Honda Car Forum

"Jim Yanik" <jyanik@abuse.gov> wrote
> "Remco" <whybcuz@yahoo.com> wrote
> > Yeah, that is kinda weird how they have the tach input
coming from the
> > ignitor. One would imagine they could have just as
easily taken the
> > signal going to the ignitor (possibly current boost it a
little) and
> > feed it into the tach directly. Less wire and things
that can go wrong,
> > imo...
> >
> > Maybe they did that as a trouble shooting measure or we
can use at as
> > such: This morning I cranked my wife's integra and
noticed that while
> > cranking the tach moves very slightly. Maybe if a honda
cranks and the
> > tach does not move it is an indication that the ignitor
is bad..? That
> > would be an interesting thought.
> >
> > Wonder how Michael is making out with this thing.
> >
> > Remco
> >
>
> I doubt a starter will crank the motor fast enough to make
any significant
> reading on the tach.
> What's the smallest RPM indication on the tach,100 RPM?
> No starter turns the motor that fast.

Doesn't this assume that it's mechanical motion of the
crankshaft or camshaft that actuates the tachometer? If so,
I'm not so sure I buy your reasoning.

I thought it was strictly a digital signal from the igniter
(in particular, its computer chip) that actuated the
tachometer. That is, the igniter computer chip certainly is
not actually sensing degrees of crank- or camshaft rotation.
Instead it receives signals from the ECU to excite the base
of the igniter's transistor yada, in proportion to the rate
at which the primary of the coil is supposed to be
energized. This of course determines the plug firing rate,
which will certainly determine, ordinarily, the engine RPM.
The computer chip "measures" engine RPM through on/off
switching of some kind (and so is digital and not analog in
nature?). I would think that the momentary signals from the
ECU at starting may very well cause something like noise in
the tachometer signal, causing it to jump a bit.

Again, Tegger's site puts a lot of emphasis on watching the
tach to diagnose a bad igniter.

Elle wrote:
> "Jim Yanik" <jyanik@abuse.gov> wrote
> > "Remco" <whybcuz@yahoo.com> wrote
> > > Yeah, that is kinda weird how they have the tach input
> coming from the
> > > ignitor. One would imagine they could have just as
> easily taken the
> > > signal going to the ignitor (possibly current boost it a
> little) and
> > > feed it into the tach directly. Less wire and things
> that can go wrong,
> > > imo...
> > >
> > > Maybe they did that as a trouble shooting measure or we
> can use at as
> > > such: This morning I cranked my wife's integra and
> noticed that while
> > > cranking the tach moves very slightly. Maybe if a honda
> cranks and the
> > > tach does not move it is an indication that the ignitor
> is bad..? That
> > > would be an interesting thought.
> > >
> > > Wonder how Michael is making out with this thing.
> > >
> > > Remco
> > >
> >
> > I doubt a starter will crank the motor fast enough to make
> any significant
> > reading on the tach.
> > What's the smallest RPM indication on the tach,100 RPM?
> > No starter turns the motor that fast.
>
> Doesn't this assume that it's mechanical motion of the
> crankshaft or camshaft that actuates the tachometer? If so,
> I'm not so sure I buy your reasoning.
>
> I thought it was strictly a digital signal from the igniter
> (in particular, its computer chip) that actuated the
> tachometer. That is, the igniter computer chip certainly is
> not actually sensing degrees of crank- or camshaft rotation.
> Instead it receives signals from the ECU to excite the base
> of the igniter's transistor yada, in proportion to the rate
> at which the primary of the coil is supposed to be
> energized. This of course determines the plug firing rate,
> which will certainly determine, ordinarily, the engine RPM.
> The computer chip "measures" engine RPM through on/off
> switching of some kind (and so is digital and not analog in
> nature?). I would think that the momentary signals from the
> ECU at starting may very well cause something like noise in
> the tachometer signal, causing it to jump a bit.
>
> Again, Tegger's site puts a lot of emphasis on watching the
> tach to diagnose a bad igniter.

Makes sense to me. If the ignitor's drive comes from the ECM and
clearly fires when the car is starting (one needs spark, after all),
you should see it on the tach, albeit at a very low frequency.

I had not read tegger's page on the ignitor in quite a while until
today. Seems like you can indeed tell by looking at the tach wheter the
ignitor is bad.
(That site is quite a great resource, isn't it? He's done a hell of a
job on it - can't get over that every time I visit it..)

