Faulty ignition modules usually just stop. After all, it's just a switching
circuit; it either switches or it doesn't. Well, actually some modules can
be got going again by waiting till they cool down, or by knocking them,
but anyway,
the most common fault is that they start stopping when hot, then get
progressively worse until the car won't even start when cold.
Others just suddenly die and that's it.
Actually, lately I've had
more new modules than old ones to repair. Now this is the opposite of what
you would expect, but the newer modules are not built as robust as the older
ones and are dieing earlier from structural failure than component failure.
Some of the newer ones are only lasting about 5 years.
Hence lately I'm getting reports of cars not starting again after they've
turned them off, rather than dieing while they are running and hot.
If your car is misfiring or running rough then it is most probably NOT the
module.
Check the usual things first: spark plugs, ignition leads, distributor cap
& rotor.
On a Commodore 5.0 I would suggest changing:
- Distributor cap every 120k or 8 years.
- Rotor every 100k.
- Plugs every 20k.
- Leads, at least every 60k.
- Coils should be replaced before 200k. Yes they DO wear out!
The insulation is constantly being chewed at by the spark and the older oil
filled ones have been known to burst and catch fire. I change mine at 140k
- but that's just me! However, if in doubt, change it!!! Since if the
insulation starts deteriorating and shorting internally then the coil will
start to draw more & more current this will ultimately cause the module to
fail and it may fail by going short-circuit, which in turn will "finish off"
the coil. Then you'll have a situation where you replace the coil only to
have it toasted again by the module.
I run mine on LPG so I have to change the ignition leads every 45k because
on LPG, if a lead ever dies, the LPG will start exploding in either the
intake manifold or exhaust.
Distributor caps have a habit of suddenly corroding. One year it looks fine.
You check it a year later and it's shot.
When changing rotors always keep the old rotor to compare against.
I've seen some after-market rotors that are shorter by up to nearly 1mm.
This is equivalent of a 2mm spark plug gap!
Yes - You probably will get an electric shock if you touch the coil driver
device on top of the module with the engine running - this is normal.
Avoid touching it!
What you are feeling is the fly-back from the coil. When it fires you get
around 25,000V out the secondary side, but you also get a high
voltage spike (330V +/- 30V) back out the primary (12V side), which the
ignition module must handle.
WARNING:
DON'T LET THE case of the coil driver short to the chassis or it will turn
your coil fully on. This will burn out the coil, it's only designed to be
pulsed. The device should be coated to protect against this - if not,
be careful.
By the way, the fly-back will increase if the coil has a harder time getting
rid of the energy it has created when it's fired, such as if your spark
plug gap increases or the ignition leads get old. This reduces the lifetime
of the ign module - so get any electrical problems fixed fast!
So ensure you don't spark test the car by seeing how far you
can get the spark to jump. This is not good for it. With electronics now
firing the coil, gone are the days when you do that!
Ignition modules will generally start to fail at anywhere from 7 yrs to 15 yrs
depending on how much you drive the car and how hot the module is
getting in the engine bay. It is recommended that you carry a spare module
in the boot of your car just in case. I have seen one fail in less than
5 years. If you are over 15 yrs already then don't schedule a round-Australia
trip in your car, as you are on borrowed time!
If your coil has died, FIRST CHECK THAT THERE ISN'T A SHORT CIRCUIT between
the two fat end pins of the module's 6-pin connector. There should not be a
short circuit between pins 1 & 6. A short circuit there means your module
is holding the coil on.
In the past I have received a few Bosch modules via exchange that appear
to have been damaged by voltage spikes.
These can occur in the car by not having a good battery or
by not having the battery terminals clean. The car battery has a second
important function in the car, it is not just there to start the car.
It shorts out voltage spikes from the alternator.
This is why the alternator is wired direct to the car battery before the
wiring goes off to the rest of the car.
(Something to watch out for if you ever remove your voltage regulator -
disconnect the battery first!)
How does a voltage spike occur?
When something that draws heavy current is turned on, such as your headlights,
the electric field in the alternator ramps up to deliver the extra current.
When the headlights are turned off again this electric field, which is
sitting in an inductive system, cannot just disappear instantly,
it has to decay away.
That can leave two or three hundred watts of power with suddenly no
where to go. Watts = Volts x Amps, so if the current suddenly decreases
then the voltage will suddenly increase (due to the laws of physics)
to maintain the field.
It's called an Alternator Load Dump. Alternator Load Dumps
get shunted into the car battery to be shorted out.
Weak batteries and damaged voltage regulators can cause irregular voltages.
Disconnecting a battery from a running car is a big "NO! NO!". The idea of
doing this went out the window with the event of car electronics which was
incorporated into cars about 2 decades ago, but not many people seem to
have changed with the times.
The original equipment modules have a voltage spike immunity that I'm not
particularly happy with, so if you think you may require improved voltage
spike tolerance then have a look at my Profield Performance Module auction.
These have the spike immunity increased by 40 volts.
I also have VR & VS 5.0 V8 automatic transmission computers (PCMs) available,
both HSV and standard.
Memcals include:
BFPL (VR HSV), BLCC (VR V8), BLCJ (VR V8), CKUP (VS HSV), BWCU (VS V8).
Ok, time to forget all that technical stuff, it's time for the.....
*** TOASTED MODULE AWARD ***
This highly coverted award is given to the person who single-handedly destroys
the most components in their ignition module. A new winner has emerged who has
simply blitzed the field, despite the number of people who have tried.
CONGRATULATIONS GOES to..... DM (aka "Conan The Destroyer") from HIGHFIELDS
in QLD!!!!!!
With no less that 6 dead transistors and both ICs, DM is the clear and
outright winner. And, as a bonus, he is also the very first person to toast
the ICs.
DM -
I'd just like to thank my family,
the many shorting and cross earthing wires,
the dud battery that poured acid everywhere,
a now damaged alternator regulator and most of all the battery leads that
came lose while driving because I forgot to tighten the damn things up!
Most of all I'd like to thank the fuel pump for alerting me to the danger
even though I just ignored it anyway. Lastly I'd like to thank you,
the good people for nominating me for this award. I dedicate this to you!
Well done DM! We wish you all the very best in the future production of chaos
and mayhem in the field of car electrics.
ooooOOOoooo
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