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YOUR RESEARCHFan noise
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Install topgear eurosport x-pipe
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I noticed this same noise.....after I installed a TopGear Eurosport X-pipe with 200 cell cats.
Leading evidence: 'Install topgear eurosport x-pipe' (no explicit attributable resolution; this is a reported action or suggestion). Across 1 matching discussions, The most frequently discussed action is 'Install topgear eurosport x-pipe' (1 discussions). For that action, 0 discussions report a resolution and 0 report an unsuccessful attempt. No action has an explicit, attributable resolution report under the current rules. These are forum reports and suggestions, not a confirmed diagnosis.
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Hi everyone.....this is one of the best porsche sites available out there..whith that said i have a small issue that i cant seem to figure out.
I have a 2003 996 that makes this semi loud fan noise from the engine bay when i come to a stop at a red light and as soon as i tap on the gas pedal it goes away. Ive had a 2000 996 before this one and never had that issue and i don't belive its the fan on the engine lid because ive heard that run and it sounds nothing like it.
Hi there pp
I read a post from Loren that it's the airpump. I'm not sure. I thought at first that it was a fan - I hear the noise when the engine is warm and I come to a halt, say parking up in my driveway but it also deos it at traffic lights. It seems to do it more if I apply the handbrake.
All very odd. Does it stop if I press the accelerator. I don't know, I'll try it out. I'm stuck on the drieway for the time being though as the local council have sprayed bitumen all over our road and covered that in limestone chippings. I don't want to drive it until these chips have become well embedded. 'Cos of the idiot doing 70mph coming the other way./
air pump is inside of engine bay in front of left knee cap when you are standing gazing into the engine bay. It comes on for ~30 seconds to help "light" off the cats when car is cold. often sounds like an angry mini vacuum cleaner. Can also start at other times during engine operation.
http://www.renntech.org/forums/topic...%2Bair+%2Bpump
Ah, mine doesn't, you see. It sounds like a whiny hum, that's why I thought it was a pumpy fan noise. I've listened to all the youtube 996 engine noises and it's not a bearing, not a loose belt, not the gearbox.
I'm wondering if it's connected with the aircon, though it does it whether I have the aircon on or not. So, it can't be, I suppose.
The air pump is an anti-pollution device. it is there to introduce "fresh" air into the system upstream of the cats. This helps keep them hot enough to work efficiently.
You could unplug the connector and see if the noise you hear is the pump. You might get a check engine light that may or may not clear when you reconnect.
Reviving thread. I noticed this same noise.....after I installed a TopGear Eurosport X-pipe with 200 cell cats. Makes sense that it's the air pump desperately trying to dilute the increased emissions the O2 sensors are detecting? The car has had a CEL since the day I installed the X-pipe (even though TopGear claims their 200 cell pipe shouldn't throw a code).
Not how it works. Sai pump turns in for a predetermined amount of time on a cold start.
What code do u have. Im betting its a cat effieciancy code which has to do with the o2 sensors and u probably need extenders for the rear sensors
Hrm, your explanation makes sense also. I'll have to find a code reader. But then I wonder why are we (OP, me) getting that noise when the engine is warm? I'll have to listen on next cold start to see if it's there when cold as well. Majority of times I've noticed it are coming to a stop in traffic and returning home, pulling into garage, handbrake up.
