Expert: Robert Summers - 11/7/2007

Question
My catalytic converter went out on my 2002 Malibu with 115000 mi. It has recently started using 1 qt of oil every 5 or 6 tanks of gas. I pulled the o2 sensor to release the back pressure and determined that the converter was bad because the power in the engine returned. There was alot of smoke escaping as well. Assuming the compression test will be o.k. what else can I check besides the EGR valve and the pcv valve that may be causing the blow-by?

Answer
Hi Gary... Remove the cat and put in test pipe... drive the car if oil consumption is the same do a compression test, first dry then wet. if compression rises in the wet test you have a ring problem meaning compression is going past the rings and venting via the pcv. make sure your pcv is free (rattles) when you shake it. if stuck open it will suck the oil from the engine causing oil burning... hope this helps