i need help- misfire only between 4800-5500

[MikeDombeck]

its not the plugs, maf, fuel, or ground to the packs........ the tuner said my car jumps ignition between those rpm's... if u look at my dyno sheet it stays steady making power untill that range then looks like it loses power, but right after that it jumps back up again.... fuel is around 11-12.3 the entire way... any suggestions, i am out of ideas.

[sonnyCA]

Check the coil packs for cracks...

What spark plugs do you have? And, at what gap?

How is your ground on your igniter?

[the converted]

What are you using for tuning? That's in the peak torque area so it should be richer there with a little less timing. If your running an afc, try just pulling a few degrees of timing at the distributor and see if that helps at all.

[MikeDombeck]

i think i found the issue, the ground to the coil packs had a butconnector in the wiring and one end just fell out, i retightened it and it still misfires but now runs really rich at that point instead of 12, its below 10... i think with a retune it should be better now... could a weak ground cause only a misfire at a certin rpm.. maybe it pulls more voltage and the weak connection caused a stumble?