2010 2.4 rough idle when hot

[IronHorseDriver]

OK, I know someone who has a 2010 Equinox with the 2.4 engine. The engine ran out of oil and since the low oil pressure light didn't work, the engine blew. He got a fly-by-night mechanic who rebuilt the engine but the car is experiencing problems. The engine starts and runs but after about 20 minutes of driving the idle is erratic and it eventually stalls out at idle. Driving seems OK. The throttle body and fuel pump were replaced. The only codes coming up are "Evap system vent control circuit" and "Catalyst system efficiency below threshold". Any suggestions?

 

[Uluz2a6]

If no timing codes are present, I would ask you if the senoid on top of the cylinder head were replaced when engine was rebuilt and if so, are they GM units? There is one for intake and exhaust. Aftermarket units respond slower than GM equipment and once oil warms up they tend to cause iradic idle conditions. The catalyst efficiency code is from the original engine failing and damaging your catalytic converter I think.