Haltech E6X Manual DOS Version - Manual (Page 112)

E6X Manual
112
APPENDIX D FUEL SYSTEMS & STAGING
The best ECU installation will yield poor results if the fuel system does not meet the demands
of the engine. Insufficient fuel flow can lead to lean fuel mixtures and detonation that will
ultimately cause serious damage to the engine. For the safety of your engine, we urge you to
check your fuel system's capacity and ensure that there will be sufficient supply at all times. A
fuel pressure meter should be used during testing and tuning to ensure that fuel pressure does
not fall out of regulation i.e. that the pressure does not drop or oscillate.
This appendix offers guidelines to testing your fuel system and suggests some solutions if
there are supply problems. If you find you need to modify your fuel system and are unsure
what to do, contact a Haltech dealer for advice.
WARNING:
FUEL IS DANGEROUS. BEWARE OF FLAMES, CIGARETTES,
ELECTRICAL SPARKS, ETC.
D.1 Duty Cycles
Fuel delivery is obtained by pulsing the injectors synchronised with the engine speed,
allowing fuel to flow during the period that the injector is open. The time while open is called
the injector pulse width. As engine speed increases it is possible for pulse widths to overlap
so that the injectors are effectively switched completely on. This is referred to as 100% duty
cycle.
When 100% duty cycle is reached the fuel flow from the injectors has reached its maximum.
Increasing revs brings with it the danger of an engine lean out.
WARNING:
LEANING OUT AN ENGINE WILL CAUSE DAMAGE TO THE
ENGINE IN MOST CASES.
The tables and graph below show the point at which the injectors will reach 100% duty cycle.
It is not common for this to happen but the potential for damage under these circumstances is
strong so care should be taken to check this factor.
Maximum Injection Time (in milliseconds[ms]) =
(120,000 x IgnDivideBy)
(Rpm x No. Cylinders)
eg. Maximum injection time for a four cylinder, on ign/by 2 red-lining at 6000 RPM is
(120,000 x 2)/(6000 x 4) = 10,