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Registered User
Join Date: Sep 2012
Posts: 3
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Noise from airbox
Hope someone can help me out. I have a 89 911 with 141K. While driving yesterday, about 2 hours into a drive, a strange noise started while accelerating through 2000-2500 RPMs. I initially thought it was the transmission or a heat shield vibrating but the transmission was shifting fine and once the engine cover was opened the noise seemed to be coming from the air-box area. The engine runs fine, no lack of power or misfiring however it may be running a bit rough at idle. The noise is hard to describe, it sounds like a vibration with a lower pitch growl to it, it is not intake noise, not a normal intake noise anyway. The noise appears around 2000-2200 rpm and seems to go away after 2500 or I cant hear it anymore due to other engine noises.
Does anyone have any idea what this may be? Loose intake manifolds? Air-box? Cylinder not firing at low RPM? Thanks |
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09-10-2012, 06:10 PM
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Go Speedracer, go!
Join Date: Aug 2002
Location: Indianapolis
Posts: 1,951
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Failed timing chain tensioner possibly? Does it sound like dragging a metal chain across a metal trash can?
Last edited by SpeedracerIndy; 09-10-2012 at 07:30 PM.. |
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09-10-2012, 07:20 PM
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Registered
Join Date: Aug 2008
Location: sectors R&N, SE Pa
Posts: 3,117
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Dan '87 Targa Carrera 3.2 - Fabspeed Cat Bypass, M&K Muffler, SW Chip Venetian Blue |
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09-10-2012, 08:27 PM
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Join Date: Sep 2012
Posts: 3
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It doesnt sound like dragging metal chains, It may be similiar to the noise from the other thread but my noise only comes on at 2000-2500 RPM.
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09-11-2012, 11:02 AM
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Although maybe different from yours',.....I occasionally heard a vibration-based noise,..and ultimately found it to be a loose nut on the cat converter shield......go figure?
That is, to say, be sure (first) that nothing is loose somewhere...... I hope yours is as benign as mine. BEST! Doyle
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Recording Engineer, Administrator and Entrepeneur Designer of Fine Studios, Tube Amplifier Guru 1989 Porsche 911 Carrera Coupe 25th Anniversary Special Edition Middle Georgia |
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09-11-2012, 02:19 PM
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Registered User
Join Date: Sep 2012
Posts: 3
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It turns out that the bolts holding the airbox to the throttle body were loose and one was backed out and sitting inside the box. Tightened all of them back up and it runs fine. Thanks for the responses.
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09-13-2012, 11:22 AM
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