Exhaust

Technical Information and Restoration Parts for the 928

Exhaust System (Max 50 Points)

There are a number of modifications that are made to exhaust systems from headers to the elimination of various components. It is the preference of the buyer as to whether any of these up grades are of value. One area of concern to the new buyer is the possible lack of smog equipment. Some states do not require periodic emissions testing. It is common in these states for people to remove catalytic converters and smog pumps. This can be an added and unexpected after sale expense when purchasing cars out of state.

	Smog Pump - All U.S. models required a smog pump except the 1980. Many of the Euro models do not have smog pumps. Smog pumps can also wear out. (Deduct 7 points for a missing smog pump)
	O2 Sensor - Starting in 1980 the Catalytic system included an oxygen sensor to monitor emissions. This is a serviceable part and designed to be replaced every 20K. The early models had a counter that keeps track of mileage and turns on a light on the dash when the time interval is up. (Deduct 7 points for a bad O2 sensor)
	Catalytic Converter - The most critical and expensive component of the emission system is the catalytic converter. A catalytic converter is very efficient in converting some very poisonous and noxious gases to harmless chemicals. It uses a catalyst such as Platinum or Palladium in the presence of heat to do this conversion. While the catalyst to such a reaction is by its nature never used up, in the real world garbage collects inside the converter and over time can clog it up and restrict flow. (Deduct 20 points for pre 1981 cars for a bad cat, 40 points for later cars)
	Heat Shields - The low ride of the 928 and the heat generated by the exhaust system requires a heat shield to prevent the heat from radiating into the passenger compartment. Heat shields over time can come loose and rattle or just be left off. (Deduct 5 points for missing of bad heat shields)
	Mufflers - There are a number of mufflers on the 928 more or less depending on years. These mufflers are supported by hangers that can break. Also it is common to by pass one or more of the mufflers to improve the "sound". (Deduct 7 points for each bad or missing muffler)
	General - The general condition of the exhaust system should be inspected for missing hangers and bent or leaky pipes. (Deduct up to 20 points for bad exhaust system condition)