[s-cars] Testing coil

Wed Jul 20 22:08:41 EDT 2005

Decided to do that since I don't get constant all way smooth acceleration 
after tune up.

I've got adjustable spark tester. Don't have piece of plug wire - so I 
inserted tester into plug and pushed it a little fixing in that position 
using some electric tape :)

Disconnected injectors.

I'm ready for test - but have no idea how to "disconnect other coils"

Is it critical at all? Can I damage them if crank without plugs?

I guess my question is "how do I disconnect coils?"

And what would be good ground to connect to?

>From: "James Murray (QA/EMC)" <james.murray at ericsson.com>
>To: mlped at qwest.net, "'idemkovitch at hotmail.com'" <idemkovitch at hotmail.com>
>CC: s-car-list at audifans.com
>Subject: RE: [s-cars] Urgent.. UrS4 vibrates when turbo should kick in...
>Date: Mon, 20 Jun 2005 12:12:19 -0500
>
>Ivan, you need to test for a coil that failing, still working but giving up 
>the ghost... you're not looking for a coil that is not functioning (that's 
>a easy test). Check write up on SJM 
>http://www.sjmautotechnik.com/S4_Ignition.htm,  but you might want to also 
>consider this test:
>
>Repost info:
>"
>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. "
>
>___
>Locating a bad Coil
>
>A bad coil usually is indicated by an intermittent miss which appears only 
>under boost conditions.  If the miss happens at all times, even at idle, 
>then the problem is likely something else, probably the PSO (Power Stage 
>Output).
>
>To isolate the bad coil so that you know which of the five to replace:
>
>Start the engine and disconnect an injector.  I suggest starting with 
>number 1 but that's up to you.  This will cause the engine to have a 
>full-time miss.  Drive the car a couple of hundred yards part of which 
>should be at WOT (wide open throttle).  This will produce some boost and 
>any additional misfire will be readily apparent.  Now reconnect #1 and 
>disconnect #2 and drive the car again.  Repeat until the added miss doesn't 
>happen.  That coil is the bad coil.  If it's injector is disconnected the 
>cylinder will not fire but at boost the remaining four will continue to 
>fire and there will be no additional miss showing up at WOT.
>
>It is as easy to tell the difference between a five cylinder engine firing 
>on only four and that same engine firing on only 3 cylinders as it is to 
>tell when a five cylinder engine is firing only on four cylinders.
>
>Once the bad coil is identified you can now replace the coil.  Before 
>finalizing the installation make the electrical connections and do a good 
>test drive to be sure the miss is gone before shortening the leads to the 
>coil.  This is just in case you misjudged something.
>
>____
>
>-----Original Message-----
>From: s-car-list-bounces at audifans.com
>[mailto:s-car-list-bounces at audifans.com]
>Sent: Monday, June 20, 2005 1:03 PM
>To: mlped at qwest.net
>Cc: s-car-list at audifans.com
>Subject: RE: [s-cars] Urgent.. UrS4 vibrates when turbo should kick
>in...
>
>
>So, statement that "coil is working or not" from
>http://www.audifans.com/twiki/bin/view/Audi/TestingForSpark
>is not correct? Like I said problem is intermittant. It happens rarely now.
>But under WOT acceleration I alsmost always have couple of "jerks".
>
>
> >From: "mlp" <mlped at qwest.net>
> >Reply-To: <mlped at qwest.net>
> >To: "'Joe Pizzimenti'" <joe.pizzimenti at gmail.com>,  "'Ivan Demkovitch'"
> ><idemkovitch at hotmail.com>
> >CC: s-car-list at audifans.com, keith at maddock.com
> >Subject: RE: [s-cars] Urgent.. UrS4 vibrates when turbo should kick in...
> >Date: Sun, 19 Jun 2005 22:15:15 -0600
> >
> >Actually Joe, I believe Brian Powell has a rather interesting coil 
>tester.
> >Perhaps he will chime in with his methodology (I think there is something
> >of
> >an art to reading how far, or in the case of a not so good, unhealthy 
>coil,
> >how not so far, a spark will jump.   From an email exchange with Bruce 
>Mock
> >May 31 links ....
> >
> >
> >When in doubt (if they are still in business ~ I think they've gone 
>through
> >a couple of Chapter 11's) .... the old J C Whitney, .... or Army surplus
> >:-)
> >or ...
> >
> >?  http://www.etoolcart.com/index.asp?PageAction=VIEWPROD&ProdID=538
> >
> >although Brian's device was pretty trick in that it allowed the gap 
>between
> >the contacts to be progressively lengthened so that one could build a
> >relative basis from coil to coil of spark/coil strength.  In fact it 
>looks
> >a
> >lot like the device in photo #2 at
> >
> >
> >http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&tc=photo&rd=1&item=
> >4542220859&category=43989&sspagename=WD1V or
> >
> >	http://tinyurl.com/75h3o  or
> >
> >	http://tinyurl.com/9yh7m
> >
> >Ain't the net amazing?
> >
> >
> > >-----Original Message-----
> > >From: s-car-list On Behalf Of Joe Pizzimenti
> >
> > >minutes... No way to really "check" the coils, AFAIK, just
> > >replace the spark plugs or even try tightening the gap on them
> > >to see if that gets you anywhere.
> > >
> > >Joe
> > >
> > >On 6/19/05, Ivan Demkovitch <idemkovitch at hotmail.com> wrote:
> > >> Ok.
> >
> > >>
> > >> So, I will replace spark plugs. How can I check coils??
> > >>
> > >> Thanks,
> > >> Ivan
> > >>
> >-----Original Message-----
> >From: mlp [mailto:mlped at qwest.net]
> >Sent: Tuesday, May 31, 2005 7:56 AM
> >To: 'Mock, Bruce J (Bruce)'
> >Subject: RE: Re: [s-cars] RE: Baffled over boost
> >
> >HTH
> >
> >Mike
> >
> >
>
>
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