thesmokinggasket

VERY late response, but yeah, it was a blown head gasket. Got the engine out and swapped them for fresh ones in my bedroom lol. Not bad for a first timer!

Filled the radiator using one of the buckets to get rid of air in the coolant system after I had replaced the water pump and timing belt. The problem existed before I had done anything to the coolant system. Both fans are working properly and turning on once the car has warmed up. I haven't pressure-tested the coolant system yet nor checked any of the cylinders. Primarily runs rough on startup prior to the engine warming. No sign of oil-coolant mixing so far but I might try one of the exhaust gas tests to further verify the issue isn't head gasket related. Forcing the car into limp mode seems like a good idea Ill try that when I get home today.

New here but starting to lose it hoping some of you have some nuggets of wisdom. My 2011 Impreza started overheating about a week ago at around 130,000 miles. Ended up towing her home. Currently has a rough start and occasionally misfires also overheats after about 15 minutes at idle. I haven't been driving it around due to the quick overheating issue. The code reader gave me P0172: A rich mixture through the O2 sensor and P0301 for a misfire in cylinder 1. I've swapped the MAF sensor, front and rear O2 sensors, cleaned the air intake, and changed the timing belt water pump assembly for the heck of it. The code reader says I'm running a -25% fuel trim which to my knowledge means the ECU thinks the engine is running rich and is pulling fuel. My hunch would be that the ECU is pulling from a faulty sensor and is causing the car to run lean and overheat. Also looked at the radiator, hoses, cooling fans, and thermostat and couldn't find any problems. Not sure what to replace next, I could start tearing into the fuel regulator, and injectors but my gut feeling is that it's something electrical. Any help or thoughts would be appreciated