i have a large street port 89 tii fc rx7 w a borgwarner s360 turbo and 750 primary and 2000 secondary injectors, banzai racing s5 harness adapter and power fc. hitting boost around 4-4.5k rpm it was fine i didn’t have any stutter problems or anything. and one day it just started getting too rich (10 afr) in that area without any tuning involved, just out of the blue. and when you press the gas it’ll misfire or just cut like no power no noise but if you wait it out it’ll clear itself out. can’t seem to find what my issue is because when i first built it last year around this time it was boosting fine with no issues. doesnt matter how much i tune it, it’ll clear itself up during tuning and then the problem will always come back. any ideas on what could be the problem?

 

Was it out of the blue or was it because the weather changed? When did this start happening?

 

it was out of the blue. i tuned it again and it went away while tuning but came back. i recently had it tuned no symptoms day of and now around 4-4.5k rpm it misfires and runs 10.0 afr until it clears it’s self out while my foot is to the floor

 

What injectors and fuel pump? What change to the tune did you make for it to go away? What does the wideband say just before it happens?

 

Read your plugs ? How many miles on them? weak spark?

 

750 primary and 2000 secondary. walbro 450 for the fuel pump. the wideband will get richer as boost increases and just stays at 10.0 afr as it builds boost. the car will lose power and cut not making any noise with my foot on the pedal but if i let go it’ll just return to normal. but when that cut happens i’m pretty sure the injectors are still firing because i can smell fuel

 

haven’t pulled my plugs yet to see but it has 11k miles on them. i’m using all 9 plat plugs (bur9eqp) maybe it’s time to change? idk the stuttering/misfire power cutting happened out of no where

 

11,000mi on a set of plugs is really impressive. No idea what the "normal" interval is for the platinums. Before recommending anything else, change those and report back. According to what your wideband is saying, there's too much fuel. Whether its simply not being burned or its actually dumping is the next fork in the road. Replace the plugs before pulling any more fuel to rule out the lack of spark causing an over rich condition. Depending on what that does will determine the next move