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97 SLS
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Discussion Starter #1
hi again,
i got into a small fender bender a while ago.. all set now repainted and everything, however it disloged and crack that large vacuum resivoir behind the passengerside front fender,
I have read that this is the ebrake vacuum cannister, instead of replacing it, i removed the cannister and plugged the end of the vacuum line, its not leaking, nor can i find a leak anywhere else in the vacuum system,
however my car is acting like it has a vacuum leak, slightly high idle and dropped 2 or 3 mpg, would the lack of canister cause this? how can i check vacuum preasure?
thanks a bunch!
frank
 

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2010 DTS
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87,313 Posts
First off, just to use the correct words, vacuum is the absence of pressure. The vacuum "reservoir" is just that. It holds vacuum so that when you throttle up and the manifold vacuum drops, you still have vacuum to operate the things that need vacuum, like the HVAC air distribution doors. If you have a leak, everytime you get into the throttle, the HVAC will default to defrost mode (lack of vacuum). Also the system will bleed down when you shut down the engine and the parking brake will not release. Sounds like you have a leak somewhere. I would replace that reservoir and check all the vacuum lines.
 

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Uuuuhhhh.... What car?

After tracking down a real BEAR of a vacuum problem with my son's 97 ETC (code P0507 - High Idle), I now KNOW where all the vacuum lines should be sourced, where they're located, and what they do. One line especially, actually has a "hidden" connection to the intake manifold. I only found it by following the line on another ETC.
 

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97 SLS
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Discussion Starter #4
sorry, its a 94 seville sls,
ive trace all the vacuum lines, even tried a lil propane to see if i could get the even to rev.. no luck,
the only thing thats not how it should be is the lack of that resivoir.. the system is still sealed so i didnt think it would be a problem
 

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Is everything (vacuum-driven things) working properly? I'm unclear as to what your stated problem is... High Idle? Is that all? It should throw a code if high idle is due to a vacuum leak (maybe a 94 won't). You didn't state if there are any codes. Do you have any codes?

I'm going to make the "unsafe" assumption that the SLS vacuum routing in the engine area is similar to an ETC. If you are talking about the vacuum tank that I think you are (lives under the battery tray on an ETC), then it's line has a vacuum check-valve in it. If you've defeated the reservoir which normally provides a rather constant vacuum on one side of the check-valve, then I think the resulting vacuum system (without the reservoir) will be instantaneously sensitive to engine load because the vacuum (from the intake manifold) is not dampened by the reservoir.

I learned a long time ago that when it comes to fixing complicated stuff, fix the stuff that you KNOW is broken first. Sometimes the broken item has side-effects that you never thought would cause the observed symptoms.

Good Luck!
 
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