Checking ignition coil with dwell meter

In the faq, it says you can test the ignition coil by hooking up a
dwell meter to the negative coil terminal. On a 91 accord, how do I do
this?

Do I take off the dist cover and rotor and clip it onto the terminal.
Do I then crank it like that. Won't thank damage something, as the
spark the coil generates will not have anywhere to go? Should I unplug
one of the wires going into the disctributor?

What is a good dwell. If I have an internitant problem, would this
identify it or would I have to wait until the problem reproduced.

I couldn't find much info about this in the gourp or online.

Thanks!

 

For fairly exacting instructions for testing the 91 Accord's ignition coil,
see www.autozone.com. Put in your model's info, click on the links to the
FREE repair guides, go to Engine Electrical, Electronic Ignition, Diagnosis
and Testing. There you will see the following and more:

---
See Figure 16

The ignition coil is contained within the distributor. With the ignition
OFF, remove the distributor cap.

Remove the screws securing the black/yellow wire and white/blue wires from
the terminals. The black/yellow wire is connected to the primary positive
terminal and the white/blue wire is connected to the primary negative
terminal.

Measure resistance between the terminals. Resistance should be between
0.6-0.8 ohms.

Measure the resistance between the primary positive terminal and the
secondary terminal. Resistance should be 12,800-19,200 ohms.

Fig. 16: Coil terminal designation on 1990-91 Accords

 

I did this, but the faq at
http://www.tegger.com/hondafaq/startproblems.html#badcoil says the
following.

How to tell if your coil is bad:
"The simple test to diagnose most no-spark conditions is this: Connect
a dwell meter to the negative coil terminal and to ground. Crank the
engine: No dwell, bad igniter; Dwell but no spark, bad coil.

Would this give me more information then the above test. Specifially,
would it help identify if this is the cause of an intermittant not
starting problem.

 

Did the resistances all check out?

This unofficial FAQ site at times uses input from random posters (like the
above) whose validity one _cannot_ judge. It's particularly annoying to note
that the FAQ credits a (definitely random) poster named "Oak" as
contributing this. In fact, Oak did not post this; some other person did,
per a groups.google search. It's not clear what this other person's
credentials are, either. I have not seen this test in official Honda
manuals.

Have you described this starting problem here yet?

Please do.

Does it occur on cold starts? After warmed up? After warmed up, then turned
off, then when re-starting, it doesn't start?

Is the engine RPM erratic at stop signs, with the engine running?

Does it seem like it's going to stall, and the only way to stop this seems
to be to hit the gas pedal?

How old is the coil on your 91 Accord? How old is the igniter? (Miles and
years, please.) Same question for spark plug wires and plugs.

For now, if the coil passes the test I posted, I would start looking at
other things.

Very common causes of early 90s (in particular) Honda no starts, assuming
fuel filter, air filter, plugs, and ignition wires are okay:

Bad main relay
Bad ignition switch
Bad distributor ignitor
Bad distributor coil

There is a test for the ignitor at the autozone site I gave earlier.

You might get some ideas from the unoffical FAQ site, but I would not bank
on its advice (if you can quickly extract it from all the painfully not cute
colloquialisms that pollute it).

Hang in there. I'm sure some of the regulars will leap in and offer further
suggestions. For now, use the online manual at Autozone and try some of its
tests.

 

How do we judge /your/ validity?

Would you rather be annoyed than be the architect of correction? Who's the
real culprit then? John Ings put that part in, not me. If it's
misattributed, I'll fix it.

I think it's pretty clear to all that I welcome corrections.

By the way, I just checked with a very knowledgeable correspondent of mine
and he says the test procedure in the FAQ is sound. This is the same guy
who helped put together the igniter section. I'm just waiting on
clarification from him on whether or not the coil needs to be disconnected
for the test.

You won't find the Main Relay diagnoses and fixes in Honda manuals either.
There's a /lot/ of stuff you won't find in Honda manuals either, for that
matter.

 

Random posters can provide tips or trick that publishers won't
publish. Any wrong and unsafe tips will and can be disputed -
that's the nature of USENET. Teggar's FAQ may actually be current
than publications.

I've read a few igniter tests at Autozone only to find inacurate input
tests. This same material is published in the Helm manual which can
be as outdated and not perfect. Teggar's FAQ uses a dwell meter,
which isn't required, which in fact be replaced with a better cheaper
tool, a test light.

 

Yes the FAQ is more accurate than simply checking the
resistance. The bad part is that a dwell meter is much more
expensive than a test light and does exactly the same result
on this test.

What you want to do is to remove the negative side of the coil
and attach it to your test light (possibly 22-50 watts bulb would
be better.) If you don't want to remove any wire then attach a
ground lead to the secondary port on the coil to prevent coil or
igniter damage.

 

You mean tips like, testing the coil by sticking your tongue on the
output tower while cranking the car?