The tachometer did a good job
Setting up the tachometer helped me to find the cause of unusual problems
and showed me the solutions. One thing that made me to worry before was the
over heat indicator turning on sometimes although the engine was still cold because
it was only a minute after the engine was started. At the same time, the indicator
that warns the malfunction of a power steering motor was also on too.
While above problems are going on, the tachometer shows the idling rpm a bit
lower than the normal about 50rpm. In addition to that, the light from the LED set
to the tachometer blinked a little bit although the speedometer's back lights by
regular bulbes were just a bit darker than the normal and not blinking.
With these situations, you can easily guess that the generator is not generating
enough voltage and there is a ripple at the 12V line. I decided to check the voltage
using my old oscilloscope.
Look at the spike. It is peaking 17.2V. ( 1 division H: 10msec, V: 1V ) The observation
was done at the 12V DC line to the ECU. From where does the spike come?
Those who are familiar sure can guess that those are ignition pulses. The direct
ignition system tends to have a problem like this due to the fact that the DC is
that will cause this type of spike or the ripple at the 12V DC line. In order to eliminate
spikes, I just added capacitors to every electrolytic capacitor in the ECU box
as a trial as were below.
For 12V lines, low ESR electrolytic capacitors were added and for the 5V line, OS
capacitors were added.
The result was as follow.
The spike is still bigger than the ripple from the generator but it is not as big as
before. In the photo, the explanation in Japanese says 10msec but it is 5 msec.
( H: 5msec/div, V: 0.5V/div)
With this condition, there are no more malfunctions on indicators. What I was
amazed was that the engine had more power than before. I especially notice
much bigger torque at the low rpm. I almost felt it runs like a new.
There also had a big improvement when driving with the air conditioner on. I should
have done this experiment earlier. I now can say the capacitors used by Honda for
the Life (LA-JB1) are not functioning well. I do not say it is a design fault but
designers have to select electrolytic capacitors for ECU carefully .
I just have checked how much current was going through the capacitor putting
a 100 mohm resister series at 12V DC line.
Although it is 100 mohm resister but it shows 33A of current going through it by the
calculation. You can see how much big energy is bypassed by the added capacitor
and it improves the engine power or should I write to recover it.
