, the more time of startup every day, the more gasoline is consumed, this is the root causes of oil disappearing inexplicably when the EFI cars converted to gas. In addition, the oil nozzles are still open no matter it is running on gas or oil, this is not conducive to extending oil nozzles’ usage life. So after EFI car converted to gas, the system should be able to shut off the pump circuit and the fuel injector electrical circuit at same time, but should not shut off simply, otherwise the original car computer can not detect the existence of the injector signal, and enter into fault mode. This requires that when shutting off the fuel injector circuit, should also sends to the OEM ECU a virtual signal of oil injector circuit is still working. On the other hand, the signal detected and transmitted to OEM ECU by the original car oxygen sensor is different from that under running oil, the original car's ECU will memorize this and identify it as a fault and make record, when switch to run on petrol, this will cause problems like:
Idling is not stable, fuel supply is not smooth, power loss in acceleration, engine sputter etc.
Which cause high oil consuming or even unable to work on petrol. The existence of such defects make car users miserable, some users even disassembly the gas kits, quit using gas, resulting in a big waste of investment on the gas conversion.

2.2 Function of signal simulation controller (Emulator)
To not affect the petrol system, bi-fuel vehicles should use a signal simulation controller to solve the problem with its interference on petrol system. The role of signal simulation controller is: When using LPG/CNG, the Emulator shut off the petrol injector, stop petrol supply, meanwhile it provides injector simulated signals and oxygen sensor simulated signals to OEM ECU, to facilitate it works as it do under using petrol. It can take into account using petrol and using gas both conditions to ensure the bi-fuel vehicles work normally on two conditions.
2.3 Installation and turning
2.31 Installation Precaution
3.11 Make sure design of the ignition advancer’s wiring harness is consistent with the car model.
3.12 Positioned away from water, moisture and high temperature
3.13 Keep away from ignition high-tension cable and maintain well insulated
2.32 Wiring
The cables of emulator, is composed of 3 set wire bundles: Injectors cable (with plug/socket); Oxygen sensor cable (white and yellow); Power cable (blue and black).
2.321 Take off the original car injectors cable, insert into corresponding plug in connectors from emulator. Another plug in connector from emulator is to connect petrol injector. If emulator connectors do not match with petrol injectors, please cut them to connect.
2.322 Oxygen sensor cable (white and yellow): Cut off the oxygen sensor signal wire, signal output port connect to white from emulator, the other end to original car ECU, is to connect yellow from emulator. Note: for convenience of exchanging oxygen sensor in case, it is recommended cutting the wire after oxygen sensor plug.
2.323 Power cable (blue and black): Blue to the gas signal output wire (blue) from change over switch; Black to battery negative pole. 
Cables and colors from different supplier may be different, but wiring principle is the same.
2.33 Switch Setup
There may be a 2 micro switch in the emulator, turn 1 ”on”, 2 ”off”—do not mistake, or it will not work, check engine light will be on still.
2.34 Identify signal cable of Oxygen sensor
Find the oxygen sensor, generally there are four wires, only one is the signal wire connected to OEM ECU. Measured with a multimeter under DC voltage with range of 2.5V, red pin connect to one of the 4 wires, black pin connect to Ground. When running on petrol, oxygen sensor should output a voltage of 0-1V to OEM ECU about 7times every 10seconds. Otherwise, signal cable should be one of the other 3 wires, indentify like this until you find the right signal cable.
2.35 Precautions of measuring the Oxygen sensor
Measurement of the oxygen sensor is to use high resistance voltmeter, to prevent damage to the oxygen sensor, and the voltmeter range is better to be DC 2V, use pointer-type one--easy to read.
2.36 Turning method for Emulator signal frequency
When running on gas, measured with a DC voltmeter, output voltage between (the emulator wire to the original car ECU) and ground, should fluctuate between 0.2-0.8V. Adjust the emulator potentiometer until the fluctuation frequency of emulated signal between 0.2-0.8V, is the same as it is under running petrol—that’s about 7times every 10seconds.
3. Necessary to use ignition advancer and emulator for sequential injection system?
The answers are not uniform, depended on: the newly installed gas ECU is integrated with ignition advance angle automatically adjusted function and oxygen sensor signal emulated function or not. The gas ECU functions vary with different manufacturers and different prices, some cheap and simple versions have only petrol pump shut-off and fuel nozzle injection simulated capabilities, there is no ignition advance angle self-adjustment and oxygen sensor signal simulated functions, if so the ignition advancer and emulator must be added, power will be better, gas consumption lower, strange phenomenon after converting to gas will be eliminated. How to judge if the gas ECU has these two functions? Before conversion see the installation instructions and wiring diagram of the gas computer, after conversion see the actual wiring, if the gas computer have connectors for the original car crankshaft position sensor and throttle body sensor, then the ECU has the timing advance angle adjustment function, or there is no. If the gas ECU has two wires for connecting to OEM ECU and oxygen sensor, that means it has oxygen sensor signal simulated function, or there is no. But please note, some gas ECU, also has wire connected to oxygen sensor, but only one wire –this is for the original car oxygen sensor to detect the situation of gas exhaust, then send signal to the gas ECU in order to control the gas injection volume, it is not for sending the oxygen sensor simulation signal, the most distinctive characteristics of the gas ECU with oxygen sensor signal emulated function is: there is two wires connected to oxygen sensor rather than only one, it is necessary to add an emulator if the gas ECU does not have oxygen sensor signal simulated function.
4. Replaced with "special spark plugs for gas"
As the natural gas has higher octane number, combustion speed slower than gasoline, is required to have higher ignition energy, common automotive spark plug can not meet the requirements, after testing a variety of spark plugs it shows that, the Xiang Torch 3poles "natural gas spark plug (model 5407) " can satisfy this requirement, market price of this spark plug is within 3USD/pcs, it work well for both gas and petrol.
5. Solutions to problem of engine die off when idling or stepping on the clutch during running on gas at High speed

