Engine Performance problem
1995 Toyota Corolla 4 cyl Front Wheel Drive Manual 285000 miles
I have a toyata corolla 2e engine that was recently overhauled. Piston rings were replaced with standard size since the piston space were still tight. Replaced parts were piston ring, valve seal, cylinder head gasket, sparkplugs, oil seal, oil filter, oil. After overhauling I've noticed that there were still oil leak under the oil pan but the engine performance that time was good no smoke, good acceleration, good timing. I've returned the car for back job. They've fixed the oil leak, but I've noticed the performance went bad and black smoke came out, the engine sound slight scratchy, not fine. So I've returned again the car, but still there's a black smoke coming out.
Black smoke is an indication of a rich mixture. This is most likely a sensor failure, coolant temp, MAP etc.
You should have a ckeck engine light, if so short Te1 and E1 in the diagnostic port (engine off, ign on) and get the codes.
A rich engine will (can) wash the oil film from the cylinder walls, and dilute the oil in pan possibly resulting in main bearing damage, as well as overheating the CAT.
So, get it fixed ASAP.