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Post by wind82 on Oct 17, 2012 21:47:23 GMT -6
Does anyone know what the stock idle speed is on a 3.5 aurora ? How low can you take the rpm's on idle without harming the engine ? I would like to lower The rpm to save on fuel but it is not worth damaging my car .
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Post by renaldo0613 on Oct 18, 2012 0:15:35 GMT -6
And how would u achieve lowering the rpms at idle?? I would imagine at running temp rpms would be somewhere in the 600-800. They idle higher than the 4.0
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Post by wind82 on Oct 18, 2012 6:48:20 GMT -6
My aurora has never idled at 600 , when i got it it was around 1000 rpm at idle. I started looking for information about this after i cleaned the throttle body and idle air control my rpms went down to about 860. After the car was driven for about a week i noticed a change in the mpg, this made sense but made me curious . I know that from time to time the screw on the throttle body connected to the throttle cable has to be adjusted . I connected a live data enable scanner and adjusted the screw until the cars rpms were at 750. At this rpm the car has been even more quiet and saves yet even more gas . I know the cars computer can and may adjust the rpm level over time. I also know the computer can be flashed to change the default value for idle speeds, this is why i want to know what the stock idle speed should be and at what point it can harm my engine.
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Paulaurora
Super Moderator 
Posts: 3,842
Staff Member
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Post by Paulaurora on Oct 18, 2012 7:00:26 GMT -6
700-750 is good idle.
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Post by ntrenn on Oct 18, 2012 9:09:06 GMT -6
When your idle gets sub 600, you will start getting low oil lights during parking maneuvers.
About 700-750 is normal.
Curb idle is supposed to be set by the ECM, but as you found out, one can override that by adjusting the throttle stop screw(at least in the higher direction). Usually that is done to cover up other issues, like IAC valves inoperative or similar.
Having just done the coolant crossover gaskets, there were other things that we found that could contribute to wrong idle....backfire valve not seating, leaking intake gaskets, split PCV line fittings, leaking manifold adapter O-ring and gasket. All in, those parts are about $50 (35 for the backfire valve) and between that and cleaning the TB, it made all the difference in the world for idle stability.
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Post by robaurora01 on Oct 18, 2012 18:23:23 GMT -6
if your rpm is going above 800 on WARM idle not cold then you need to take the TB off and clean it properly with TB cleaner p.s. ull need a new gasket if you do such because you wouldn't believe the amount of gunk is probably stuck on there
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