Remco

"Remco" <whybcuz@yahoo.com> wrote in
news:1135648187.658918.268090@g49g2000cwa.googlegr oups.com:

> Jim Yanik wrote:
>> "Remco" <whybcuz@yahoo.com> wrote in
>> news:1135623154.429489.82800@g47g2000cwa.googlegro ups.com:
>>
>> >
>> > Elle wrote:
>> >> "Remco" <whybcuz@yahoo.com> wrote
>> >> > I stand corrected and didn't mean to mislead
>> >> > anyone.
>> >> > It has been a while since I looked at the ignitor and
>> >> didn't have my
>> >> > manual handy, but that's a bad defense <blushing>
>> >>
>> >> I've looked at the schematic I cited and Tegger's igniter
>> >> site closely at least half a dozen times each this past
>> >> year, and I forgot about the tach output until Michael P.
>> >> mentioned and I re-checked. That the Tach signal comes from
>> >> the igniter doesn't exactly pass the common sense test. At
>> >> least not at first blush, afaic.
>> >>
>> >
>> > Aw, shuks - now you're just trying to make me feel better
>> >
>> > Yeah, that is kinda weird how they have the tach input coming from
>> > the ignitor. One would imagine they could have just as easily taken
>> > the signal going to the ignitor (possibly current boost it a
>> > little) and feed it into the tach directly. Less wire and things
>> > that can go wrong, imo...
>> >
>> > Maybe they did that as a trouble shooting measure or we can use at
>> > as such: This morning I cranked my wife's integra and noticed that
>> > while cranking the tach moves very slightly. Maybe if a honda
>> > cranks and the tach does not move it is an indication that the
>> > ignitor is bad..? That would be an interesting thought.
>> >
>> > Wonder how Michael is making out with this thing.
>> >
>> > Remco
>> >
>>
>> I doubt a starter will crank the motor fast enough to make any
>> significant reading on the tach.
>> What's the smallest RPM indication on the tach,100 RPM?
>> No starter turns the motor that fast.
>>
>> --
> Well, FWIW on my wife's Integra I see the needle bump around zero when
> it starts. It would be interesting to see if it still does that with a
> bad ignitor..
>
> Remco
>
>

Remember that the internal circuit of the "igniter" has an IC to measure
coil current("dwell")and provide the proper drive to the Darlinton current
switch. The tach drive could come from the IC. I haven't yet found the
exact IC number to provide a datasheet to examine,to know for certain.

--
Jim Yanik
jyanik
at
kua.net

"Elle" <honda.lioness@earthlink.net> wrote in
news:iP1sf.861$M%4.706@newsread3.news.atl.earthlin k.net:

> "Jim Yanik" <jyanik@abuse.gov> wrote
>> "Remco" <whybcuz@yahoo.com> wrote
>> > Yeah, that is kinda weird how they have the tach input
> coming from the
>> > ignitor. One would imagine they could have just as
> easily taken the
>> > signal going to the ignitor (possibly current boost it a
> little) and
>> > feed it into the tach directly. Less wire and things
> that can go wrong,
>> > imo...
>> >
>> > Maybe they did that as a trouble shooting measure or we
> can use at as
>> > such: This morning I cranked my wife's integra and
> noticed that while
>> > cranking the tach moves very slightly. Maybe if a honda
> cranks and the
>> > tach does not move it is an indication that the ignitor
> is bad..? That
>> > would be an interesting thought.
>> >
>> > Wonder how Michael is making out with this thing.
>> >
>> > Remco
>> >
>>
>> I doubt a starter will crank the motor fast enough to make
> any significant
>> reading on the tach.
>> What's the smallest RPM indication on the tach,100 RPM?
>> No starter turns the motor that fast.
>
> Doesn't this assume that it's mechanical motion of the
> crankshaft or camshaft that actuates the tachometer? If so,
> I'm not so sure I buy your reasoning.

But during CRANKING,the ECU reads the crankshaft (CK)sensor to determine
firing pulses to FEED the igniter.So,tach pulses are still dependent on the
ECU and engine RPM.
>
> I thought it was strictly a digital signal from the igniter
> (in particular, its computer chip) that actuated the
> tachometer. That is, the igniter computer chip certainly is
> not actually sensing degrees of crank- or camshaft rotation.

No,the crankshaft sensor is doing that.
Spark plugs fire -at a certain position of the piston in each cylinder-
,determined by the ECU,thru the CK sensor.Not by RPM.

> Instead it receives signals from the ECU to excite the base
> of the igniter's transistor yada, in proportion to the rate
> at which the primary of the coil is supposed to be
> energized. This of course determines the plug firing rate,
> which will certainly determine, ordinarily, the engine RPM.

