Originally Posted by mwiener2
Take the car to someone who knows Subarus. You have an underlying problem that needs attention. Properly gaped iridiums don't spark any differently than the coppers he put in. Now you need to change your plugs in 20-30k miles.
I don't disagree with ya at all. I just know the car hadn't idled smoothly in a few years, heck maybe since we bought it in 05. I asked the local Subaru dealer religiously about it and they said it was "normal" for a boxer engine.
I never had a CEL until I had the 100K tune-up on the car. New timing belt, plugs etc... From that point, before I got the car home, up to 119K I had a random CEL for cyl 1, Local subaru dealer changed the plug again, that didn't help, they then changed the coil pack, that didn't help. They switched injectors 1 and 3 to see if it would follow it, it didn't. Then I think the CEL moved to cyl 2--memory is fading a bit. Then finally, the plug fouled out completely and I towed it to a local engine builder because it was missing so badly.
He had the car for a couple days and couldn't find anything wrong. He did did a leak-down test etc to make sure I had nothing seriously wrong with the engine and he said it passed with flying colors and was in exceptional condition for it's age. He finally called and said, I think I know how to fix it. He has a buddy from Chicago that specializes with Subarus, Mitsubishi's etc. His recommendation was to put Bosch copper plugs in it. His theory, the best I could understand, was that the car had a lot of miles on it and simply didn't burn as clean as it did when new and was running on the "rich" side according to him. I reluctantly said OK because I was so sick of the random CEL.
I picked the car up and it had never ran better or idled so smoothly. I couldn't even feel it idle. The car was quicker and felt stronger. The only drawback was that my gas mileage fell 2-3mpg's. Other than that, the car ran like a new one. I was so happy with it, I decided to buy the Cobb accessport. Car runs even better now, idles fine but has a weird "surge" when under a light load, like when pulling a small incline anywhere between 50-70mph and the rpms are between 2-3k. A/F ratio is 14.4 to 14.7ish during this time. I cleaned the MAF last night but it made no difference. Car does not use a drop of oil.
If I hadn't experienced the copper plugs, I would never have believed how much better the car behaves. But again, I'm not disagreeing about the NGK's just giving you my personal experience.