The reason of stalling: At high speed air feed too much, resulting in the engine cylinder’s air-fuel ratio is too lean. For sequential injection system, calibrate the gas ECU, increase gas injection volume of enlarge the gas injector nozzle sizes. For self-suction system (mixer system), adjust the idle valve on pressure reducer to increase gas supply volume to engine. The easiest method is to use tape to seal on part of the air intake manifold port, so as to reduce air feed rate at high speed, indirectly increase density of the gas mixture in engine cylinder, this method have no problem when running on gas, however when running on petrol, due to the air inlet port is reduced, the air feed rate decrease resulting in high density of oil mixture and high fuel consumption, so few converted petrol vehicles use this method, for those cars switching frequently between petrol and gas (for example usually run long distance on petrol), should use other methods as far as possible.
6. Power valve adjustment
The power valve is connected to the intake manifold. Run the engine for 10minutes when water temperature rises to middle level, increase the engine speed to 3000RPM. First turn clockwise until engine speed decline then turn counter-clockwise until engine speed raise, locate the position where engine speed rise or decline, finally turn counterclockwise 90° ~ 180° -- finished!
7. Idle valve adjustment, oil to gas
Idle valve is a bolt on the pressure reducer/regulator. Manage to keep the engine speed at about 1000RPM, adjust the idle speed screw, first turn it clockwise, then counterclockwise, locate at the position where reach the highest engine speed.
8. The gas converted cars’ performance good or bad depended on three aspects

After converted to gas quite a few people reflect such or those problems, in fact, the effect good or bad, involves with mainly three aspects: First, must install an right ignition angle advancer and emulator, and ensure correct wiring and turning; Secondly, idle valve and power valve must be turned and adjusted properly; Third, replace with "special spark plugs for gas". As long as the above three aspects done well, the effect of gas converted cars’ performance should be very good, one car user who use LGC’s conversion kits, with his car converted following these instructions, have run his car nearly 70 thousand KM, powerful almost same as running on petrol as far as now.
This passage is original from HongKong LGC Gas Equipment Co., Ltd (, if forwarded it please state this! (copyright)


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