Tuned on Tephra v3 (e85) with walbro 450 and ID1300s. gtx3576r, built 2.05L, gsc s2 cams.

I have been having weird intermit fuel delivery issues. AFRs look good at WOT and idle. However, randomly it would just fuel cut. Well not randomly, it's happened during pulls.

It's happened last time when I tried to launch the car. I would go into 2nd and fuel cut. I thought maybe I just screwed up getting into gear but I am pretty positive it was the car. Then after I pulled over, I restarted the car and it was acting strange. It would hesitate and go lean when I would get into boost. It did it the entire time I drove home for about 10 minutes. I then got home and shut the car off for about 20 minutes, looked over everything and then went for a drive again and the car was fine. No issues since. I also had no CEL codes. However, this last time I had maybe a 1/4 tank of E85 so it could of been just fuel starvation (obviously doing that under 1/2 a tank was probably a bad idea). What I didn't understand is why it was acting like that after the launch, like the fuel pump was dying.

There was another time, this is the first time it happened, I was doing a pull and it did it going into 3rd (no launch, plenty of fuel, 30 roll). We thought it was just related to spark blow out. I changed the plugs (and got a tune update that's suppose to help with spark blowout) and it didn't do it again until I tried to launch.

Also if I like "miss" a gear, say going from 1-2 and mistiming the clutch, it will then do fuel cut if I try to go over 5500. Like some kinda limp mode, its happened 3x. It did this at the drag strip (no launch). I screwed up going into 2nd, it grinded and then wouldn't let me get back into it (at 5500 rpm would fuel cut). I went back out there like 5 minutes later and it was fine but then when I hit 4th it did fuel cut again (no messing up shifting). I went back out there like 20 minutes later and it was fine. Not sure if the limp mode thing just needed the car to sit longer...

I know this is just me kinda rambling. I am going to get a fuel rail put on soon and test the fuel pressure. My tuner told me to start with the fuel pump. I don't want to just start replacing stuff if nothing is wrong. Any feedback or suggestions I am open to. Thank you!

 

Sometimes people confuse fuel cut with spark plugs.

 

I would put a 10 bar fuel pressure sensor on the rail and monitor fuel pressure with a gauge in cabin. Your symptoms are similar to a friend of mine who received a bad fuel pump. Brand new 450 and it runs lean (18-19) even on idle.