Timing - Ignition

M HILL EAXMJHI at ean2.mecheng.nottingham.ac.uk
Wed Sep 18 08:11:50 GMT 1996


> Since we now have computers, we should be able to
> monitor something other than self destruct imminent and
> tweak and peak the timing in conjunction with the fuel
> to get optimum power and economy.
> 
> I truly hope that there are some good ideas out there.

By monitoring the pressure in the combustion chamber you can judge 
how well the ignition system is working, the problem with this is the 
price of the probes and the charge amplifiers required.  Another 
method is the spark ionisation.  Add another spark around 15 degrees 
after TDC.  The cylinder pressure should be at a peak around here.  
Then measure how long it takes for the ionisation current to decay 
from the spark.  This will tell you how much burning mixture there is 
at the time.  This is currently what I am looking at.  Another one 
you could try is looking at crankshaft acceleration.  Again something 
I will look at in the near future.  By measuring the max and min 
speed of the crankshaft you can tell which cylinders are firing 
better than others and hopefully sort out the timing and fuelling for 
them.  There will be problems with noise from the drivetrain 
however.  So there are ways, it is just a case of time and money and 
having the right equipment to measure what is happening and see if it 
will be useful.

Martin



More information about the Diy_efi mailing list