J. Patterson

At Barber this weekend I lost 2 coilpacks. First one was 10 minutes into my first session. Cyl #3. Found one I could borrow from Craig Smith who had lost his Manifold to Turbo gasket, and was good enough to let me have one of his to get me going. Oddly after one session, the coilpack I borrowed from him failed. He was good enough to let me have another of his to replace it. I had never had a coilpack failure before and 2 in one hour of track time seemed too much of a coincidence. I Had never tracked the car before this week with the boost machine. I was set to peak at 23psi and of course it tapered off to about 19psi at 6000 + rpm. After the 2 coilpack failures I turned the boost down to about a 20 psi peak and had no further problems for the weekend. My question is does additional boost cause coilpacks to work harder , or was my experience just coincedence?
FWIW it seems that my car runs just as well with a 20psi peak as it does with 23psi. The Corvette and the S8 in my group could walk away on the straights , but not too badly considering the displacement difference.
Thanks in advance for any info.
BTW I have 4 new coilpacks on the way. I was lucky this weekend that Craig had mercy on me. I'll be prepared in the future with my own spares.

TTschwing

CP Harness degradation and eventual shorting has been showing up....<ul><li><a href="https://forums.audiworld.com/tt/msgs/1566241.phtml">Follow the thread..</a></li></ul>

J. Patterson

First failure occured on cyl # 3 (hard to access with that bracket bolted on top). I moved the questionable coil pack to cyl #1. The fault code moved to #1 also. So- I put the borrowed coil pack on cyl # 1 and ran a session with all good. Next session the borrowed coil pack on cyl #1 failed. Borrowed another one and placed it on cyl# 1 and turned the boost down a bit. No further problems. I just don't understand how additional boost could affect a coil pack. I can see that chipping might, and since the donor car was not chipped perhaps the first borrowed coil pack was marginal and failed when placed under more stress on my chipped car, but I have no proof. Wish I understood more about this. Thanks for your input.

Cruzad3r

thank you

TTschwing

Possibly a bad plug putting more strain on that particular pak? I'd look at them and check the gap...

Also, don't rule out the harness until you look at it. the insulation breaks are usually very obvious. A short there "could" take out the pak..

Good luck!

J. Patterson

Possibly. Chris Smith also asked about the age of my plugs. They are 35000 miles old. I had been accepting the Audi recommended 40000 mile interval. I had been fine with no issues till now. Since I experienced this I realize that components under higher than normal stress need more frequent than normal replacement. What has your experience been as to an appropriate plug replacement interval with a chipped car?
Thanks as always for this advice.

TTschwing

I'll bet your gaps are .040 or greater. Puts a lot of strain on the pak to fire an old plug with large gaps. Personally I'd shoot for 20K intervals, especially chipped and tracked. Here's a set of IK22's (one range cooler) originaly gapped to .032 (Stock spec) at 22K.....They still ran great, but Iridiums are a little more efficient.

<img src="http://images22.fotki.com/v817/photos/7/7305/776256/IMG_1253-vi.jpg">

Russ Scott

sorry, pics were deleted :-( But I'll try to answer any questions...

tvdqi

Hi - I'm new to this forum but not new to Audi World. I was reading through here because I'm interested in a TT, and I noticed your post.

As cylinder pressure goes up the voltage required to bridge the gap at the sparkplug goes up - if the increased boost on the track raised the cylinder pressure high enough the coilpack could arc internally, killing it instantly. Once the coilpack arcs internally the high voltage will continue to use the path of least resistance, namely the coilpack, i.e., it's toast.

This is one reason why some manufacturers warn that electronic ignitions not be operated without a load on the secondary (high-tension) circuit.

Monitoring spark voltage and duration is actually used by some ECU's to monitor each cylinder's operating condition. I'm pretty sure Mazda is using this on some of their new, high-performance engines.

Turning down the boost of course lowers the cylinder pressure - I'd bet that's why you didn't have any further problems.

Bob Johnson
(yes, I am an electronics geek.....sorry)
Claremont, CA

J. Patterson

Thanks Bob! Great info.