I have one of the earliest examples of the 30v. The car is coming up on 50K miles, and I decided to change the plugs myself, since the nearest Audi dealer is a good drive away. I received NGK plugs with the following markings:<br>101000035HJ<br>R5<br>BKR6EKUB<p>The plugs I got in the mail had 2 prongs, which extended about 1/8 of an inch. I went ahead and began the process of replacing the plugs. When I took out the stock plugs, I noticed that they had 3 prongs instead of 2. I confirmed with the dealer that they were the correct plugs, and assumed Audi must have made a running change. I went ahead and replaced the plugs.<p>All was fine for about 2 or 3 weeks. Then I had a problem. The car sat overnight, after running perfectly the night prior. I woke up the next morning in 5 degree weather and tried to start the car. It cranked and cranked, but wouldn't catch. I let the car sit a few days, as I knew the weather would warm up, figuring it might be some water in the fuel line wreeking havoc. Still wouldn't start. <p>I pulled a plug and found that it was fouled. They were covered with soft black deposits. I was baffled. Unfortunately, I had thrown away the old plugs. I again ordered new plugs, but specified the 3 prong plugs (which was what was in the car in the first place).<p>I carefully examined the 3 prong plugs versus the 2 prong, and found that there were other differences. The 3 prong plug's prongs actually extended further than the 2 prongs plugs. Quite a bit actually, about an 1/8" longer. The prongs AND the electrode were longer on the 3 prong.<p>So, I popped the new 3 prong plugs back in the car. It started right up, and has been running fine for the last few days.<p>Does anyone have any light to shed on this? Unfortunately, I didn't get the whole number for the 3 prong plugs, as I stuck them back in the car rather quickly. <p>One thing I did notice was that there was black muck on the tops of the pistons, as well as on the plugs I took out. I assume this is from the plugs that potentially weren't creating the right burn, combined with my cranking the engine without getting combustion? I ran the car at 4000 to 5000 rpm on the freeway for about an hour in order to try an burn that crud off. I will also try and find a Chevron station to get some Techron, which couldn't hurt.<p>Any further advice? I assume that since the "buildup" on the pistons only took about 200 to 300 miles to accumulate, it would disappear rather easily? Is this a good assumption? Is there anything else I should look out for? I guess I'll pull a plug in a couple of weeks to make sure all is well, but in the meantime, I'd love to hear some thoughts if someone knows what may have happened. The dealer STILL says the 2 prongs are the plug that Audi specs for the car. This also baffles me, as the stock plugs I pulled were the 3 prongs. What gives??????? You can tell I am confused.

Robert, interesting experience. Couple of thoughts.<p>1) I find it hard to believe that if a car was running perfectly for several days (incl. starting fine), that a cold snap would cause it to fail to fire at all due to spark plugs. I feel something else caused this, which is probably something for the dealer to look at via a code download.<p>2) Re the deposits: I tend to think that these didn't have a chance to bake in; your "italian tueup" probably blew them out (to the "Politically Correct" police - I'm half Sicilian descent, so stay off my case!). <p>Re Techron: you can get this in many auto parts stores.<p>Re plug check: I would be careful about reinstalling a plug that was removed, since you have crushed the little washer at the end of the plug threads. To me, this should be replaced if you intend to reuse the ame plug, but don't know where you get them! (I am assuming that the Audi plugs actually use them; my old Coupe Quattro did, but don't know about the 30V). Also, recommend use of a torque wrench and tighten plugs to factory spec (don't have the number, unfortunately). I have always used a antie-seize copper compound on plugs as well; this has been on old Coupe Quattro plus my Porsche 993.

Ray,<p>Thanks for the feedback. Yes, the plugs came with the collapsible washers. I guess I could buy another plug if I couldn't find the washer. I didn't use a torque wrench, but definitely didn't overtighten. I hand tightened, then added about a turn.<p>I'll look for the Techron at the parts store.<p>Regarding the weather, if the plugs were the wrong kind, and crap was building up because of it...the extreme cold start (very rich) may have just pushed it over the edge?

I finally decided to call the dealer, and after lecturing me on how I could have voided my warranty by changing the plugs, they told me that they had 5 or 6 other 30v's do the SAME EXACT THING on the VERY SAME MORNING!!! Plugs were fouled in each case. According to the dealer, if the car starts and only runs for a few seconds then dies (which is exactly what happened with my 30v), the plugs often get fouled. This is weird.

From your follow-on disacussion with the dealer, I suppose it could. I still have a hard time thinking that a single start could foul them that badly, eps. with these newer high energy ignition systems and lean-running engines to meet gummint emissiion standards.<br>

I am curious. Are the plugs changed at 30k or 50k miles? I had my car services in November for the 30 k and had a slight WARM hesitation at progressively decreasing engine speeds. Initially it was at 2800 RPM and has moved down to 1100 RPM over 2000 miles.<p>Could this problem be common? I amthinking the gap was insufficient, say by a fraction of a thousandth? This might explain the slow progression to lower RPM. It would explain the rapid fouling.<p>BTW, did you clean out the plug recesses before removing the plugs? There are valve cover gaskets around the plug holes. Oil might be the problem.<p>Good luck in restoring the lovely 30v power.<p>Keith