Ignition cut-out

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" wrote in news: snipped-for-privacy@g49g2000cwa.googlegroups.com:

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.

"Elle" wrote in news:iP1sf.861$M% snipped-for-privacy@newsread3.news.atl.earthlink.net:

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.

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.

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 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" wrote

input

it a

we

honda

ignitor

make

so,

(CK)sensor to determine

dependent on the

igniter

is

rotation.

each cylinder-

base

rate

rate,

RPM.

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.

triggers for the

reads it thru the

supplementary

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.

revolution of the

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" wrote On Tegger's site:

a hell of a

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.

FWIW, there's no real reason to "NOT" have it fire. There's just nothing there to burn half the time.

"Doug McCrary" wrote

crank.

each

four-cylinder

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

Weird comment...

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 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

snip

Most interesting.

"Michael Pardee" wrote

power to blow

are no longer oil

electrical parts of

gradually cook

certainly puts it in

respect says she has

that's reason to

other possibilities.

Toss in that Tegger put this item's troubleshooting and replacement, with quite a lot of detail, into his FAQ. Meaning the coil's failure is reported quite a bit here.

My 91 Civic's first coil lasted ten years, 120k miles. My one non-OEM coil lasted less than two years, about 35k miles. Firestone charged me an arm and a leg for that non-OEM coil, too.

'Course, let me be the first to point out that non-OEM ignition wires may have played a role. Tegger's 1991 Integra, at over 240k miles IIRC, is still on its original coil. He appears to take fastidious care of his ignition electrical parts (rotor, cap, wires, plugs all replaced at five years by him, all OEM IIRC). A lesson for us all, IMO.

I read the other day an article by Auto tech writer Larry Carley. He also reported that not taking good care of ignition wires will shorten coil lives.

This might not solve your daughter's car's problem. Again, it's just where I would start. Though I would have taken resistance measurements, per the manual's specs, on the old coil before replacing it, too. Not that you have time over a possible holiday to deal with this.

"Elle" wrote in news:EZ3sf.898$M% snipped-for-privacy@newsread3.news.atl.earthlink.net:

Meaning there's ON and OFF and no inbetween.

The jitter would be due to normal timing variation of firing pulses from the ECU/CKsensor system,not from "noise" which would not affect a digital signal.(after all,it's a closed-LOOP system.) And the inertia of the digital to analog conversion to drive the tach needle smooths out jitter. The tach jitter is essentially meaningless,as the motor is not turning fast enough to give a true indication of RPM,RPMs being below the minimum calibrations of the tach dial. Note I previously said "significant reading".

Actually,I think the RPM calibration begins at a few hundred RPM,then linearly increases from there.

(well,the igniter chip is not a "computer" chip,it's analog;a current- sensing comparator to insure a full coil charge,that "dwell" stuff.)

Yes,the tach pulses get generated,but not enough pulses or fast enough to be significant.I haven't gotten a look at the specific circuitry of the igniter IC to be sure that tach pulses would not be generated even if the Darlington was blown and no current being switched thru the coil.The ECU could be triggering the IC and tach pulses passed on,but no Darlington drive or a dead Darlington.

You got me there.

"Jim Yanik" wrote

tach

firing pulses from

Sure. I was being loose with "noise" and probably crossed the line to inaccuracy.

AFAIC, noise can be a problem, regardless of whether the system is closed loop or open loop.

For example, the ignition system has a radio noise condenser in it (meaning, I hope as you know, this condenser reduces interference with the ECU, the car radio, and probably the igniter's transistors. Reports from two of our regulars here are that this condenser's removal or aging can definitely adversely affect ignition and so engine performance.

drive the tach

not turning fast

the minimum

Meaningless as far as indicating actual RPM. Meaningful as far as possibly using it to diagnose an igniter failure. Or so it seems to me for now.

I don't agree or disagree with the rest. My only interest was proposing that the Tach response could give an indication of igniter mis-operation. No disrespect intended; I prefer to get the bulk of my electronics lessons from other than Usenet. It's too hard to communicate important detail on internet boards.