2008 RENAULT SCENIC fuel pressure

17C-8
MR-372-J84-17C000$059.mif
V2
GAS INJECTION
Fault finding - Introduction
LPG 3000
Program No: AB
Vdiag No: 08/10
17C
ROAD TEST (in Petrol mode, then in LPG mode)
–check that the stabilisation time is normal,
–check that the engine does not stall under sudden braking and that it maintains a stable idle speed until the vehicle
comes to a stop,
–put the vehicle in 4th gear, at a steady speed of 36 mph (60 km/h). Check that the vehicle accelerates
progressively under full load acceleration.
Maintenance operations:
–no adjustment,
–removal of internal components is not permitted,
–if LPG clips are removed, they must be replaced,
–if LPG unions are removed, they must be replaced.
The tank must be bled before removing:
●the fuel tank,
●a component bolted to the fuel tank,
To remove the following, bleed all gas contained in the gas circuit (except the gas in the tank):
●the filler neck,
●the pipes,
●the filter,
●the pressure relief valve,
●the solenoid valve. IMPORTANT
Before performing any work on the vehicle, drain the LPG circuit.
Only personnel who have undergone special LPG training can work with gas unions where gas is circulating and
which run from the expansion valve via the fuel tank.
Equally, only these persons are permitted to perform servicing and repair operations on LPG vehicles.
Workshops can only carry out work on the fuel tank if they have a degassing burner. If the tank cannot be
degassed, do not carry out any work and contact the Comité Français du Butane et du Propane (French
Butane and Propane Commission) by fax on 01 41 97 02 89.

17C-9
MR-372-J84-17C000$118.mif
V2
17C
GAS INJECTION
Fault finding - System operation
1. System operation:
Composition
–The LPG injection system consists of the:
–LPG tank,
–fuel sender,
–overpressure unit (thermally triggered),
–LPG solenoid valve relay,
–tank solenoid valve,
–reducer (LPG) or expansion valve (CNG),
–expansion valve,
–filling spigot or socket,
–LPG hose,
–tank pressure sensor,
–LPG pipes,
–unions,
–airtight cover,
–regulator valve or anti-return valve,
–excess pressure valve,
–LPG filter,
–temperature and pressure sensor,
–LPG computer,
–LPG expansion solenoid valve,
–gas injectors,
–LPG or petrol selection switch,
–fuel sender relay,
–LPG tank relay,
–fuel pump cut-off relay.
Operating principle
The GAS 3000 computer electronically manages the operation of the LPG systems (Liquefied Petroleum Gas) and
CNG (Compressed Natural Gas).
The engine must be started in Petrol mode. The vehicle will automatically switch to "Gas" mode after starting if the
"gas" configuration was selected beforehand. "Petrol" mode switches to "gas" mode after a certain time delay, which
depends on the engine coolant temperature.
Petrol mode operates autonomously. Information is shared between the Petrol computer and the LPG computer via
a CAN connection.
The K line shared by the two computers allows diagnostics to be run on both the petrol and the LPG systems.
The Petrol computer is also the supervisor of the LPG system and includes, in addition to petrol-specific functions,
functions for adapting engine management programming to LPG operation.
Therefore, the Petrol computer includes settings and variables that are specific for LPG operation, e.g. ignition
advance adjustment in LPG mode, LPG flow rate setting, richness regulation, engine operating mode, etc.
It controls the choice of program (petrol start-up etc.) and controls the transition phases for switching from one
operating mode to the other: Petrol → Gas or Gas → Petrol. The fuel pump is regularly supplied to keep the system
under pressure in the event of a possible return to "Petrol" mode (if the "Gas" tank is detected as empty or if a fault
is detected).
LPG 3000
Program No: AB
Vdiag No: 08/10
MR-372-J84-17C000$118.mif

17C-10
MR-372-J84-17C000$118.mif
V2
GAS INJECTION
Fault finding - System operation
LPG 3000
Program No: AB
Vdiag No: 08/10
17C
The GAS 3000 computer manages "gas" actuator control, i.e. the "gas" injectors, the gas system relays and solenoid
valves, the fuel pump cut-off relay and the management of the fuel sender. Before switching to "Gas" mode, the
computer always checks that the pressure and the temperature of the gas are correct and that the "gas" solenoid
valves are open.
The combustible material is stored in an independent toric tank. LPG is stored in a semi-gaseous state at a pressure
of approximately 15 bar.
CNG is stored in a cylindrical tank in a gaseous state at a pressure of approximately 200 bar, and is transported to
the expansion valve/reducer via a rigid high pressure pipe. The rest of the system is a low pressure pipe going from
the expansion valve/reducer to the injectors. For CNG, there is a gas filter between the expansion valve and the rail.
Malfunctions / Special cases
These are characterised by operation in Petrol mode, although the driver has selected LPG mode.
An operational fault must be caused by the LPG system if it cannot be reproduced in Petrol mode.
Forced Petrol mode when LPG is faulty.
The level 1 warning light is controlled by the petrol injection computer; the gas warning light is controlled by the GAS
3000 computer.
The system automatically switches to "petrol" mode when the tank is empty or when the conditions allowing
operation in "gas" mode are not satisfied.

