droning/pump noise from Rear of Car
10-24-2014, 01:44 PM
#16
Race Director
HI Chaps,, Sorry for the late reply,,
the noise is on startup , comes from the back of the car , sounds like a blowing exhaust manifold but isnt as the noise stops after car has run for about 5 mins, sounds like some sort of pump, had a fault code with secondry air system and OPC changed a valve if that help diagnose, Can it be a pump that sucks in hot air to intake when engine is cold and then again if emissions are high / unburnt mixture ? which is y it maybe comes on after about 15 mins ??
the noise is on startup , comes from the back of the car , sounds like a blowing exhaust manifold but isnt as the noise stops after car has run for about 5 mins, sounds like some sort of pump, had a fault code with secondry air system and OPC changed a valve if that help diagnose, Can it be a pump that sucks in hot air to intake when engine is cold and then again if emissions are high / unburnt mixture ? which is y it maybe comes on after about 15 mins ??
This is switched on at cold start and runs for a while -- how long depends upon (among other things) the ambient temperature.
The pump is intended to feed air to the exhaust so unburned fuel in the exhaust has sufficient air to burn in the exhaust and this helps warm up the converters.
The pump can go bad and usually it gets noisy.
The secondary air injection pump shouldn't come on again after it has run at engine start under normal conditions.
However, I seem to recall that the secondary air injection system can be triggered if the converters get too cold. In this case the DME would enrichen the mixture some and trigger the air pump to inject fresh air into the exhaust to burn this fuel and attempt to bring the converters up to operating temperature.
At the back of the car with the engine compartment lid open but being very careful you should be able to determine if the secondary air injection pump is running not only at engine start but when the noise appears after 15 minutes. If it is running then and there are no error codes this suggests the pump is on and for the reason I covered above.
But the pump could still be noisy which might be a sign it is going bad. It can also be due to an air leak from one of the secondary air injection hoses but I would think the CEL would be on but maybe not if the leak wasn't that bad.
If the noise appeared after the valve was replaced, this suggests an air leak from a hose that was disturbed when the valve was replaced, assuming the valve that was replaced was located on the engine.
10-26-2014, 11:19 AM
#17
8th Gear
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Just checked my opc paperwork , and it has had the following ''replaced secondary air injection system vacuume control valve'' part number : p7pp.906207. change-over val .. how hard is it to replace ? and what kinda cost are we talking ?
10-29-2014, 12:39 AM
#19
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10-30-2014, 11:55 AM
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Thanky you kind gents !,,, I will check for air leaks as advised, and also check the Diverter valves , and might clean the MAF with MAF cleaner , ,, anything else i should check ? can the secondry Air pump be overhauled ??
10-30-2014, 09:31 PM
#21
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it'll just sound like a very small tea kettle coming to boil when your at hi temps and it will be an oddity that is immediately eliminated by engaging the clutch. it is odd most annoying and i would venture most "newer" owners to the cars have purchased ones that have had that ps reservoir replaced which was porsches solution while the cars were under warranty.
thankfully
