Ignition/Starting Problem with 1994 Miata
Danny Snyder
The car was parked in the garage after coming home. Ran fine, etc. The
following morning, the car wouldn't start. There was no fuel being
delivered to the engine and no spark either. Upon testing, following
diagnostic procedures in the factory shop manual, we determined that the
crankshaft position sensor was dead. Got a new one ($315!! + tax),
installed it and things are better. All 4 injectors now fire as they're
supposed to. Cylinders 1 & 4 spark plugs fire correctly. Cylinders 2 &
3 do not fire at all. We've tested both ignition coils; both check out.
There's continuity between the PCM and the coils. At this point,
about all we can come up with is a problem w/ the PCM, but it too
appears to check out.
I'm wondering if anyone else has experienced this problem and if so,
what the solution was.
Thanks in advance,
Danny Snyder
dan...@trustnoone.org
Adam Payrot
checked out fine according to what the books and others said. So, I tore
everything apart, even checked the ECU. Everything was fine. So, went back
to the coils. Pull the #1 spark plug, and then put it in the connector on
the wire. Ground the plug to the valve cover, and then have somebody switch
the key to the start position. You should see one small spark as everything
else under the hood clicks. Re-install #1 spark plug and wire. Then repeat
the process w/ #2. My problem was that #1 and 4 fired, 2 and 3 didn't. All
tests checked out, except this one. #2 should not spark for that
split-second, and that coil (the one on the driver's side of the car) is
dead. You can pick up a whole coil unit, used, for $100 from the mazda
recyclers (www.mazdarecycling.com). That would be both coils and the
bracket. FWIW, I have an extra coil from when I had to do this, if you need
it. I live in the DFW area (TX).
Adam Payrot
Danny Snyder <sny...@austin.rr.com> wrote in message
news:3CB083F3...@austin.rr.com...
Mr Sot Sot
> 3 do not fire at all. We've tested both ignition coils; both check out
DId you swap the coils? Put the 1&4 coil in the 2&3 position and vice versa?
(You can also flip the wiring harness plugs and plug wires, but I prefer the
former since there's less variables to consider). If the problem still exists
on the same side, then the trigger from the PCM is dead and that probably means
you need to look at the PCM and its connector.
Danny Snyder
between the two coils. I get spark from both coils. The problem
follows the harness for the 2/3 coil. At the very least, I have
continuity between the harness for the PCM and the harness for the coil
as well as the proper voltages at all the pins concerning ignition as
indicated by the shop manual. Any more ideas? I'm baffled & don't have
any info. on how to check the PCM's circuitry, if that's even possible.
My next step is to replace the PCM. That's about all it can be,
unless I'm missing something.
Thanks again,
Danny Snyder
dan...@trustnoone.org
Matthew Russotto
Danny Snyder <sny...@austin.rr.com> wrote:
>supposed to. Cylinders 1 & 4 spark plugs fire correctly. Cylinders 2 &
>3 do not fire at all. We've tested both ignition coils; both check out.
> There's continuity between the PCM and the coils. At this point,
>about all we can come up with is a problem w/ the PCM, but it too
>appears to check out.
>
>I'm wondering if anyone else has experienced this problem and if so,
>what the solution was.
Igniter? I was under the impression that the igniter and coils were one
assembly, though.
--
Matthew T. Russotto mrus...@speakeasy.net
=====
Every time you buy a CD, a programmer is kicked in the teeth.
Every time you buy or rent a DVD, a programmer is kicked where it counts.
Every time they kick a programmer, 1000 users are kicked too, and harder.
A proposed US law called the CBDTPA would ban the PC as we know it.
This is not a joke, not an exaggeration. This is real.
http://www.cryptome.org/broadbandits.htm
Danny Snyder
manual), the igniter and coils are one assembly. Both coils generate
spark, so I doubt there's any problem with the coil assembly.
-Danny
Adam Payrot
If it ends up being that, I will have one that I had planned on selling
anyways.
Adam Payrot
Danny Snyder <sny...@austin.rr.com> wrote in message
news:3CB0F2EB...@austin.rr.com...
Paul
I swap input plugs. The problem is intermittent and only on start.
I connected a tacho-type multimeter - no signal on input plug.
I went looking for the computer behind the seat (as the Haynes said)
but eventually found it in the passenger footwell - must be a UK
thing! It's protected by shear bolts so I couldn't check continuity.
