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I'm getting code for misfire in cylinder 4. All 4 spark plugs were replaced less than 2 months ago.
This code was thrown as it was in the dyno getting a tune at the shop. The tech also said there was only 16 psi boost (which he said was not alot).
I took it to another shop to get it fixed and they suggested that it may be a vacuum leak.
Is this possible? Can a vacuum leak cause a misfire? It makes sense that there is not much boost...
 

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Its possibile if the leak is large enough causing a lean condition. What kind of mods and mileage do you have on the car? What boost levels do you normally see and expect?

If you took it to a shop to get fixed, are they fixing it? I think the best course of action would be to go about looking for any kind of air leak and vacuum leaks. I used to be a firm believer of smoke testing but now im going to recommend doing a boost leak test every time lol.
 

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Try swapping out coil packs and see if the misfire moves to that cylinder. Maybe the connector isn’t on fully?
 
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