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Discussion Starter #1
Hello Fellow WRX enthusiasts! I am new to the community and was hoping to find some insight from the people who buy these cars because they Love to drive them. I purchased my dream car about 3 years ago. A mostly stock. Silver 02 WRX Turbo! Big ass Blast Pipe so you can hear the engine purr, tinted windows, sick stereo, sub woofer, and bike racks.Totally stacked! Boom Loving It! Its in great shape for its age, and I plan on keeping it that way. Fast forward 3 years later and I have aftermarket rims, fancy new Halo Bugeyes, refurbed rear diff complete with left axle and main drive train, oops! a couple of new A.C. pumps, new clutch, fuel filter, dozens of oil changes with the OEM Filter, and A bum coil that got replaced with a used one from the local Subaru Shop, not the dealer.

Now I have two more misfire codes popping on the dash, 0301 and 0304. Leading me to believe its time to replace all the coils, Plugs and wires. My question to you all is, which parts do I purchase to "upgrade" my baby without breaking the bank? My Old man is a Subaru mechanic from the pre 2000 era and was a college Automotives Professor after that for 20 years, and while his knowledge is great, he does not necessarily keep up with the times anymore especially as far as tuning a 02 WRX at high altitude lets say. I reside around 5000 ft or more with frequent trips to even higher elevations. He recommended I buy the NGK ignition coils, the H4 I believe. Is there something better or are these the way to go? And The plugs? NGK Irridium?

I would appreciate any feedback you all may have, Thanks!
 

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I recommend you properly troubleshoot the issue before throwing money at the problem.

As your father could no doubt point out, if it is indeed the coils then the CELs should follow those parts. That is, if you transfer the coils to another cylinder then the CEL should "follow" an ostensibly bad coil.

Note that the coils are not wear items. The spark plugs certainly are, and it is conceivable that they'd cause misfire CELs if past their useful lifetime. However, there are several other potential causes for your CELs.

We had an extensive "if you have a misfire code, read this" thread at one point. I recommend finding it and following that writeup to the letter.

Spark plugs combine the technology of a flint with that of a battery and toilet. They're one of the few reminders of how primitive even a modern engine actually is. You can use iridium plugs if you wish; I do because they're not more expensive and they may last a little longer. Other than longevity I see little reason to mess with plugs on a motor that is operating correctly.
 

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Discussion Starter #3
Thank you for your swift response. I agree with you in that there is no need to throw money at problems that don't exist. I would also agree that I could run said diagnostics and figure out which coil or plugs are bad, etc. However, while my father may be a mechanical expert, I am not, and he lives 3 hours away. His diagnostic equipment isn't as awesome as it was when he worked on campus, and traveling in square states this time of year can be deadly. I could probably manage swapping out spark plugs and coils myself, but lack enough patience or free time to swap things around just to see if the misfire followed. My time is worth enough to me to just replace all parts in question and not have to worry about it again for several years. Especially if I can get even a mild performance upgrade. I have no service records for the car previous to my own other than the solemn oath by the previous 2 owners that all the regularly scheduled maintenance was performed. I figure the spark plugs need changed for sure, and the coils having already had problems once and now twice are not so expensive that it wouldn't be worth it for me to swap them out while I have the car torn apart. So my question really was, Can I get performance upgrade while doing the maintenance work by purchasing better plugs/coils? FYI, not looking to spend STI level cash. Just want the car running good, and reliably. more pep would be a plus. Thanks!
 

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You will not gain any performance or efficiency on aftermarket plugs and coils on an otherwise stock vehicle.

This isn't a D-series Honda. There are no spark plug wires.

Replace the plugs with OEM replacements, swap the coils between cylinders 1 and 2 and cylinders 3 and 4, reset the learning and see if the misfires go away. If not, use a datalogger to determine the fuel trim at idle and cruise. Misfires can be caused by bad spark OR improper fueling. Cylinders 1 and 4 are on separate heads so it is unlikely to be the fuel rail. Good luck and I agree with Spiros... don't just throw money at the problem.
 
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