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Discussion Starter #1
Hi all,
I have a question about vacuum levels in the 3.4 CS engine. I have a miss or vibration at lower and mid RPM ranges (1150 to about 3K). The car seems slightly down on power, but not substantially so.

I've read the various postings about AOS/VOS issues, and the engine running rough with the oil cap loose or removed.

In my case, when the oil cap is on tight and the engine is running, there's so much vacuum at the filler tube that it is collapsed and fully flat. I can remove the cap by hand, and the engine runs extremely rough when I do.

I'm questioning the collapsed filler tube...could that possible be normal, or do I have something else going on???

Unfortunately no available Durametric or testing equipment. Appreciate any input you all have.

Thanks!!
 

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CGH,
The amount of vacuum you are seeing might be a ruptured AOS diaphragm. Are your inlet ducts oily and or is the car smoking?

Rob
 

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Discussion Starter #3
Rob,
No smoke, but I haven't looked at the inlets. Will do that this afternoon.

Thanks!
 

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Discussion Starter #4
It was the AOS.... replaced it this morning and problem solved. Power seems back up slightly, idle definitely smoother.
 
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