00 STS Air Pumps; how many of them?
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Northstar Engines and System Technical Discussion Discussion, 00 STS Air Pumps; how many of them? in Cadillac Engine Technical Discussion; Mine has 2 pumps, but in the FSM, they show either none, one, or two. Anybody know the why GM ...
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    derone is offline Cadillac Owners Fanatic
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    00 STS Air Pumps; how many of them?

    Mine has 2 pumps, but in the FSM, they show either none, one, or two. Anybody know the why GM had some many different setups?

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    Submariner409's Avatar
    Submariner409 is offline If it won't run, chrome it
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    Re: 00 STS Air Pumps; how many of them?

    Depends on the emissions specifications (50 state, lower 48, California) and the engine/PCM programming as well as the model of cat. If the cat lights off with a minimum of extra oxygen, depending on application, then maybe none or one pump.

    There also was a thread earlier in '08 concerning the number of A.I.R. valves/solenoids mounted on the engine (sometimes one on the rear cam cover, sometimes that plus one in front of the water pump/"upper hose" area).

    Don't confuse the emissions pump(s) with the rear level control compressor.......

    Run your RPO's......the emission compliance package is in there.

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    derone is offline Cadillac Owners Fanatic
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    Re: 00 STS Air Pumps; how many of them?

    Oh, I saw both of them when I had the bib off to change the fog light bulb. There was one on each frame horn underneath the 'bib' cover in front.

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    FrankT's Avatar
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    Re: 00 STS Air Pumps; how many of them?

    Quote Originally Posted by derone View Post
    Oh, I saw both of them when I had the bib off to change the fog light bulb. There was one on each frame horn underneath the 'bib' cover in front.
    Yes, you saw two AIR pumps, one for each bank. The two pumps were only used in early production, 2000MY only. Two pumps were an over kill, one pump does the trick. As far as why did they use the 2 pump set up,
    IMO, they found out that one pump will push enough air into the exhaust system to light off the cat, and meet the emission standard.

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    derone is offline Cadillac Owners Fanatic
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    Re: 00 STS Air Pumps; how many of them?

    Hey thanks for the info...mine was an early production '00, like Dec '99 if I remember correctly.

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    ejguillot's Avatar
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    Re: 00 STS Air Pumps; how many of them?

    Quote Originally Posted by FrankT View Post
    Yes, you saw two AIR pumps, one for each bank. The two pumps were only used in early production, 2000MY only. Two pumps were an over kill, one pump does the trick. As far as why did they use the 2 pump set up,
    IMO, they found out that one pump will push enough air into the exhaust system to light off the cat, and meet the emission standard.
    That explains why mine has 2... production of 8/99. Be nice if it was only 1, less to go wrong.

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    FrankT's Avatar
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    Re: 00 STS Air Pumps; how many of them?

    Quote Originally Posted by ejguillot View Post
    That explains why mine has 2... production of 8/99. Be nice if it was only 1, less to go wrong.
    Yes, and less expense, GM did not do the homework and thought that the N* needed two AIR pumps and two control valves to light off the cat to meet emissions for 2000MY.

    From mid 2000 and to current model years, the N* has one pump and one control valve, the rear bank.

    Using only one pump and one control valve is a huge cost savings for both GM and the customer. Talk about an expensive lesson learned.

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    Ranger's Avatar
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    Re: 00 STS Air Pumps; how many of them?

    From mid 2000 and to current model years, the N* has one pump and one control valve, the rear bank.
    I think I have only one pump, but I have two control valves.

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    FrankT's Avatar
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    Re: 00 STS Air Pumps; how many of them?

    Quote Originally Posted by Ranger View Post
    I think I have only one pump, but I have two control valves.
    Yes Ranger that is totally possible, through emission testing and cost savings direction, GM found out that one pump and one control valve was sufficient.

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    Re: 00 STS Air Pumps; how many of them?

    03 STS
    one pump
    two valves

  12. #11
    FrankT's Avatar
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    Re: 00 STS Air Pumps; how many of them?

    Quote Originally Posted by CadillacSTS2003 View Post
    03 STS
    one pump
    two valves
    99 STS, no pump, no valves, and rust on the left rear 1/4.

  13. #12
    FrankT's Avatar
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    Re: 00 STS Air Pumps; how many of them?

    I think that one control valve didn't come into production till the 04 or 05MY Deville /DTS. Sorry if I confused anybody.

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    Submariner409's Avatar
    Submariner409 is offline If it won't run, chrome it
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    Re: 00 STS Air Pumps; how many of them?

    2002 mid-run STS = 1 pump, 2 valves (front and rear banks).

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