i drive a 98 A4 2.8 98000mi recently i noticed that there is a whining/fan running and feel air blowing from beneath the airfilter box. it seems to run for 10sec then stops and runs again. this happens whether the car is running or not.this keeps going on for hours. any idea HELP!!

 

most likely a bad sensor pull up codes and get back to us

 

ok will do... but do you have any idea what might be running? both radiator fans are both off. seems wierd for somthing to be running like that..

 

thanks,

 

That is strange. Your ECU probably has something to tell you. Maybe secondary air?

 

yeah deff the secondary air pump

 

do u guys hav any pics on where it is, or what it lokks like. i hav no idea where it might be.
is the secondary air pump difficult to change or expensive?

 

It is expensive - around $300. It's at the very bottom front of the engine compartment on the passenger side. It's secured by 3 or 4 screws into a circular metal bracket.

The pump itself could be shot or you could have a bad hose to it. Also, it's normal for it to make some noise when you first start the car up, though it shouldn't be too bad. You shouldn't feel air from it though.

 

Lots of people choose to simply remove the whole system. Reasons being weight reduction, clutter reduction and lack of consequences. Basically secondary air injection (SAI) pumps warm air from the intake through the catalytic converter for cold starts, thereby heating the cat to optimal temperatures faster and cutting down on emissions. The car will still pass emissions without it. I believe you will get a check engine light, but there's supposedly a fix involving a resistor equal to the resistance of the SAI system being wired in series. I'd like to do it, but I have no reason.

 

I removed mine. Here's a modified version I did of the vacuum system from the Bentley download that describes my car at the moment: http://img685.imageshack.us/img685/6...audivacuum.png