You have it backwards.On *starting*(cranking),the CK sensor reads engine
crank position,and the ECU reads that and calculates the triggers for the
igniter.The starter determines the cranking RPM,the ECU reads it thru the
CKsensor (piston position)and triggers the igniter,where a supplementary
signal is tapped to run the tach.
BTW,the igniter fires the coil *4 times* for each revolution of the
crank,so the tach circuit divides by 4 to get true RPM,or the igniter IC
does that internally.Probably the latter.

> The computer chip "measures" engine RPM through on/off
> switching of some kind (and so is digital and not analog in
> nature?). I would think that the momentary signals from the
> ECU at starting may very well cause something like noise in
> the tachometer signal, causing it to jump a bit.
>
> Again, Tegger's site puts a lot of emphasis on watching the
> tach to diagnose a bad igniter.
>
>
>

The IC inside the igniter is to optimize coil current for hottest spark,and
provide proper base drive for the Darlinton.The coil generates it's HV on
the *shut-off* of the Darlington (that's the "flyback" pulse),not the turn-
on,which is only to *charge* the coil's magnetic field.The IC is there to
insure the coil gets a full charge no matter what RPM,that used to be
called "dwell time",the time the points were closed and charging the
coil,flyback and HV occuring when the points *opened* after charging the
coil.

--
Jim Yanik
jyanik
at
kua.net

"Jim Yanik" <jyanik@abuse.gov> wrote
> "Elle" <honda.lioness@earthlink.net> wrote
> > "Jim Yanik" <jyanik@abuse.gov> wrote
> >> "Remco" <whybcuz@yahoo.com> wrote
> >> > Yeah, that is kinda weird how they have the tach
input
> > coming from the
> >> > ignitor. One would imagine they could have just as
> > easily taken the
> >> > signal going to the ignitor (possibly current boost
it a
> > little) and
> >> > feed it into the tach directly. Less wire and things
> > that can go wrong,
> >> > imo...
> >> >
> >> > Maybe they did that as a trouble shooting measure or
we
> > can use at as
> >> > such: This morning I cranked my wife's integra and
> > noticed that while
> >> > cranking the tach moves very slightly. Maybe if a
honda
> > cranks and the
> >> > tach does not move it is an indication that the
ignitor
> > is bad..? That
> >> > would be an interesting thought.
> >> >
> >> > Wonder how Michael is making out with this thing.
> >> >
> >> > Remco
> >> >
> >>
> >> I doubt a starter will crank the motor fast enough to
make
> > any significant
> >> reading on the tach.
> >> What's the smallest RPM indication on the tach,100 RPM?
> >> No starter turns the motor that fast.
> >
> > Doesn't this assume that it's mechanical motion of the
> > crankshaft or camshaft that actuates the tachometer? If
so,
> > I'm not so sure I buy your reasoning.
>
> But during CRANKING,the ECU reads the crankshaft
(CK)sensor to determine
> firing pulses to FEED the igniter.So,tach pulses are still
dependent on the
> ECU and engine RPM.
> >
> > I thought it was strictly a digital signal from the
igniter
> > (in particular, its computer chip) that actuated the
> > tachometer. That is, the igniter computer chip certainly
is
> > not actually sensing degrees of crank- or camshaft
rotation.
>
> No,the crankshaft sensor is doing that.
> Spark plugs fire -at a certain position of the piston in
each cylinder-
> ,determined by the ECU,thru the CK sensor.Not by RPM.
>
> > Instead it receives signals from the ECU to excite the
base
> > of the igniter's transistor yada, in proportion to the
rate
> > at which the primary of the coil is supposed to be
> > energized. This of course determines the plug firing
rate,
> > which will certainly determine, ordinarily, the engine
RPM.
>
> You have it backwards.

I just omitted the effect of the CK sensor. The main
point--that the signal to the tach is digital and in
response to the ECU signal, and may be sufficiently
electronically yada noisy to yield some jiggling of the tach
upon starting--stands.

> On *starting*(cranking),the CK sensor reads engine
> crank position,and the ECU reads that and calculates the
triggers for the
> igniter.The starter determines the cranking RPM,the ECU
reads it thru the
> CKsensor (piston position)and triggers the igniter,where a
supplementary
> signal is tapped to run the tach.

Yeahbut while starting, well within one camshaft revolution
the ECU is signalling the igniter, whose computer chip is
still signalling the tach.

I'm just saying ISTM there's some kind of signal to the tach
being generated, starting well within one camshaft
revolution.

