: 00 STS Air Pumps; how many of them?



derone
12-10-08, 06:28 PM
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?

Submariner409
12-10-08, 06:46 PM
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.

derone
12-11-08, 01:25 PM
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.

FrankT
12-19-08, 07:15 AM
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.

derone
12-19-08, 09:49 AM
Hey thanks for the info...mine was an early production '00, like Dec '99 if I remember correctly.

ejguillot
12-19-08, 01:44 PM
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.

FrankT
12-19-08, 08:50 PM
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. :thepan:

Ranger
12-19-08, 10:42 PM
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.

FrankT
12-20-08, 08:21 AM
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.

CadillacSTS42005
12-20-08, 08:53 AM
03 STS
one pump
two valves

FrankT
12-20-08, 09:33 AM
03 STS
one pump
two valves

99 STS, no pump, no valves, and rust on the left rear 1/4. :(

FrankT
12-20-08, 09:46 AM
I think that one control valve didn't come into production till the 04 or 05MY Deville /DTS. Sorry if I confused anybody.:o

Submariner409
12-20-08, 11:38 AM
2002 mid-run STS = 1 pump, 2 valves (front and rear banks).