Haltech F9A - Manual (Page 52)

51
Chapter 7
Cold Starting and Running
The Haltech F9 has features to modify fuel delivery to aid in starting and running a cold
engine. The Cold Start Prime map gives a cold engine an initial burst of fuel just as the engine
begins cranking. The Coolant Correction Map modifies the normal fuel injection until the
engine reaches normal operating temperatures.
7.1 Cold Cranking
At cold crank the air speed at the inlet manifold is very low. As a result a lot of fuel that
would normally travel in the air, sticks to the manifold walls and doesn't enter the engine. The
cylinder chamber temperatures are also low which leads to poor combustion. To overcome
these inefficiencies, it is necessary to prime the engine with a long pulse of the injectors at the
start of cranking to ensure that the engine has enough fuel in the cylinder to fire.
The F9 provides a cold start fuel prime that is adjustable at all engine temperatures. This
allows the duration of the prime pulse to be optimised for cold cranking under a wide variety
of conditions. Access the Cold Start Prime function from the Fuel Maps and Setup Menu.
The cold prime map specifies an injection time based on engine coolant temperature. The
height of the bars define the actual duration that the injectors are open. A typical map is
already loaded into your F9 and this should not need to be modified unless you are having
trouble cold starting the engine. Any changes like this should be done Online, so the change
can be reversed if the engine becomes harder to start.
Over priming the engine will cause it to flood and not start. To clear a flooded engine, open
the throttle fully and continuously crank the engine. Do not pump the throttle as this will only
worsen the problem.