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I have a new build street/strip car and am having an issue I just can't seem to find. Car is going full rich after we've run it hard for a few hours.
I ran it on a dyno Friday, things went to plan until the end of the second hour, then the car gets to 4k rpm and goes full rich, AFR 10, loses rpm. Went back to an earlier tune that was fine on the dyno, it now also goes rich at 4k and loses RPM. Spent an hour adjusting fuel, changing plugs, checking connections, and never solved it. Took it home, reflashed firmware and it seemed to be fine.
Saturday I run it five passes at the track tuning. No symptoms other than the idle is horrible when the motor has made several passes, I assume this is a tuning issue.
Sunday. Ran 3 passes with no issue other than tweaking the tune. Run 4, the car is idling horrible up to the line. AFR gauge is reading 10. Pull into burnout box and the same thing, full rich and no power. Pull up to the line and drive down the track, the same thing 10 all the way down. I get to the return road and the AFR starts moving again.
Some items of note: Stock long block LS 6L, BTR stg 4 turbo cam, springs, Bosch 210 injectors just cleaned and flowed, three Walbro 450 pumps, AN12 fuel line, 88mm Borg turbo, E85 w/flex. Same Goldbox from my other car I ran last year. Same injectors, same regulator, same coils, same firmware, and started with the tune from my other car. At 4psi it is 500whp. Aem Uego Wideband
During the run down the track at partial throttle, EGO correction shows 99.7 AFR Target was 13, actual was 10.4 Notice the AFR is flatlined at 10.4 all the way across like its the bottom limit of the gauge. If I understand correctly, the ECU should have been commanding 25% less fuel. E75 from the flex sensor. i can send the log and tune, it won't let me attach them. Any thoughts?
And a video of the launch as a reward if you read this far!
Problem seems to be gone. Changed dwell from 4 to 3 and have not been able to replicate. Hot lapped 3 passes this weekend with no issue. D585 heatsink coils were being used.
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MS3 Fueling Issue when hot 
