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2002 Seville SLS
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20 Posts
Discussion Starter #1
I have a 2002 Cadillac Seville SLS and when I first start it and it's idling/auto choke is on it makes a high pitch sound, but once the choke goes off the high pitch sound stops. I have no idea what it could be besides something dealing with the idling, can anyone give me more info on this, thanks.
 

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2002.5 F55 CORSA STS, 2014 Explorer XLT FWD
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68,458 Posts
Re: High pitch sound

Two possibilties:

1. The AIR system - that blower and vacuum-operated check valves that supply fresh air to the exhaust manifolds on cold start in order to quickly light off the cat. The blower can sound like a vacuum cleaner when/if the lower plastic cover breaks and falls off. Inside the LF fenderwell liner, front part. Discussed in these forums about once every two weeks.

2. Maybe a small vacuum leak, pronounced at fast idle.

One morning, open the hood and have an assistant start the engine normally. Snoop around.
 

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White Diamond '03 DHS (with DTS floor shift)
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86,783 Posts
By "once the choke goes off", I assume you mean that the RPM drops from about 1200 to 900 (40 seconds or so). If so, and that high pitched sound only lasts for those 40 seconds, I'd put my money on the AIR pump (#17). Could be a failing bearing or a disconnected cover slash silencer (#8 & 9)..



Located in front of the LF wheel (#2).

 

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'02 ETC 34,000 miles 2002 F55 STS 83,000 miles, 2016 Challenger SRT 392, 6 Sp.
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264 Posts
My Eldo is doing something similar. Not sure if it's exactly the same as the problem the OP has, but I hear a high pitched whine for just a few seconds upon cold start. Sounds like a bearing going bad to me. Does the Eldo have the same air pump setup as the Seville?
 

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2002.5 F55 CORSA STS, 2014 Explorer XLT FWD
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68,458 Posts
Yes. All this series has some sort of AIR system. The pump/cover/water trap is inside the LF fenderwell liner, hoses run to the AIR check valves - one next to the lower radiator hose (driver's side, low), and one on top of the right (rear) cam cover.

AIR runs a short burst, a long burst, 20, 30, 40 seconds or never, depending on ambient temperatures and time since last start/coolant temperarture.
 
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