Unofficial FAQ: Ignition corrections

http://www.tegger.com/hondafaq/igniter-operation/index.html

Hopefully this is correct now.

Thanks to all for their help, especially Jim Yanik.

 

TeGGeR® wrote:

http://www.tegger.com/hondafaq/igniter-operation/index.html

Hopefully this is correct now.

Thanks to all for their help, especially Jim Yanik.

--
TeGGeR®

The Unofficial Honda/Acura FAQ
www.tegger.com/hondafaq/
--------------------------------------
I think in the 1990 Honda Civic, the igniter also provides
for for some PWM control. It senses the back EMF and
kills the coil drive at the correct momment to insure a
hot spark. I played with an ignitor and couldn't get it
to because correctly until I connected to to a Honda
igntion coil. As I varied the frequency of the drive pulses,
all the same width, the output created wider pulse at higher
"RPM".

Terry

 

TeGGeR® wrote:

http://www.tegger.com/hondafaq/igniter-operation/index.html

Hopefully this is correct now.

Thanks to all for their help, especially Jim Yanik.

--
TeGGeR®

The Unofficial Honda/Acura FAQ
www.tegger.com/hondafaq/
--------------------------------------
I think in the 1990 Honda Civic, the igniter also provides
for for some PWM control. It senses the back EMF and
kills the coil drive at the correct momment to insure a
hot spark. I played with an ignitor and couldn't get it
to because correctly until I connected to to a Honda
igntion coil. As I varied the frequency of the drive pulses,
all the same width, the output created wider pulse at higher
"RPM".

Terry

 

interesting! i'd read that they did that, but just haven't had the time
to sit down & test for it. thanks for the confirmation!

 

interesting! i'd read that they did that, but just haven't had the time
to sit down & test for it. thanks for the confirmation!

 

"PWM" control?

Do you know the mechanism by which it sees the back EMF?

So how come my news server has this message, but not Terry's?

And yes, that's one of the very nice features about electronic ignition
versus Kettering. With Kettering, the very moments you need a fat spark are
the very moments you get a weaker and weaker spark since the system has no
way of increasing dwell time to compensate for RPM.

 

"PWM" control?

Do you know the mechanism by which it sees the back EMF?

So how come my news server has this message, but not Terry's?

And yes, that's one of the very nice features about electronic ignition
versus Kettering. With Kettering, the very moments you need a fat spark are
the very moments you get a weaker and weaker spark since the system has no
way of increasing dwell time to compensate for RPM.

 

as the magnetic field decays inducing a current into the secondary [high
voltage] coil, the same is going on with the primary coil, but smaller.
just need to measure it. presumably the chips we see in graham's
photos either have a map or even calculate "dwell" based on what they
measure. but i'm guessing, i don't know for sure.

ah! news servers! fickle things.

which is why people used to experiment with dual plugs and dual ignition
systems occasionally. total pains in the rear and highly unreliable,
but it was a stab in the right direction. but you're right, once
electronic ignition came in, and it wasn't unreliable or expensive,
suddenly, it was ok to go electronic with everything. and that's been a
good thing up until recently. i don't see current chip technology
physically having the longevity we've been so far used to. and of
course, with increasing reliance on mysterious black box electronic
componentry, how do you know whether a manufacturer caves in to the
temptation to program in an end of life? that already happens with ink
jet cartridges, regardless of their fill state.

 

as the magnetic field decays inducing a current into the secondary [high
voltage] coil, the same is going on with the primary coil, but smaller.
just need to measure it. presumably the chips we see in graham's
photos either have a map or even calculate "dwell" based on what they
measure. but i'm guessing, i don't know for sure.

ah! news servers! fickle things.

which is why people used to experiment with dual plugs and dual ignition
systems occasionally. total pains in the rear and highly unreliable,
but it was a stab in the right direction. but you're right, once
electronic ignition came in, and it wasn't unreliable or expensive,
suddenly, it was ok to go electronic with everything. and that's been a
good thing up until recently. i don't see current chip technology
physically having the longevity we've been so far used to. and of
course, with increasing reliance on mysterious black box electronic
componentry, how do you know whether a manufacturer caves in to the
temptation to program in an end of life? that already happens with ink
jet cartridges, regardless of their fill state.

