That was a fast change of the intake. Given the loose hose and bolt, I suppose it wouldn't hurt to go around the engine lto make sure everything is as it should be.
Did you replace the valve cover? Our Astra had a poorly-designed PCV flapper which started leaking around 60k miles. That could cause misfires.
It wasn't easy for us to diagnose but here are some tips we used for c.2008 z18xer engines (GM stated they had revised the PCV around that time so yours might be different). Below are some tips we used, but of course the system could be different for the 2012 Cruze.
"Try to pull the dipstick out when the engine is running. Get someone to rev it to around 3k when you remove it. It should come out without to much bother. If it comes out and theres a vaccum then theres a good chance the membrane in the rocker covers gone and its causing a vaccum which is were your noise is coming from."
Video below for an Astra. The first 58 seconds shows how one might detect a bad membrane and how a new one behaves. The small rectangle hissing & oil cap removing difficulty are hints. Google translate of some of his comments: "symptoms of damaged pneumothorax: hissing sound as in the movie and sometimes strange knocking, knocking, uneven engine operation, oil burning, oil in the collector, suction of the oil filler cap"
Below, these guys sell replacement membranes, but I don't see anything listed for your car. We just purchased a new valve cover, but even with brute force, we couldn't disassemble the hardened plastic housing for the PCV (the video says to use heat and that it is easy to break).
vanos-bmw.com
Did you replace the valve cover? Our Astra had a poorly-designed PCV flapper which started leaking around 60k miles. That could cause misfires.
It wasn't easy for us to diagnose but here are some tips we used for c.2008 z18xer engines (GM stated they had revised the PCV around that time so yours might be different). Below are some tips we used, but of course the system could be different for the 2012 Cruze.
"Try to pull the dipstick out when the engine is running. Get someone to rev it to around 3k when you remove it. It should come out without to much bother. If it comes out and theres a vaccum then theres a good chance the membrane in the rocker covers gone and its causing a vaccum which is were your noise is coming from."
Video below for an Astra. The first 58 seconds shows how one might detect a bad membrane and how a new one behaves. The small rectangle hissing & oil cap removing difficulty are hints. Google translate of some of his comments: "symptoms of damaged pneumothorax: hissing sound as in the movie and sometimes strange knocking, knocking, uneven engine operation, oil burning, oil in the collector, suction of the oil filler cap"
Below, these guys sell replacement membranes, but I don't see anything listed for your car. We just purchased a new valve cover, but even with brute force, we couldn't disassemble the hardened plastic housing for the PCV (the video says to use heat and that it is easy to break).
Membrane Vauxhall Opel valve for crankcase ventilation Vauxhall Opel 5607187, Opel 5607258, Opel 5607159, Opel 5607592, GM 55558673, GM 55556284, GM 55564395 - Vanos BMW Repair kits for cars
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