Which one is correct?
I was wondering if it {was|is} not too late to ask if you could give me ...
Which one is correct?
I was wondering if it {was|is} not too late to ask if you could give me ...
The first one makes more sense grammatically, but "I was wondering" is often used as a substitute for "Excuse me, please," - so, people pretty much say anything after it. (US):
"I was wondering/Excuse me, please...
... is this the line for the ladies' room?
... has Elvis left the building?
... was that you, kicking me under the table?
... could I have a look at that?
Both are commonly used.
Wondering if it is too late is straightforward - "is too late" is the present tense, and it's being used to describe a situation in the present, so everything is as you'd expect.
Wondering if it was too late is harder to explain. The most succinct reasoning is on this page from the British Council, which simply states that the past tense can be used "for politeness". This question and answer go into it in more detail.
But the sentence you have is more complex than that. I think you might be asking whether the two tenses have to agree: whether the bold words in "I was wondering if it was too late" have to match.
If so, the answer is no. When you're using the past tense in the normal way, there's no need for them to match - "I am wondering if it was raining yesterday" is clearly perfectly fine - and so there's no reason why they'd have to match when the past tense is being used for politeness alone.
By the way, I was wondering if it was not too late is quite formal and stilted. You'd normally contract was not to wasn't (and the same with isn't). It would also be perfectly common to say I was wondering if it was too late or I was wondering if it's too late, hoping for the answer "no".