17C-11
MR-372-J84-17C000$118.mif
V2
GAS INJECTION
Fault finding - System operation
LPG 3000
Program No: AB
Vdiag No: 08/10
17C
Expansion valve (CNG):
–Purpose:
–It enables the pressure of the gas from the tank to be lowered to a value which is compatible with the injection
system (injectors and temperature pressure sensor downstream from the expansion valve).
–The gas pressure is approximately 3 bar at the expansion valve outlet.
–It regulates the pressure in the injector rail to the pressure in the manifold.
Reducer (LPG):
– Purpose:
–It has the same functions as the expansion valve. Furthermore, it ensures that the fuel switches from a liquid state
to a gaseous state (the gas pressure is approximately 2 bar at the reducer output).
–Operation:
The LPG expansion valve and the CNG reducer are essential components and are composed of:
●a stage for lowering the pressure from 25 bar maximum to a pressure in line with the manifold pressure,
P
output = Pmanifold + 0.85 bars (LPG)
Poutput = Pmanifold + 1.8 bars (CNG with 100 bar of pressure in the tank)
●a pressure regulator, comprised of a system of valves, springs and diaphragms,
●a cut-off solenoid valve,
●a water heating system.
–The expansion solenoid valve
This component controls only supply of gas to the expansion valve. Controlled by the computer, the solenoid valve
allows LPG into the two stages of the expansion valve, thus supplying the LPG injectors.
2. Intersystem connections:
Connections to the other computers:
–Petrol injection computer,
–protection and switching unit
–instrument panel.

17C-15
MR-372-J84-17C000$295.mif
V2
17C
GAS INJECTION
Fault finding - Fault summary table
Tool fault Associated DTC Description
DF0032617 Engine speed inconsistency
DF0071B47 Main relay circuit
DF0131B40 Tank solenoid valve circuit
DF0141B42 Gauge supply circuit
DF0161685 Impact detected
DF0171094 LPG leak detection downstream of expansion valve
DF0180512 + after ignition feed
DF0191B05 LPG pressure sensor circuit
DF0201B45 Fuel sender switching relay circuit
DF0211B46 LPG tank solenoid valve relay circuit
DF0221B60 Computer
DF0241B43 Fuel pump cut-off relay circuit
DF026C073 Multiplex network
DF0291B20 LPG tank sender signal voltage
DF0300657 LPG tank sender supply voltage
DF0311B61 LPG pressure downstream from expansion valve
DF061C100 Multiplex network
DF0740336 TDC signal circuit
DF0800560 Battery voltage
DF0811B32 Cylinder 2 injector circuit
DF0831B00 LPG pressure sensor circuit
DF0871B34 Cylinder 4 injector circuit
DF0881B33 Cylinder 3 injector circuit
DF0921B05 Expansion valve downstream LPG pressure sensor circuit
DF0951B10 LPG temperature sensor circuit
DF0960641 Sensor supply voltage
DF0981B31 Cylinder 1 injector circuit
DF0991B49 Instrument panel indicator circuit
DF1031B41 LPG expansion valve solenoid valve circuit
LPG 3000
Program No: AB
Vdiag No: 08/10
MR-372-J84-17C000$295.mif

17C-62
MR-372-J84-17C000$472.mif
V2
LPG 3000
Program No.
Vdiag No: 08/10GAS INJECTION
Fault finding - Conformity check17C
SUB-FUNCTION: OPERATION IN LPG MODE (CONTINUED 2)
NOTESOnly perform this conformity check after a complete check with the diagnostic tool.
The values indicated in this conformity check are given as examples.
Application condition: Engine stopped, ignition on and LPG mode selected.
Order FunctionParameter or Status
checked or ActionDisplay and notes Fault finding
8LPG flow rate
settingPR111:LPG flow rate
settingIndicates the LPG flow rate
setpoint in g/h.
PR111 = 0 g/h
NONE
9LPG injection
durationPR110:LPG injection
timingDisplays the injection duration
in ms.
PR110 = 0 ms
10
Tank senderPR013:LPG tank
sender supply
voltage4.8 V < PR008< 5.2 VIn the event of a fault,
apply the interpretation of
fault DF030 LPG tank
sender supply voltage.
11 PR009:LPG tank
sender signal
voltageIndicates the signal voltage
compared to the pressure in the
LPG tank.For Logan: In the event
of a fault, apply the
interpretation of fault
DF029 LPG tank sender
signal voltage.
For Mégane II: In the
event of a fault, apply the
interpretation of fault
DF029 LPG tank sender
signal voltage
and parameters
PR009 and PR116. 12 PR116:Sender
resistanceFor Logan: Ignore this
parameter.
For Mégane II:
Tank full:
20 Ω ± 2 Ω
Reserve tank:
290 Ω ± 2 Ω
Tank empty:
320 Ω ± 2 Ω
13LPG
temperaturePR113:LPG
TemperatureGives the LPG temperature
in °C.
- 40°C < PR113 < 120°CNONE
14 Fuel pump ET025:Fuel pumpACTIVEACTIVE when operating in
Petrol mode. If there is
inconsistency, carry out
a full fault finding
procedure on the petrol
injection system.
Deal with any other faults.