2010 A3 1.6 SE Technik BSE Engine P0304 - Help needed diagnosing this misfire - Tried all the usual suspect parts

[Crasher]

No they are plug and play, you are narrowing this down to an air leak on that cylinder, pop the inlet manifold off and check the seals.

[campbell1987]

No they are plug and play, you are narrowing this down to an air leak on that cylinder, pop the inlet manifold off and check the seals.

Have tried the inlet manifold from new engine and same thing. Guessin a smoke test might help here... i can make a sm9ke tester with old soldering iron just unsure how to test it all properly. Like does each cylinder need to be at TDC to check for leaks... have an idea what to do just some guidance here will help a lot.

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[Crasher]

No, you need to generate a huge amount of non toxic smoke under around 0.5Bar of pressure so your idea would not produce enough of the right kind of smoke. Pressuring the intake after the AMM and if possible with a smoke generator is definitely a good idea, if what you say is all correct I am of the opinion you are looking for an air leak on number 4. Have you checked the brake servo pipe and its vacuum sensor for leaks as these play up and can get messed around with?