I've got a 1991 Accord that won't start. It ran fine daily, sat parked
for a couple of days, and now won't start.
- No Spark on any plug.
- Cranks just fine.
- Fuel pump cycles when the key is switched on.
- Check engine light comes on, then shuts off after a few seconds.
- Rotor turns.
- 0.7 ohms resistence across the low side of the coil (low voltage
- High side of the coil (post to ground) is open (infinite resistence).
My initial guess is that the coil is bad. That just seems so unlikely
considering it ran just fine when it was parked last week. If it died
while running that diagnosis would be consistent.
Any suggestions? I'm out of my element here.. I'm more comfortable
with Honda motorcycles and GM/Chrysler cars.
Definitely sounds like an open coil.(the infinite secondary resistance
measurement is the glaring clue)
You could also have some bad plug wires,that allowed arcing and extra
strain on the coil.Or from condensation moisture built up while sitting.
Time for new coil,distributor cap/rotor,and HV wires.
use of OEM parts is highly recommended.
Try the distributer cap. Condensation might have caused the copper
connections inside to become coroded. Hard to get spark through the
green stuff. I had the same issue with my 89 Mercedes 300E.
Jim Yanik wrote:
I think it WAS flooded (see owner's manual for how to start) but now the
coil (or is it igniter) is shot because you spun it with the plugs
disconnected. When the high tension has nowhere to go, it goes
internally and blazes new trails.
The flooding is caused when an injector dribbles overnight and all the
fuel in the pressurized in the rail drips into one cylinder. The cure
for the injector is cleaner, twice a year, or gasohol now and then.
www.tegger.com has way more help about igniters.
Specs are 0.6 to 0.8 ohms and 12,800 to 19,200 ohms,
respectively, so the resistance checks suggest the coil is
My money's on the problem being the igniter or some other
ignition part. The igniter costs under $100 from OEM online
parts sites and is not hard to replace, given your other
How many miles on car? Years and miles on coil and igniter?
If originals or non-OEM, again, strongly suspect one of
When was the car last tuned up (new plugs, wires,
distributor rotor and cap, fuel filter, air filter, timing
check, bottle of Chevron Techron in fuel tank)? Were OEM
ignition parts used?
A good site for these and other candidate problems for your
situation, including further checks you can do on the coil
www.autozone.com has a free online manual (with many factory
service manual excerpts) for your car that also has
troubleshooting procedures under the "Engine Electrical"
How does "infinite resistance = 12.8K to 19.2K ohms?
IMO,infinite R = OPEN = bad coil.
Of course,he should be measuring from either one of the LV tabs to the EHT
output terminal(post) for that secondary resistance reading,as the igniter
will not be grounding the coil.
Most any meter should be able to read 200K ohms full scale,up to 2 megohms
FS is very common.
My $3 Harbor Freight DMM has a 2 Meg range,my 4.5 digit DMM goes up to 20
Meg.My analog Simpson 270-3 goes up to 2 meg FS.
I was indeed thinking of an old analog meter my dad still
keeps around, dating from I bet the 1950s or possibly
earlier. (He bought me a digital multimeter a few years
ago.) But I haven't used his old analog enough to realize it
most likely goes up to at least the high k-ohm range. On the
third hand, I reckon it's pretty rare for anyone the least
bit handy with cars these days to be using an analog meter
these days with regularity.
Thanks for explaining all, Jim Y.
I measured from the high tension post to ground and it read (according
to my highly accurate Radio Shack auto-ranging digital multimeter) to
be completely open. That's normal? I was guessing something in the
I agree, but I'm afraid at this point that it could have damaged the
coil as well. For GM cars I always recommend replacement of the
ignition module as a preventative even if it still works.
It's the girlfriend's car which she bought from a sleazy used car
dealership with 170k miles on the clock. Who knows when or if it has
ever been maintained or tuned up. The inside of the cap looked about
as bad as I've ever seen. Surprisingly it ran very well, but it is a
I'd like to use OEM replacement parts but I *must* get the car running
this weekend (she's driving MY new truck to work right now!) so it'll
get whatever Autozone has to offer.
Thanks for the link. That's a good site. Wish I had a dwell meter to
perform the recommended test. I'm contemplating plugging my
oscilloscope into the low side to look for pulses before condemning any
$100+ ignition parts that I don't fully understand.
I'll post back what ends up fixing it - might help someone else
someday. Thanks for the advice!
I misread the manual, for one thing. I think what you are
measuring is the resistance of a circuit with a capacitor in
it. See the top drawing at
http://home.earthlink.net/~honda.lioness/id5.html . Jim Yanik
can chime in
here and see if I have it right now.
What the manual specifies to check is the resistance between
(1) the high tension positive terminal (called terminal "A"
in the manual, and having a black/yellow wire connecting to
it) and (2) the secondary terminal (= the "coil tower" in
some manuals = the part of the coil going to the distributor
cap and plugs, etc.). It is this resistance that is supposed
to be in the kiliohms range.
Towards the bottom of the following site, the procedure is
described, with specs:
Some fellow posted in the last year or so that for something
like $200 for parts, he slapped a new Autozone distributor
(housing, igniter, coil, the works) into his Honda and it
fixed it right up.
It's not a long term fix, IMO, because the OEM parts are
superior, from my experience (91 Civic, original owner,
myriad distributor problems) and reading here.
He said he was measuring to -ground-,which only works if the igniter is
grounding the coil,which it does not do with the car off.
(grounding the ign.coil charges it up,and ungrounding the coil afterwards
generates the spark voltage.That condenser is actually part of the HV
Actually,on a 20K or 200K meter range,it does not matter which side of the
primary he measures to the center post(wht/blu or blk/yel to post),as the
primary is so low a resistance,the meter sees it as a short,and only
measures the High Tension(HT) side of the coil.
That's after measuring the low side of the coil so you know it's not open.
I suspect it's rare the low side (primary) of the coil has any problem.
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