Hi
I suspect my evo may be leaning out on E85. the car is fine to drive at low revs but once i get to full boost and higher revs around 5k or so it starts to get little backfires and shudders and loss of power. It happens worse in the cold so i suspect the colder air is causing this to happen.

Im running 450 hp 28 psi with 1060cc injectors

 

Colder air won't make that big of a difference. Do you have an AFR gauge? It sounds more like your fuel pump is starting give up...

 

You really need a gauge to monitor if it's leaning out or not. Leaning out some on E85 probably wouldn't cause what you're experiencing though. You might be developing a misfire and need to change your plugs. I would check that out.

 

I never thought about the plugs but would the cold weather effect them? No i dont have one but Ill most likely invest in one soon

 

Try plugs first. Totally skipped my mind lol. If you have an Evo 8, get ngk BPR7ES and gep them to .020". If you have a 9, get the OEM plugs, and gap them to .020"...

 

Im in Australia and have a 7 so what would be the best plugs with the E85 and high boost?

 

I want to say they take the same BPR7ES gapped to .020". But I'm not 100% sure. Def still gap to .020"