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Dan
Dan, Technician
Category: Cadillac
Satisfied Customers: 24214
Experience:  Independent Shop Experience, 2 Year Automotive Diploma, & Access to Information Database
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I have a 2005 Cadillac STS. I believe I have a leaking vacuum

Customer Question

I have a 2005 Cadillac STS. I believe I have a leaking vacuum hose causing a misfire and tranny shifting issue. Where would I look for this hose? I've look, but don't see anything. FYI...both issues started at the same time.
Submitted: 2 years ago.
Category: Cadillac
Expert:  Dan replied 2 years ago.
Hello, my name is ***** ***** I'm here to help get your problem solved. Is your check engine light on? This transmission is not vacuum operated so can not cause a vacuum leak.
Customer: replied 2 years ago.
The engine light comes on when it struggles to shift going uphill, but shuts off once it gets on level ground. Could it be just badly misfiring?
Customer: replied 2 years ago.
I do have a irratic misfire at idle, at least that's when it's noticeable.
Customer: replied 2 years ago.
I plan on changing the spark plugs tonight, but I need to know what the intake manifold and spark plug torque should be. Also the bolt order in which to tighten down the manifold.
Expert:  Dan replied 2 years ago.
Does check engine light flash off/on? Have you checked codes yet? It sounds like you probably have a bad coil. V6 or V8 engine?
Customer: replied 2 years ago.
Yes it flashes off and on...then shuts off. It's a V6.
Customer: replied 2 years ago.
I don't have anything to check the codes.
Expert:  Dan replied 2 years ago.
It definitely sounds like a bad coil. At this point I'd recommend getting diagnostic codes checked which can be done at your local parts store for free. It should indicate what cylinder is misfiring. Then swap coil on that cylinder with another cylinder to see if misfire follows coil, if so replace the coil. This would be around $200 to have done at a shop. Let me know if you have more questions, thanks.
Customer: replied 2 years ago.
Would that be the reason I feel the jerking when it heavy downshifts?
Customer: replied 2 years ago.
Hard downshifts.
Expert:  Dan replied 2 years ago.
Probably, especially if shifting and misfiring happened at the same time. When engine misfires it effects shift points. Let me know if you have more questions, thanks.
Customer: replied 2 years ago.
Do you have the torque specs for the intake and spark plugs?
Expert:  Dan replied 2 years ago.
Spark plug is 15 ft lbs and you shouldn't need to remove intake. Here are instructions for coils but you need to start by using scan tool or spark tester.
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https://www.dropbox.com/s/avnasp8r7x1bxou/sts1.pdf?dl=0
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https://www.dropbox.com/s/vlp2oe5m5dqn0of/sts2.pdf?dl=0
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Customer: replied 2 years ago.
The intake overhangs the ignitor coils, at least on 2 cylinders. Is there another way to remove them without doing so?
Expert:  Dan replied 2 years ago.
No but there is still a good chance it is one of the coils more easily accessible. Let me know if you have more questions, thanks.