With $140k of net profit allocated to you, the amount that you are eligible to contribute to the solo 401(k) is not about $44k unless your solo 401(k) permits after tax contributions. Without the ability to make after tax contributions and having already made the maximum elective deferral to the plan at the W-2 employer, your own contribution to the solo 401(k) is limited to only the maximum permissible employer contribution, about $26k.
TurboTax's Maximize function for a individual 401(k) contribution does not support the case where elective deferrals or Roth contributions are also made at a different employer. Since you made the maximum elective deferral at your W-2 employer, you need to cause TurboTax to calculate only the permissible employer contribution by using the Maximize function for either a SEP contribution or a Keogh Profit Sharing contribution for your contribution. You would still use the individual 401(k) Maximize function to determine your wife's maximum total contribution, assuming that she has not made any elective deferrals to another employer's plan.
