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2006 Cadillac STS 1SC
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383 Posts
Discussion Starter · #1 ·
'06 STS V6. Sometimes in the morning when it is approximately 40-50 degrees, the car will try (very hard) to start and it will fail. When I try again, it always works normally with no hesitation or anything. Any idea what is going bad?
 

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06 STS-V & 06 STS 4 (sold 2016)
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2,761 Posts
Possibly leaky injectors. They can leak while sitting for a while and can be affected by temperature. Basically the engine becomes temporarily flooded.
 

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2006 Cadillac STS 1SC
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383 Posts
Discussion Starter · #3 ·
Is this anything that needs any special attention or immediate attention? Will it get worse or cause other problems? Can it go unrepaired?
 

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2007 Cadillac STS
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182 Posts
I am going to agree with carter's_sts on this one. When is the last time the fuel filter has been changed? If you haven't run injector cleaner through it yet, this would be a good time to do that. Let it consume a tank of treated fuel and see if it still misbehaves.
 

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2014 XTS V-Sport Platinum
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2,431 Posts
If it is leaking fuel injectors, the problem is likely the fuel pressure regulator. This was a common issue on the FWD Northstar engines, and fairly easy to replace.
 

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2006 STS 1SG & 2007 STS 1SE
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21 Posts
If it's leaky injectors, there will be black smoke from the exhaust when it does start.
 

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2006 Cadillac STS 1SC
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383 Posts
Discussion Starter · #7 ·
Thanks everyone. I will look for the black smoke the next time this happens. And I dont remember the last time the fuel filter was changed... if ever.
 

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2006 STS 1SG & 2007 STS 1SE
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21 Posts
A bad coil should store codes. When did you last have a dealer check it out?
 

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2006 Cadillac STS 1SC
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383 Posts
Discussion Starter · #10 ·
I had the car in for a 32pt and an oil change at the dealer about 6 months ago. The car has actually been doing this for about 6 months or so, but prior to a couple weeks ago, it had only done it a total of about 4 times. Now it does it every three mornings on average. I just realized, however, that a month ago it did it after sitting for only an hour or two.

No check engine lights ever come on. Even after a failed start.
 

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2007 Cadillac STS
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182 Posts
These are the things I would do,

*Hold the ACC button till the car turns on (Engine off) make sure you hear the pump run for atleast 2 seconds.
*Run a bottle of Injector cleaner through the fuel system, also replace the fuel filter
*Check all grounds, Make sure they are clean and tight. If you have a Digital Volt Ohm Meter (DVOM) check to make sure the resistance between the ECM housing and the battery's negative cable is less than .5 ohms
*If you have an OBDII software that you can read live sensor data (after vehicle has been sitting for a good couple hours) check and see if the IAT and ECT readings are +/- 5 °F within each other
*Check the Fuel Pressure (55-60psi). The fuel pressure will drop when the fuel pump stops operating. After the fuel pump stops operating, the fuel pressure should stabalize and remain constant.
*Check the condition of the spark plugs, and make sure no oil or moisture has breached its way into the ignition coil tube.

Hope this helps, If you still can't figure it out I'll be glad to help
 

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2006 Cadillac STS 1SC
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383 Posts
Discussion Starter · #12 ·
I only have the means to do number 1 and 2. I don't know a whole lot about cars.
 

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2006 Cadillac STS 1SC
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383 Posts
Discussion Starter · #16 ·
So, to report back. I haven't changed anything or really checked anything, but the problem hasn't occurred even once within the last few weeks. Is there any reason why this problem would be intermittent with very long periods between occurrences? Does that rule anything out?
 

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1966 Fleetwood Brougham 2006 STS-4 1999 Deville Concours
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1,493 Posts
I am tracking this thread for more tips. My symptoms are the same: intermittent failed start, starts on 2nd attempt. No ryhme or reason when it will happen. Cool or colder temps will increase occurance which could mean battery. Fuel system svc'd last month. I have never seen any smoke after second attempt (using remote start).

I will check and eliminate the other items on the list matt provided (I'll have to borrow an OBDII). For me I think it is my battery, I think it is the original. Thanks for the info.
 

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2016 XTS
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562 Posts
My motorcycle is pretty much the same way. If it has been sitting overnight, it won't start on the first attempt. Second attempt fires right up. Although that is pretty common on my motorcycle. It's just the nature of the beast :)
 
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