Car is throwing Codes

[Hoonigan450r]

Hi my is car is a 06 wrx sti with around 73-74000 miles and its throwing P0304 cylinder 4 misfire from time to time. I just recently just upgraded to E85. Is this normal? Anyone know how to fix this before something bad happens?

 

[IGOTASTi]

[MENTION=9]HolyCrapItsFast[/MENTION] does.

 

[Spamby]

I'd say log it but [MENTION=9]HolyCrapItsFast[/MENTION] would be able to tell you what to log.
You can try swapping the coil packs around to see if the code follows the pack and determine if it's the coil pack.
#4 is a notorious cylinder. Maybe even a compression test while your swapping coil packs to see if that one has low compression.
What mods are done to the car?

 

[HolyCrapItsFast]

I'd say log it but @HolyCrapItsFast would be able to tell you what to log.
You can try swapping the coil packs around to see if the code follows the pack and determine if it's the coil pack.
#4 is a notorious cylinder. Maybe even a compression test while your swapping coil packs to see if that one has low compression.
What mods are done to the car?

^This... and/or the injectors

 

[Hoonigan450r]

Injector dynamics 1000cc injectors, injector dynamic side feed- top feed conversion, deaswerks 210 fuel pump (i could be wrong), cobb turboback exhaust system and cobb sf ram intake