Buick Grand national 3.8 Turbo breaking up on higher boost

[mrybnik]

I have an 1987 Buick Grand national with ms3x. I am running sequential fuel injection. The car is breaking up/ back firing when I floor it and it goes in to boost. It runs fine when I plug my original computer back in. I attached a msq and a data log. Any suggestions would be greatly appreciated.

[Matt Cramer]

First, set the timing to fixed angle and confirm the timing is correct across the entire rev range by free revving the engine. If not, adjust the spark latency.

[piledriver]

What coils? may need to play with the dwell too.
Can't recall if the devs added a dwell tweaking ability at high load... Not all coils can deal with it anyway.

[Lxmodguy]

Did you ever fix this? What coils are you running? Are you using the Casper adapter from the xfi or did you wire the motor yourself?

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