My frustration is finally over!! I finally figured out why my car would studder and ocasionally misfire under boost. Apparently, my mechanic didn't gap the new plugs that he put in when I got my new (used) engine put in. I was thinking it was the coil packs all this time. I'm glad I didn't waste my money buying them. Anyway, since someone suggested to check the plugs, I said what the hell and bought some new ngk bkr6e v-power plugs to put in after I took the other ones out. I found out that the ones in the block had about a .035" gap. When I got the new plugs at the auto parts, their computer said that the gap should be .028" for a stock 1.8t. I thought it was supposed to be .032"? So I decided to do a little experiment and gap them to .025". The car is like night and day now. No misfires at all under boost, great smooth accelleration, and the characteristics of the engine have changed. Deceleration is way slower which allows for smoother shifts and I even get better gas mileage. So, I'm very happy now and wish I would have figured this out sooner.

 

Gap is .32" for stock cars and .28" for chipped. Audi undergapped the plugs for longevity, so by increasing the gap we burn better. But when you up the boost, you need to lower the gap to keep the spark from being snuffed out.

Also, I'd recommend copper plugs (BKR6E) for chipped applications. The copper dissapates heat faster than irridium and reduces pre-detonation. They go bad every 5k-8k so change them every other oil change. They're a lot cheaper though.

 

Yeah increase that gap a bit.

 

Why? The car is running great now. Also, Pulstar plugs are required to have a .025" gap, so I don't see why I can't do that with the NGK's. Plus, .025" isn't very much of a difference compared to .028".

 

Yeah, and .28 to .32 is only .04" but that tiny gap makes a world of difference. You were way overgapped before, now you're under.

 

Yeah, you have a point there. I've just heard of guys going down to .020", which is really extreme, to fix their boost problems on other forums. So, I didn't think .025" would be that big of a deal. I'll just leave it the way it is though and try out .028" next time and see what happens. I wonder why Pulstar plugs state that damage to the plug can occur if they're not gapped at .025" though.

 

actully you want ngk bkr7e they have a colder heat rateing gapped at .028

 

Yeah, I wanted to get those actually, but I couldn't find any auto part stores that have them, and I didn't feel like ordering them online. I'm ok with the 6e's though since the heat range is the same as stock at least.

 

.025 is about 22% less than .032 and about 11% less than .028. It's pretty significant.

 

The reason damage COULD occur is that in some engines, if you over gap you could have the piston hit the spark plug.