"Unless" in certain conditionals.

Does anyone here find a problem with the use of "unless" below?

She wouldn't have come unless I had asked her to, and I didn't.

You wouldn't have passed the exam unless I had helped you.

I know we can use "except if" in the first example and "if I hadn't" in the second example, but what about "unless I had"?

NB I get mixed reactions from native speakers on this.

"Except if" would not be correct for either example. It sounds extremely awkward to these American ears.

"Unless I had" is correct for both.

I am American as well and I agree with Michael about the first sentence, but I think "unless I had" sounds off in the case of the second sentence. I would say "if I hadn't" instead.

"Except if" would not be correct for either example.

There's no problem with "except if" in the first sentence.

<but I think "unless I had" sounds off in the case of the second sentence. I would say "if I hadn't" instead.>

How about here? Examples from Americans.

1. "Because I wouldn't feel that I was speaking to the intelligence community unless I had good reason to do so."

2. " I got support from nowhere except the gay community. The gay community taught me how to survive HIV disease, and I don't think I'd be here today unless I hadn't reached out to them and built a bridge."

3. Remember the great high school cross-country star?, he wrote, I did it only to prove myself to Dad, running until dizzy, stopping only to vomit by the side of the road. It got to the point that I knew I hadn't run well unless I had thrown up.

Well, number two doesn't make sense. It should be "if I hadn't" rather than "unless I hadn't".

I suppose the others are okay.

<<<Well, number two doesn't make sense. It should be "if I hadn't" rather than "unless I hadn't". >>>>

Why?

How about: "If'n i didnt' ask her..."