Spray Effect On Emissions; Cold Driveability And Startability; Table 8-1 - Injector Tip Soak Temperature Vs Required Fuel Pressure - Delphi Multec 3.5 Applications Manual

Multec 3.5 Fuel Injector Application Manual
Maximum Injector Soak Temperature
T less than or equal to 95°C
T less than or equal to 105°C
T less than or equal to 115° C
T less than or equal to 120°C
T greater than 120°C

Table 8-1 - Injector tip soak temperature vs required fuel pressure

8.4.2

Spray Effect on Emissions

8.4.3

Cold Driveability and Startability

Delphi Energy and Chassis Systems
Table 8-1 is intended as a guideline only. Vehicle hot fuel validation
testing is required to confirm adequate hot restart performance in the
specific application.
There are two primary areas to investigate with injector spray:
• Determine optimum spray targeting and atomization for a given
application
• Once optimum spray is determined, evaluate effect of production
variation on engine and vehicle performance
Injector spray includes spray targeting, spray pattern and droplet size,
which are a function of the director plate design and fuel system pressure.
(Reference section 3.8)
Emission effects would be tested on both a dynamometer and the vehicle,
while driveability effects would be tested on the vehicle.
Direct observation of injector fuel delivery on a running engine is possible
with a boroscope and high speed imaging through the intake manifold.
The interaction of the injector spray and the port geometry can be studied
to ensure that the fuel is being delivered as expected and not collecting on
port surfaces or the injector tip.
The purpose of cold driveability and startability testing is to determine the
effects of extreme low ambient conditions on vehicle driveability and
startability. Tests typically consist of a prep of the vehicle to stabilize
temperatures followed by a 6 to 8 hour soak. After the soak the vehicle is
started and driven away, and the performance compared to baseline
results. Temperatures for testing are typically less than -20
the test should be done using high RVP fuel in the 12 to 15 PSI (83 – 103
Testing Recommendations and Precautions
Recommended Fuel System Set Pressure
300 kPa
350 kPa
400 kPa
450 kPa
Contact Delphi
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F (-29 C), and
Revision: 11/05-1 8-3