Bogging or loss of power is either due to too much fuel, not enough fuel, or no
spark. Due to the varied amount of conditions that can triggers these
problems, it is very helpful to note under what exact conditions you're
experiencing this problem. Most times, the symptons are extremely
consistent and easily repeatable.
If you're using larger or upgrade fuel injectors, having too much fuel will
cause bogging problems. Unless this increase in fuel capacity can be
compensate for, just dropping in large fuel injectors will not automatically
mean the engine will perform well. In most cases, without a fuel
computer (i.e. A'PEXi S-AFC) or a stand-alone EMS ECU (i.e. Haltech) compensating
for the extra fuel capacity, the larger fuel injectors will cause bogging
problems due to too much fuel which causes an overly rich condition.
If you replace the secondary fuel injectors with large units, and you feel
the engine bog around the 4,000RPM or slightly under that RPM range, this is
a sure sign the larger fuel injectors are causing the engine to run too rich.
Sometimes, the stock ECU triggers a limp-home mode that causes the engine to
run very poorly. This is a last-resort safety feature that allows you
to limp the car home but keep engine damage to a minimum. On the Kouki
FC3S, a bad electronic oil metering pump can easily trigger an error code "20"
or "27", which will cause a limp-home mode that causes the engine to run
very badly over 2,000RPM. Please check error codes from the ECU
to eliminate any obvious problems that the stock ECU would sense.
FC3S Pro - How To's, Scanning ECU for error codes for Zenki FC3S
FC3S Pro - How To's, Scanning ECU for error codes for Kouki FC3S
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