[s-cars] Dodging the bullet; a short story -

[djdawson2 at aol.com]

Mike,
Over the course of 10k miles, I lost many of the Bosch F5DPOR plugs.  I'm not sure why it was happening, although a temporary lean condition would certainly accelerate the process.  I was at the point where I was carrying a bag full of plugs for the failures.  Lean conditions were not the root cause of my problems, as I was running the same basic tuning that I had always been running... and was still losing plugs left and right, and had never lost even one in the past.
 
Around the time I posted the "short story" I had lost the entire ceramic post while traveling in California.  This caused an extreme amount of noise, one that I was certain was an actual mechanical failure, not a plug failure.  I had gone to the extent of finding a truck and trailer to bring the car back to Denver from California.  It was while I was waiting for the truck/trailer being delivered to me that I decided to pull the plugs... where I found the one missing its entire post and insulator.  Replacing the plug made the engine run right, but the noise persisted, and then suddenly was gone.  Needless to say, the shrapnel finally passed out of the cylinder.  The car has run fine ever since.
 
I've had quite a few Audis over the years, and I had never had this type of plug failure before... although I had heard of it.  Suddenly, it was happening to me every 1000-2000 miles.
 
I have not yet assessed what damage took place inside the combustion chamber, since I have not removed the head since that incident... I am certainly curious to see, however.
 
My conclusions:
 
NO MORE BOSCH SPARK PLUGS!  I don't know if it was a bad batch or what... but I had at least a half dozen failed plugs in a very short timespan.  Some lost electrodes, some of them had the ceramic post begin to spin freely inside of the metal housing and leaking compression, and others just stopped firing.  Most recently, I removed a nearly brand new set of Bosch plugs from an '82 Coupe GT (I believe it was putting out about 45 wheel horsepower), and one of those plugs was also literally falling apart.
 
Since then, I have switched to NGK spark plugs.  I am currently running the BKR7EIX Iridium plug.  They have now been in the car for just over 9000 miles.  Not real long, but they have worked great so far.  Considering my Bosch plugs were failing SO frequently, it has been a relief not to have to pull out the tools every 1000 or so miles on the side of the road.
 
NGK offers 3 different grades of plugs for the AAN engine.  Go here:
 
http://www.ngksparkplugs.com/apps/car_truck_suv/default.asp?nav=60000&country=
 
I bought a set of the Iridium plugs (in use now) and a set of the "standard" V-groove plugs.  I haven't tried the V plugs yet, but would like to see how they work.
 
The Iridium plugs are priced similar to the Bosch plugs... the V-groove plugs were under $2 each, IIRC.
 
I'd suggest giving them a try... maybe even be the list guinea pig for the V-groove plugs.  After all, at less than $10 for a set, it would certainly be worth a try.
 
Turbo damage...
 
I had wondered the same thing, thinking a turbine blade would have likely suffered some damage from passing the electrode and ceramic post.  Fortunately, this was not the case.  Just Monday of this week, I removed the turbo and header from my car to re-weld my header from an encounter with a speedbump.  The turbine wheel looked completely undamaged.
 
Anyway... good luck,
 
Dave
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