I'll start off with what I've already done.

1. Boost leak test, passed until the tester blew off
2. rebuilt throttle body(was leaking with first Boost leak test
3. replaced tps
4. Replaced map
5. Got injectors cleaned and flow tested
6. Changed COP setup
7. Changed plugs and gapped them at .018 and .020
8. Went a step colder in plugs

None of this has helped or resolved my issue. I'm beyond stumped

My next thing I'm doing is replacing vacuum lines from bsc to turbo, wastegate and intake.

Now as for my issue. It's quite frustrating. My car will cut out/misfire at wot. Recently found out I was spiking at 35lbs of boost. It's not always at wot unfortunately when it cuts out. It'll also happen if I'm cruising in 6th gear and I give it slight throttle to pass someone (roughly at 65/70 mph) my blow off valve flutter and then car sounds like a Subaru. Once that happens It'll take roughly a minute to minute and half to run back to normal.

Also during the cutting out/misfiring Subaru sound, my fuel trims are pegged rich 10.0 on my wideband

And other input would be appreciated. I'm at a loss here of what is the issue. It was running amazing beginning of summer, and once the really high temperatures came it started acting up.

Mod list if necessary

Fully built block/head
71hta
E85
1100cc injectors
Wally 255
synapses bov
Vrsf fmic
Injen ic pipes
Speed density
Factory wastegate
Grimspeed ebc
Balance shaft delete
Kiggly hla

 

Do you throw a P0300 code?

 

No codes been thrown. My cel light has never worked ever since I bought the car. I do scan it every so often. Ive scanned it 3 times ever since this issue has started and every time 0 codes found.

 

NVM reading comp fail.

Sounds like maybe a tune issue, what are your afr’s like?
You said fuel trims pegged at 10? Did you mean afr or LTFT?
Running super rich can cause a misfire. If you're over boosting what you were tuned for you could be hitting a region of your fuel map that was untuned and set to be super rich just in case. Have you discussed your issues with your tuner?

 

When just cruising and everything is normal. My afr sit at 14.7 plus/minus a few points or 2. It only pegs 10.0 when it starts misfiring, and peaks at 35psi or more. I'm tuned for about 28lbs. The car ran perfectly and pulled like a rapped ape for several months after getting fully tuned. Just out of the blue the cutting out/misfiring started

 

Have you checked the ends of your cop system, where there's either a metal boot sucket type that makes contact with sparkplug or little springs. Make sure there's no carbon deposits in there or corrosion from poor contact. Considering the pig rich your getting there's a good chance that one sparkplug is not firing. Or not enough voltage going through at random times. Or possibly problem with fuel map tune. Have to remember also when your car starts misfiring your ecu if stock, will start pulling time and riching up a lot. Also maybe there's too much difference between the main fuel map and the secondary map or timing maps.

 

Spiking 7lbs over what you are tuned for is not good. There has to be a reason why that is happening. Check for electrical gremlins with your COP system, as well as cracks in the boots going over the sparkplugs. Could a failing cam sensor (once it sees heat) cause such issues? You replaced the MAP sensor with a known good one? Check the wires going to the MAP sensor connector. The cruising issues remind me of when I had a bad MAP sensor. It seems you addressed the common things, just double check to make sure you didn't miss anything.

 

This may sound ignorant or trivial, but could it be bad gas?

 

It's actually a little counter intuitive but a miss-fire will usually read lean. The sensor is looking for oxygen, not fuel (O2 Sensor) so when you miss fire there is extra unburnt oxygen in the stream and the sensor picks that up as a lean condition.

 

Yes I replaced map with a brand new map. And I swapped out cop setup with a brand new setup as well. I'm curious is it's my wastegate going bad? All sensors are a year old new oem. I still have my original cam sensor I could see if that does anything different, but I don't think a new sensor would go bad so fast, but could happen.