[s-cars] Urgent.. UrS4 vibrates when turbo should kick in...

Mon Jun 20 13:13:06 EDT 2005

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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