 

Looks good!

"flyback" voltage;when the coil is charged,the magnetic field builds
up,then when the charging current is removed,the collapsing magnetic field
generates a voltage in the opposite direction of the charging current.

The flyback voltage IS the HV pulse that the spark plugs get.

The mag field is generated by the primary,12V side of the coil,but the
collapsing magnetic field induces the flyback pulse in both the primary and
secondary of the coil,that's how the HIGH voltage is generated;the
secondary has many more turns of a finer wire(finer to fit more turns in
the same space);more turns,the higher the voltage induced.In the automotive
ignition coil,the primary is connected to the secondary,and the HV current
also travels through the primary.

That is why there's a bypass diode,it shunts the flyback current around the
Darlington,to keep it from breaking it down from over-voltage.It's part of
the path for the flyback voltage.

 

Looks good!

"flyback" voltage;when the coil is charged,the magnetic field builds
up,then when the charging current is removed,the collapsing magnetic field
generates a voltage in the opposite direction of the charging current.

The flyback voltage IS the HV pulse that the spark plugs get.

The mag field is generated by the primary,12V side of the coil,but the
collapsing magnetic field induces the flyback pulse in both the primary and
secondary of the coil,that's how the HIGH voltage is generated;the
secondary has many more turns of a finer wire(finer to fit more turns in
the same space);more turns,the higher the voltage induced.In the automotive
ignition coil,the primary is connected to the secondary,and the HV current
also travels through the primary.

That is why there's a bypass diode,it shunts the flyback current around the
Darlington,to keep it from breaking it down from over-voltage.It's part of
the path for the flyback voltage.

 

That is probably what the IC in the igniter does.(control PW.)
The ECU merely provides the trigger at the proper time.

 

That is probably what the IC in the igniter does.(control PW.)
The ECU merely provides the trigger at the proper time.

 

Pulse Width Modulation.

I suspect the IC inside the igniter controls coil current,by means of
varying the pulse width(that PWM).
I haven't looked for any IC app notes to see exactly what they're
doing,though.If anyone has a URL for an app note for these Ics,I'll go
look.

 

Pulse Width Modulation.

I suspect the IC inside the igniter controls coil current,by means of
varying the pulse width(that PWM).
I haven't looked for any IC app notes to see exactly what they're
doing,though.If anyone has a URL for an app note for these Ics,I'll go
look.

 

so where does it adjust pulse width - has to be on the front end, right?
if it was on the rear, the timing would be off. or maybe the ecu
already knows what the igniter's timing characteristics are and adjusts
accordingly?...

 

so where does it adjust pulse width - has to be on the front end, right?
if it was on the rear, the timing would be off. or maybe the ecu
already knows what the igniter's timing characteristics are and adjusts
accordingly?...

 

I think the ECU holds ground on Terminal 4 for the appropriate length of
time, which keeps the igniter driving the coil until ground is removed.
Once ground is removed from Pin 4, the IC switches off coil drive and the
field collapses.

The ECU decides when to apply ground and break it based on the inputs of
various sensors, such as the Crank Angle Sensor. It needs to know current
RPM, cylinder position and crank angle.

Terry is also indicating that the coil is allowed to charge for a longer
time at high RPMs to ensure a fatter spark under harsher conditions.

 

I think the ECU holds ground on Terminal 4 for the appropriate length of
time, which keeps the igniter driving the coil until ground is removed.
Once ground is removed from Pin 4, the IC switches off coil drive and the
field collapses.

The ECU decides when to apply ground and break it based on the inputs of
various sensors, such as the Crank Angle Sensor. It needs to know current
RPM, cylinder position and crank angle.

Terry is also indicating that the coil is allowed to charge for a longer
time at high RPMs to ensure a fatter spark under harsher conditions.

 

yes, but that longer time seems to be determined by the igniter, not the
ecu, if i understand jim yanik correctly. it kind of has to be because
only the igniter is set up to meter the actual flyback, and that is
itself a function of the health of the system.