My tally for the first six chapters (might have missed some, and/or included non-lies)

Ch1:2(Emma) C2:1(Mr Perry) Ch3:0 Ch4:4(Emma) Ch5:1(Mrs Weston) Ch6:7(2Emma,5Elton)

Chapter one: The lies begin with our heroine herself, but the first is a compassionate lie. Emma wonders to herself "How was she to bear the change?" of becoming her fathers sole companion, and "could not but sigh over it and wish for impossible things" for half the afternoon, but when her father awakes and wishes for just the same impossible things:- "I cannot agree with you papa; you know I cannot."
The next, would be "Mr Knightley loves to find fault with me, you know - in a joke - it is all a joke. We always say what we like to one another."
Its a bit of a strain on my credulity to try to pass this one off as consideration for her father's feelings - its a triple-dyed lie. Mr Knightley has shown a wry sense of humour (e.g."Who cried the most?" ), but no relish in faulting Emma. He is obviously serious in his admonitions ("You are more likely to have done harm to yourself, than good to them, by interference" does not seem a joke) and rather than saying what they like to one another, Emma is willing to let it pass with a change of subject, and Mr Knightley shook his head at her rather than comment on the comfort she took in being proved in the right about Mr Weston.

Chapter two has no lies, that I can see, until we come to the wedding cake (I class "Ah! Poor Miss Taylor. She would be very glad to stay." more as a delusion than a lie, ditto the handsomeness of Mr Churchill's letter.)
Mr Perry's duplicity, in acknowledging that "wedding-cake might certainly disagree with many - perhaps with most people" and taking no precautions to prevent his little ones from ingesting this poison, is beyond belief (and what kind of person would go around insinuating children eat cake? Strange indeed.)

Chapter three has an outrageous falsehood about the Martins: "The friends from whom she had just parted, though a very good sort of people, must be doing her harm" - and Emma's basis for supposing this is that they are a family she "well knew by character, as renting a large farm of Mr Knightley, and residing in the parish of Donwell- very creditably she believed - she knew Mr Knightley thought highly of them". To form such a conclusion on such a body of evidence is something worse than snobbery. On the other hand, she does not communicate these dishonest intentions in words or behavior, so its thoughtcrime not lies.

Chapter four: The slander of the Martins gets personal when Emma discovers Mr Martin is unmarried. Emma has the hide to disclaim "A young farmer, whether on horseback or on foot , is the very last sort of person to raise my curiosity." in the midst of her interrogation of Harriet on the very subject.(I do like Harriet's stoutly truthful assurance "I am sure I shall not wish for the acquaintance of his wife")
On surveying him in the flesh, Emma notes to herself that "His appearance was very neat, and he looked like a sensible young man" and as soon as he has gone she abuses his "entire want of gentility...so very clownish", although her suggest model, Mr Elton, does not win her personal admiration- "there being a want of elegance of feature which she could not dispense with".
She also notes that "Mr Martin looked as if he did not know what manner was." which seems at least harsh, if not dishonest, from a woman who chose not to acknowledge Mr Martin's very respectful treatment of her (even if his pleasure in it was feigned), and his restraint in waiting until Miss Woodhouse snubbed him, before he addressed the lady to whom he was already introduced. He does not keep Emma waiting, (but that could owe as much Harriet's concern and his consideration for it, as his courtesy), and this earns abuse as his "awkward look and abrupt manner", unlike Mr Weston's "quickness, almost bluntness" which "everyone likes in him because there is so much good humour with it-but that would not do to be copied".
His ignorance of Gothic fiction is offered as proof of "his being coarse and illiterate" (there were critics at the time - for example, Walter Scott - who with equal dishonesty and injustice, saw the reading of Anne Radcliffe's novels as proof of coarseness and illiteracy.) The model gentlemen are given no such test to pass (and even Mr Knightley is not so genteel as to feel a need to read every book a lady recommends to him, as a priority - although I suspect Mr Martin of telling a couple of polite lies, here.)
I wonder if the real difference between the men Emma regards as gentlemen, and the one that she doesn't, is that they collect rather than pay rents. Two of her models are as much agriculturalists as Mr Martin. And while I can't class it as a lie, I wonder how Emma knows that Mr Elton was "without low connections,; at the same time not of any family that could fairly object to the doubtful birth of Harriet." and how it could have escaped her consideration that a clergyman might well have some scruples in marrying a girl whose parents could dispense with such a sacrament, even supposing his family did not.

Chapter five: Lies of omission may be worse than lies of commission, but they are also more plausibly deniable, and leave little textual evidence. Smooth Mrs Weston ends her argument with Mr Knightley "to conceal some favorite thoughts of her own".Mr Knightley might have been perceptive enough to catch her whole meaning, but changes the subject so we can't tell. I can't really accuse either of deliberate falsehood, or misrepresentation in what they say, and our narrator does not explicitly reveal any secret thoughts of Mr Knightley. The hypothetically "poor Mr Woodhouse" (this from poor Miss Taylor that was!), is not an attempt to deceive anyone.

Chapter Six: Mr Elton gets into the lying game from the first time he opens his mouth. "The attractions you have added are infinitely superior to what she received from nature." is not even a gallant lie. What principally struck him was that Emma had made Harriet "graceful and easy", and what principally strikes me about "So much super-added decision of character!" is the "Exactly so" that precedes it. Emma has accidentally de-spined them both!
She is not taken in by his praise of her art, however("You know nothing of drawing. Don't pretend to be in raptures about mine.") Isabella proves to be ahead of her time, seeing beauty in truth, and naming it "justice" but Emma is an artist of her era - an era where this portrayed Napoleon being lead over the Alps, sitting backwards, on a mule, in a grey greatcoat, suffering from altitude sickness. In his defence, that artist quoted his model "A resemblance? It isn't the exactness of the features, a wart on the nose which gives the resemblance. It is the character that dictates what must be painted...Nobody knows if the portraits of the great men resemble them, it is enough that their genius lives there.". The English cartoonists loved to remind their viewers of this, but they also subscribed to his Romantic (and mercantilist) philosophy, like Emma painting commissions that were "only too handsome - too flattering".
One particular fashionable trick at the time was to give a portrait large, cow-like eyes, like Napoleon (or possibly not at all like). Mrs Weston tells us that "Miss Smith has not those eyebrows and eyelashes" so maybe Emma has followed that convention, which is not exactly lying. Her response to Mr Knightley's accusation is, though. "'You have made her too tall, Emma,'...Emma knew that she had, but would not own it." If Emma is a parody of the Romantic artist in this chapter, then Mr Elton is a parody of the Romantic critic, disinterested only in the sense that his enthusiasm for his favorite is determined even before the art is produced, and any flaw evident in the work itself can be praised as the genius of its author. "'it gives one exactly the idea of such a height as Miss Smith's. Exactly so indeed!'...'Any other situation would have been much less in character...I never saw such a likeness.'".
Emma's insincere desire "not to give him such a troublesome office for the world" is more than matched by his studied compliments. "What a precious deposit!" has an almost oxymoronic crudity in one sense, and in another could imply he has been given a valuable down-payment to guarantee a future obligation will be kept. I suspect a naughty realist has been playing with his words.