> BTW,the igniter fires the coil *4 times* for each
revolution of the
> crank,

I believe you mean for each /two revolutions/ of the crank.
It's a four-stroke engine; takes two revolutions for each
piston to have gone through firing TDC (in a four-cylinder
car) once; etc.

"Remco" <whybcuz@yahoo.com> wrote
On Tegger's site:
> (That site is quite a great resource, isn't it? He's done
a hell of a
> job on it - can't get over that every time I visit it..)

Today I was reading his fairly new "online OEM parts
sources" site. Quite an interesting read. I hope to try the
Colorado online parts store he lists sometime soon. Its
shipping appears a little more straightforward and may be
cheaper than Majestic's or SLHonda's. The parts prices
themselves look about the same.

Elle <honda.lioness@earthlink.net> wrote in message
news:EZ3sf.898$M%4.332@newsread3.news.atl.earthlin k.net...

> > BTW,the igniter fires the coil *4 times* for each
> revolution of the
> > crank,
>
> I believe you mean for each /two revolutions/ of the crank.
> It's a four-stroke engine; takes two revolutions for each
> piston to have gone through firing TDC (in a four-cylinder
> car) once; etc.
>
>
FWIW, there's no real reason to "NOT" have it fire. There's just nothing there
to burn half the time.

"Doug McCrary" <DougMcCrary@spamcop.net> wrote
> Elle <honda.lioness@earthlink.net> wrote
> > > BTW,the igniter fires the coil *4 times* for each
> > revolution of the
> > > crank,
> >
> > I believe you mean for each /two revolutions/ of the
crank.
> > It's a four-stroke engine; takes two revolutions for
each
> > piston to have gone through firing TDC (in a
four-cylinder
> > car) once; etc.
> >
> >
> FWIW, there's no real reason to "NOT" have it fire.

Sure there is. For one thing, it would shorten the life of
spark plugs, wires, and coil, potentially by quite a lot.

Weird comment...

> There's just nothing there
> to burn half the time.

"karl" <ottokarl@cognisurf.com> wrote in message
news:1135638874.949310.243180@g44g2000cwa.googlegr oups.com...
> I thought coils last forever. I never had to replace a
> coil, rotor, cup, or wire on any of my cars. I have an
> Accord that soon will be 22. But on this list it is
> very frequently recommended to replace, even on young
> cars, all kind of ignition parts. To me this sounds
> like "it won't do any harm, so lets replace it."
>

The only definite coil failures I've had have been a Nissan that gave one
"pop" when starting, then nothing, and my son's Acura coil that objected to
not having a place for the spark to go. Old time coils practically never
failed; like the old Mopar slant 6s, they didn't have the power to blow
themselves up. Modern coils run at much higher power and are no longer oil
filled, so failures are not unusual. My experience with electrical parts of
all sorts shows the pattern that power handling devices gradually cook
themselves one way or another. 200K+ miles on a coil certainly puts it in
the range of "untrustworthy," and when a contributor I respect says she has
seen intermittent failures in them before they die I think that's reason to
change it out on suspicion... while still investigating other possibilities.

> I have a question about the original message:
>
>> ... suffered a short bout of engine
>> failure. She described it as surging a couple times
>> when she tried to accelerate, then the engine died
>> when she braked. I quizzed her about the tach and
>> she was clear it was jumping rather than swinging
>> with the engine.
>
> Surging - meaning the rpm increased (suddenly,
> audibly?) more than expected, right? With the cars I am
> familiar this would not happen when any of the ignition
> parts fail, to the contrary, they would slow down.
>
I don't think I described it well. The surging was intermittent loss of
power, and of course she instinctively pressed on the gas to compensate. We
all know it rarely helps, but we all do it :-)

A follow-up... the symptoms haven't returned yet. This model has a solid
ground to the chassis near the battery, and the battery negative cable also
takes the ground to the engine, so my concern that we left the ground loose
was unfounded. The ignition switch seems solid, but I'd like to check it
when it is cold, too.

Mike

================================================== ==========
TOPIC: Ignition cut-out
http://groups.google.com/group/alt.a...a5fd8cba927459
================================================== ==========

> == 4 of 11 ==
> Date: Tues, Dec 27 2005 2:39 am
> From: "Elle"

snip

> Instead [the igniter computer chip] receives signals
> from the ECU to excite the base of the igniter's
> transistor yada, in proportion to the rate at which
> the primary of the coil is supposed to be energized.
> This of course determines the plug firing rate, which
> will certainly determine, ordinarily, the engine RPM.



Most interesting.



..