That weird noise @ start-up
05-10-2008, 03:11 AM
#1
Safety Car
Thread Starter
That weird noise @ start-up
You know that noise when you fire the car up, lasts for a couple mins (its a shorter time period after the first start of the day) and then you hear it wind down.
Its like a quiet high pitch noise...... harder to describe than I thought
Anyways, something tells me I knew what it was at one point but I cant remember.
Its like a quiet high pitch noise...... harder to describe than I thought
Anyways, something tells me I knew what it was at one point but I cant remember.
05-10-2008, 05:56 AM
#4
Melting Slicks
Member Since: Nov 2004
Location: Parkland Florida
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St. Jude Donor '09-'10
You're probably talking either about "Piston Slap" (which is more of a sewing machine tap...tap...tap) or a failing fuel pump (which is a steady highish pitched hum, do a search on the forum for piston slap or fuel pump and you'll get more than enough information.
Last edited by DRKMATTER; 05-10-2008 at 05:59 AM.
05-10-2008, 01:48 PM
#5
Racer
You know that noise when you fire the car up, lasts for a couple mins (its a shorter time period after the first start of the day) and then you hear it wind down.
Its like a quiet high pitch noise...... harder to describe than I thought
Anyways, something tells me I knew what it was at one point but I cant remember.
Its like a quiet high pitch noise...... harder to describe than I thought
Anyways, something tells me I knew what it was at one point but I cant remember.
-Rich
05-10-2008, 01:54 PM
#6
Safety Car
Thread Starter
Well its def not piston slap or valve noise, or really engine related.
Its done it from day 1, its not a problem noise.
Maybe I can try and get a sound clip.
Thanks!!
I hear it too
05-10-2008, 04:31 PM
#10
Team Owner
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05-10-2008, 05:19 PM
#12
Drifting
Member Since: Sep 2003
Location: 1994 LT1 Coupe 6-speed with FX3 & 2000 LS1 Vert 6-Speed with F45 Hunterdon County, NJ
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If the noise from the A.I.R. pump is noiser than you remember, it could imply one of the two check valves have started to fail, yet not quite enough or in the way so as to throw a code.
The check valves fail due to rusting from moisture and exhaust gases and can either not open enough or fail to close to hold back the exhaust gases (one on driver side connected to the exhaust manifold via a metal pipe -- easy to change, the other at the top rear of the engine, also mounted to a metal pipe that wraps around to the passenger side exhaust manifold -- PIA to change).
Also, the 'codes' are only based on the O2 sensors not heating up fast enough, so it does not advise of the reverse flowing of exhaust gases which can damage the rubber hose and the A.I.R. pump, nor does it advise when a slight imbalance between O2 sides heating-up exists.
As a barometer:
our 94 LT1's (100K) check valves were fine when changed last year just in case.
By contrast, our DD 2000 Pontiac TA (100K too -- same LS1 engine as in our 2000 C5) threw a code for the driver side. I replaced both, as the passenger side was also nearly stuck closed (thankfully, Pontiac moved the passenger side check valve to the passenger side of the engine, so it was just as easy as the driver side, unlike the PIA LS1 in the C5s).
The check valves fail due to rusting from moisture and exhaust gases and can either not open enough or fail to close to hold back the exhaust gases (one on driver side connected to the exhaust manifold via a metal pipe -- easy to change, the other at the top rear of the engine, also mounted to a metal pipe that wraps around to the passenger side exhaust manifold -- PIA to change).
Also, the 'codes' are only based on the O2 sensors not heating up fast enough, so it does not advise of the reverse flowing of exhaust gases which can damage the rubber hose and the A.I.R. pump, nor does it advise when a slight imbalance between O2 sides heating-up exists.
As a barometer:
our 94 LT1's (100K) check valves were fine when changed last year just in case.
By contrast, our DD 2000 Pontiac TA (100K too -- same LS1 engine as in our 2000 C5) threw a code for the driver side. I replaced both, as the passenger side was also nearly stuck closed (thankfully, Pontiac moved the passenger side check valve to the passenger side of the engine, so it was just as easy as the driver side, unlike the PIA LS1 in the C5s).
05-10-2008, 08:29 PM
#14
Safety Car
Thread Starter
