Popping noise from intake on start up

[T Lash]

I bought this car from my girlfriend. Long story. When I bought it the engine had been pulled due to a blown engine. The mechanic that tore it down left the state due to a family emergency. It took me a while to find a mechanic that would put the puzzle back together. I bought a engine an turbo from Mazda. From day one the engine makes a popping noise for a few seconds then stops. I could smell exhaust fumes. It took me a while to find where it was coming from. I took the intake off and had it resurfaced. I put it back together and I still have the same issue. I screwed up and did not check the head with a strait edge before I re assembled it.

On disassembly I found the blow by on cylinder 4.

Has anyone had this issue? What was the fix?

[MSMS3]

If the head is warped, get it resurfaced. But you could have some other issue. Why do you say you have “blow by” on cylinder 4?

If it’s a loss of compression, it could be a valve not seating or burned, an injector seal, for instance. Is the engine properly timed?

[Jeff23spl]

please define poping noise ?

the intake isn't likely to warp much as head and intake is aluminium. But head to bloc is another story. rebuilding an engine without surfacing the head to bloc surface is likely to make problems unless is carefully checked....But none of those issue would create a noise at start that disappear later...

you can do a air path leak test, there is plenty of threads about it. IT is likely to shift your fuel trim and create a cell if it goes above or below 25% correction