It's booked in to a Mazda garage later in the week - I'm worried
they're going to sting me for a new computer. Can you get intermittent
computer problems? Anything I can look at with the diagnostic
connector?
Matthew Russotto
Paul <paul.go...@aircom.co.uk> wrote:
>I also have exactly this problem (UK 1997 1.8). 2+3 not firing unless
>I swap input plugs. The problem is intermittent and only on start.
This is the problem I had on my 1999. It was a bad coil. Or at least
they replaced the coil and it hasn't re-occurred. It would occur on
warm start, usually after the car had been sitting 30 minutes to an
hour.
Mr Sot Sot
>between the two coils. I get spark from both coils. The problem
>follows the harness for the 2/3 coil.
A good shop would use a scope to look for the trigger voltages at the ECU
(PCM) connector and replace it if the 2/3 signal is bad.
I heard factory price new is around $600, but they used to be available used
for under $150 from people who had gone with aftermarket units for
turbos/superchargers. Ebay has driven up the price,
If you go used, verify that it is the right replacement. I believe there was a
design change in the coils, but don't know if it impacted the computer..
tooloud10
news:20020408125237...@mb-me.aol.com...
> >Unfortunately, I already tried that. I swapped the wiring harnesses
> >between the two coils. I get spark from both coils. The problem
> >follows the harness for the 2/3 coil.
>
> A good shop would use a scope to look for the trigger voltages at the ECU
> (PCM) connector and replace it if the 2/3 signal is bad.
>
> I heard factory price new is around $600, but they used to be available
used
> for under $150 from people who had gone with aftermarket units for
> turbos/superchargers. Ebay has driven up the price,
Don't bet on the eBay part--one week before needing it, I would have been
able to buy an ECU for my '90 Talon for $45 on eBay. Of course, when the
capacitors in the ECU blew, there were none for auction and I was forced to
pay $165 for one. That was considered cheap at the time.
> If you go used, verify that it is the right replacement. I believe there
was a
> design change in the coils, but don't know if it impacted the computer..
--
tooloud10
Remove nothing to reply...
Paul
My car's with the garage, they currently suspect ECU. What price
should I accept if it turns out to be dead.
They've said they can get a used one - anyone know a reasonable price
(in the UK preferably).
Danny Snyder
shipping. As it turns out though, my ECU is fine. The replacement
crankshaft position sensor was defective. I'll be installing another
one today and whill hopefully have the car running this afternoon.
-Danny
Danny Snyder
was defective! A little more detail on my experiences here for those
interested. If I think about it, I'll try to snap a couple pictures of
the internals of the sensor & put the up on the web for clarification
purposes.
The sensor has two rotors that are driven by the camshaft. One has two
prongs sticking up off of it; the other has four. For each rotor, there
is a magnet and a pickup. As the rotors are turned by the cam, the
magnet field being interupted causes a pulse to be generated by the
sensor. There's two output pins on the sensor- one for each pickup.
I'm not sure if there's always output from the pickups and the magnet
field being interrupted interrupts the signal- thereby generating a
pulse. Or the magnetic field being interrupted may cause the pickup to
generate the signal that is sent to the PCM.
With the pickup for the 4-pronged rotor working, fuel injection works on
all cylinders and you will get spark on cylinders 1 & 4. Cylinders 2 &
3 will not have spark. The first replacement sensor was defective out
of the box- the pickup for the two-pronged rotor was broken. The got a
constant signal from the sensor- no pulses. I got four pulses per
revolution as expected from the other sensor output pin.
After getting another sensor and installing it, the car now starts &
runs just fine. Now I just have to deal with one of the heater hoses
gushing coolant.... :-(
Hope my experience is able to help someone else out with a similar
problem. Again, this is for a 1994 Miata, so other model years may not
have the same problems or solutions to the problems. BTW, the PCM was
fine. Didn't need to replace it afterall....
-Danny
Paul
again to tell me that the ECU was fine and ... it was the camshaft
sensor!! (1997 1.8)
They're fitting a new one tomorrow but they've had the car running on
a borrowed one.
It hasn't rained for the 3 weeks the car has been dead - quite unusual
for March/April in UK. I knew the car was nearly fixed yesterday -
it's started raining!