Unusual spark plug service interval.

[boostjunkie]

Ever since I've had my car I can remember changing the spark plugs fairly frequently. When I was having the car inspected I noticed that the engine would hesitate and bog pretty bad under boost. I replaced the plugs (at the time boschs - the suck!!) with ngks one heat range colder. It solved the hesitation problem completely and then I had that alternator servicing which helped with any hesitation afterwards. I started notcing the same symptoms again maybe 15,000miles later, changed the plugs, and fixed the problem. Again, the symptom of hesitation, bogging, and lack of power surfaced, so I changed the plugs and wires another 10,000miles later. This past winter I came to you guys with those problems of the a/f sort. After fixing that problem, along with a MAP sensor problem, I noticed the same symptoms of hesitation, where I couldn't go WOT without the symptoms manifesting themselves. A roll on the throttle would keep the problem from surfacing. Finally, it got so bad that I couldn't really go full boost.

Well, I decided to change the plugs again, figuring it was for the better since I had those a/f problems and was probably running lean. Sure enough, the plugs showed signs of lean running and the replacement fixed the problem when I can boost WOT at any rpm (although my clutch would disagree with this).

It's been about 10,000miles since the last replacement.

Is this service interval normal? What would cause the plugs to go bad before the specified 30,000 mile interval?

Thanks, yet again

[evolutionmovement]

What do the plugs look like when you pull them?

Steve

[boostjunkie]

This time they showed the whiteish tinge, which I was expecting considering the car was run with those crazy a/f ratios. However, all the other times the plugs didn't show any unusual wear/sooting that would lead me to believe that they were bad.

[kyledooley]

Whitish crap on the plugs can sometimes mean you're burning coolant. Do you lose coolant at all, or do you puff any white smoke when you get on it? Keep an eye on that.

Secondly, the main reason you're having to change your plugs so often is that you're using colder plugs. They foul much more quickly.

The reason you use colder plugs is that the tip doesn't retain as much heat. (Hence the term colder). Of course we use them because they reduce detonation but the drawback of doing that is they foul more quickly (because they don't burn off the carbon deposits and other gunk as easily.

The initial problem would have been solved by just changing the plugs to the stock range. I would just go back to the stock range the next time you change them and see how much longer they last.

Kyle

[DOA]

Or even better swap the plugs every time you change the oil since proper service intervals tend to be way too long anyway (and I did think it was every 6000 miles anyway).

[boostjunkie]

Hmmmm, I guess I'll just change them more frequently. BTW, I'm using the stock range now.

[kyledooley]

So out of curiosity, how long have you been back to the stock heat range? Do they last any longer than you were describing above?

Kyle