MAHLE RTI ELF-1 - Manual (Page 13)

Page 10
EVAPORATIVE EMISSIONS SYSTEMS
Basically there are two types of EVAP Systems. Vacuum operated and electronically operated. Both
types are designed to ensure that gasoline fumes from the fuel tank do not get into the atmosphere.
Earlier vacuum operated systems simply provide a vacuum signal from the engine, which opens a valve
(diaphragm) on the top of the canister that allows the stored (adsorbed) gasoline fumes to be sucked
into the engine once it is running.
Electronic systems use a computer controlled solenoid in place of the older vacuum control valve.
Additionally OBDII Systems utilize an in-tank vacuum/pressure sensor that is monitored by the on-board
computer, as well as additional venting solenoids. Most manufacturers recommend that any pressure
applied to the system be kept below 1 PSI. ELF-1 will accomplish this in the 1 PSI mode.
The quickest & simplest method, regardless of which type of system being testing,
is to fill the system through the EVAP port with the appropriate adapter. This will
allow fog to fill the entire system, without disturbing it, thus checking the gas cap
too. In some cases, opening the gas cap while filling the system with fog may be
advantageous, since this may help distribute fog more evenly throughout the
system.
A Custom brass EVAP port adapter is supplied.
ELF-1 provides sufficient volume to fill the entire system in just a few minutes.
An alternate option is to fill the tank via the fuel cap. It is recommended that a shop cloth be used as
a gasket, along with the appropriate supplied rubber adapter. The cloth will also protect against losing
the adapter in the tank.
Success in locating leaks with higher pressures can be realized by isolating or removing components
from the vehicle
and increasing the pressure. Such defects as faulty or failed seam welds in plastic
evap canister housings may be found in this manner.
HVAC CONTROLS
Vacuum controlled HVAC systems may leak. In many cases it’s even possible to hear the leak.
Pinpointing it under a crowded dashboard may be more difficult. Applying fog to the main vacuum
source will usually point out the leak.
HOSES & HEATER CORES
While in most cases a heater hose leak is obvious, many later vehicles have hoses and piping routed
in hard to see and reach locations. Tighter engine bays and newer configurations have forced the use
of metal tubing to replace the rubber type heater hose. Frequently, disconnecting just one end of a
heater hose (empty of coolant) and applying ELF-1 to it, will provide an answer to a leak location. If not,
by disconnecting both heater hoses at their source, then plugging one end, ELF-1 will fill the area and
will often reveal the leak.
Heater cores can be tested quite simply. Drain and disconnect the lower hose. Turn on the ignition and
the blower motor on low with defrost selected if possible. Apply ELF-1 to the heater hose while
observing the closest defroster duct. In some cases, it may be necessary to run the engine for this test.
If so, remove both heater hoses from the heater core and join them together (usually with a flushing
T). Plug one of the heater core pipes and apply fog to the other. Start the vehicle with the defroster and
low blower speed selected.
AIR CONDITIONING SYSTEMS
Not suitable for evaporator or refrigerant line porosity leaks.