[s-cars] Identifying Bad Coil

[James Murray (QB/EMC)]

Repost from Craig Cook:

"here is hopefully a quick and inexpensive test for your suspect coil.
Go to Canadian Tire and buy a adjustable spark tester. The one with
the thumb screw that you can manually adjust the gap with.@ $9.00

Lay the coil packs on the valve cover.
Disconnect the coils that aren't being tested.
Use a short plug wire and connect one end to the coil to be tested  and the
other end to the spark tester.
Adjust the spark tester to, I'll say start with the 0.020 gap size. This
will probably equate to  about 1/4 inch on the tester.
Get someone to crank the engine while observing spark.
There should be a nice blue, crisp sounding spark.
Proceed to test all coils to get a baseline as to the spark quality.
Then proceed to adjust the spark tester to a bigger gap while observing the
quality of the spark
After some time and patience you will notice that the spark will turn yellow
and will not have that crisp sound as the others.
Obviously this will be the bad coil.
On a side note you may also want to disconnect the injectors so as not to
load the converter up with raw petrol.

I use this test all the time it never fails. The reason the tester is so
effective is because you're dynamically testing the coil.
As you know when the spark plug is in the cylinder ,the spark has to under
extreme pressure try and ionize the gap.This puts extreme loads on the
igniton coil secondary circuit when your are under load/boost. This tester
will simulate this condition every time.
We have a $30,000 dollar ignition scope at work. I'll still trust this test
over that piece of equipment on any give day."

Enjoy...

/Jamu.


-----Original Message-----
From: s-car-list-bounces at audifans.com
[mailto:s-car-list-bounces at audifans.com]On Behalf Of Brian Powell
Sent: Tuesday, November 16, 2004 2:37 PM
To: s-car-list at audifans.com
Subject: [s-cars] Identifying Bad Coil


I alluded to an ignition problem in my previous email (which
apparently no one read :) ). Under high boost (23+ psi) one of the
coils appears that it fails to generate a good spark. Obviously, this
is causing me much grief to resolve.

Does anyone have any suggestions to how to find the bad coil? I tried
pulling injectors and doing a hard run, but, the ECU throws a fault
when the injector is pulled and boost is limited to the mechanical
wastegate spring.

Any other suggestions? I will probably try to swap out an entire coil
cover with someone just to make sure that it is a coil problem, but,
from there, how do I find the individual trouble coil?

DISCLAIMER TO HEAD OF A STANDARD PIZZO SUGGESTION-- I am not going to
replace all 5 coils. I don't have Evo-type money. :-)

-- 
Cheers,
Brian
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