I have a problem my car is missfiring at around 4psi. Its just around the 4000rpm area then it opens and pulls hard to redline. I will attach the dyno graph. The previous owner told me it was because of the cams opening, also at that same point the afr gets a little lean but I assume that is caused by the missfire.


My setup is
B18b1 engine
Cp 9.0-1 pistons Eagle Rods Acl Bearings
Crower stage 3 cams
Supertech Spring and Retainers
K20 rsx coils
Ngk R5671A-8 plugs gapped to 0.17
Haltech sprint 500

 

If the afr is lean at the misfire it would be rich not lean... If it isnt firing it isnt burning fuel..
take it to a better tuner

 

Had a similar issue, basically bad tuner new tuner fixed the issue. First tuner didnt do a good job there was a lean spot in the map and needed more fuel

 

I already add fuel in that load and it didnt do much. Already checked spark plugs, coils,that the timing didnt drift, fuel compensations.

 

Why are you running such a cold plug? That's not even remotely necessary unless in a Circuit condition. Running too cold can actually cause more issues than it solves. Have you tried a 7 heat range yet? I'd look into that.

 

havent tried them yet, will check them for sure