Just acquired the above - am trying to find out what an assembly does in the engine compartment. Nearside next to battery and windscreen wash reservoir there is a circular assy about 6" diameter, 3" deep which first start of the day runs at high speed for about 3 minutes. Is it a cooler of some sort, or a compressor??
cheers
Jeff
probably the air pump to keep the emissions right.
Indeed. Its the secondary air pump, which injects air into the exhaust manifold for a time on cold start-up. This allows any excess fuel in the exhaust to burn, and gets the catalytic converter up to temperature more quickly.
Anthony Remove eight from email to reply.
It is the auxilary air pump. This runs for upto 45seconds only at cold start and pumps fresh air into the exhaust system just behind the exhaust valves. Its purpose is two fold:
1) to burn off excess hydrocarbons in order to bring the cat up to temperature more rapidly. 2) to fool the o2 sensor into thinking the mixture is leaner than it actually is, to prevent the ecu from leaning it off too much and presenting hesitation / drivability problems immediately after cold start.Ensure yours isnt able to fill up with water as they often do, then burn out which will result in the MIL lamp lighting up on the dash.
Tim..
It is the auxilary air pump. This runs for upto 45seconds only at cold start and pumps fresh air into the exhaust system just behind the exhaust valves. Its purpose is two fold:
1) to burn off excess hydrocarbons in order to bring the cat up to temperature more rapidly. 2) to fool the o2 sensor into thinking the mixture is leaner than it actually is, to prevent the ecu from leaning it off too much and presenting hesitation / drivability problems immediately after cold start.Ensure yours isnt able to fill up with water as they often do, then burn out which will result in the MIL lamp lighting up on the dash.
Tim..
Many thanks Tim - we learn something every day!
Cheers
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