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My 2006 CTS with gm3.6l with 138,000 miles has been dying once it reaches normal operating temperatures. It runs strong but then dies all of a sudden... no sputtering, just instantly cuts off.
idles at about 1000 rpm when cold and then slowly descends to about 650 rpm as the engine heats up (Is this normal?)... and then it dies...(that part isn't normal...:))

If the engine is being revved above idle while the engine reaches operating temperatures, it does sputter for maybe 2 or 3 seconds and fights to stay running but ultimately dies every time.

I have tried replacing the crankshaft position sensor to no avail... dont know what to try/test/replace next! Any help would be appreciated!

Also the engine will always start up immediately when cold or right after it dies makes no difference... it will continue to die as long as the engine is warm, but runs great when engine is below operating temps.
 

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My 2006 CTS with gm3.6l with 138,000 miles has been dying once it reaches normal operating temperatures. It runs strong but then dies all of a sudden... no sputtering, just instantly cuts off.
idles at about 1000 rpm when cold and then slowly descends to about 650 rpm as the engine heats up (Is this normal?)... and then it dies...(that part isn't normal...:))

If the engine is being revved above idle while the engine reaches operating temperatures, it does sputter for maybe 2 or 3 seconds and fights to stay running but ultimately dies every time.

I have tried replacing the crankshaft position sensor to no avail... dont know what to try/test/replace next! Any help would be appreciated!

Also the engine will always start up immediately when cold or right after it dies makes no difference... it will continue to die as long as the engine is warm, but runs great when engine is below operating temps.
Check a spark plug for a worn down electrode.
 

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Thank you for the suggestion I will try this and let you know what I find, it might be a couple of days though as I’m on a trip right now.
 

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Thank you for the suggestion I will try this and let you know what I find, it might be a couple of days though as I’m on a trip right now.
It is a good place to start anyway. I only suggest that first because the symptom sounds a lot like what I had in an older Buick. Ran fine all the time, nice and smooth, then out of the blue it would die when at idle at traffic light. Then start right back up and no problem after. Then a couple months down the road, same thing. That continued once every couple months for a while, I didn't check into it, because it wouldn't do it much, figures I would just wait until it showed its ugly head for real. lol Then after about a year or longer, it did it slightly more often, but not by much. Then it would stall and when restart would run a little rough for a few seconds and then no problem. Fast forward a while and it would stall once a week and run rough for a few seconds, and then it began not starting up on the first try, it would take two attempts, then three. It was happening enough to be pretty annoying so I just decided to do a tune up. This was not my car it was my mothers car that I bought for her. SO I got some plug wires and plugs and some carb cleaner for the throttle body and air flow sensor etc. Pulled out the sparkers and OMG they were SO short lol. Well, after I got the new plugs in it never happened again.
So, I would check a spark plug first just to make sure it isn't that.
 

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2007 CTS 3.6 >128k miles
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Guido also mentioned the throttle body and MAF sensor. IME these can also affect idle performance especially if they haven't been cleaned for a long time. I have not seen it cause engine to stall but idle was definitely rough. Also, I presume the air filter is not clogged???

OP also asked whether 650 RPM is normal idle...yes, 650 is normal.
 

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It is a good place to start anyway. I only suggest that first because the symptom sounds a lot like what I had in an older Buick. Ran fine all the time, nice and smooth, then out of the blue it would die when at idle at traffic light. Then start right back up and no problem after. Then a couple months down the road, same thing. That continued once every couple months for a while, I didn't check into it, because it wouldn't do it much, figures I would just wait until it showed its ugly head for real. lol Then after about a year or longer, it did it slightly more often, but not by much. Then it would stall and when restart would run a little rough for a few seconds and then no problem. Fast forward a while and it would stall once a week and run rough for a few seconds, and then it began not starting up on the first try, it would take two attempts, then three. It was happening enough to be pretty annoying so I just decided to do a tune up. This was not my car it was my mothers car that I bought for her. SO I got some plug wires and plugs and some carb cleaner for the throttle body and air flow sensor etc. Pulled out the sparkers and OMG they were SO short lol. Well, after I got the new plugs in it never happened again.
So, I would check a spark plug first just to make sure it isn't that.
new spark plugs did not resolve the issue, still looking around for other issues. I also cleaned out the throttle body and MAF sensor to no avail. Thanks in advance for any other suggestions you may have
 

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Guido also mentioned the throttle body and MAF sensor. IME these can also affect idle performance especially if they haven't been cleaned for a long time. I have not seen it cause engine to stall but idle was definitely rough. Also, I presume the air filter is not clogged???

OP also asked whether 650 RPM is normal idle...yes, 650 is normal.
Yep, checked these and cleaned them, same problem. It seems to be an electrical issue as it is very consistent about getting to operating temperature and then promptly dying like the flip of a switch it goes from running strong to off....
I have also been revving it at the time it gets to operating temperature and it will still die even when above idle RPMs.

So I'm thinking something with electricals, which sounds like a nightmare on a cadillac bc there's so many wires. Any ideas what to check first?
 

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I agree that this issue is likely electrical, but it is difficult to know where to start without any diagnostic codes. Therefore, I would start by verifying that the major connections are tight: back of the alternator (you will need a 10mm deep socket and a long extension with U-joint), battery cables, and ground connection. I would also disconnect all of the sensors you can reach, apply dielectric grease to the contacts, and then reconnect them. If these don't help, I would take it to a shop to have things checked out before throwing more parts at it.
 

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I agree that this issue is likely electrical, but it is difficult to know where to start without any diagnostic codes. Therefore, I would start by verifying that the major connections are tight: back of the alternator (you will need a 10mm deep socket and a long extension with U-joint), battery cables, and ground connection. I would also disconnect all of the sensors you can reach, apply dielectric grease to the contacts, and then reconnect them. If these don't help, I would take it to a shop to have things checked out before throwing more parts at it.
Ill check this out and get back to you... thanks for the ideas!
 

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'93 SedanDeville 60 Special
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If I read this right the engine runs OK when cold but then peters out once engine temps comes up

If so the difference is the PCM ignores feedback sensors when coolant temps are low, that means PCM stays
in OPEN loop and uses open loop calibration values

Once coolant gets over 140 to 160 degrees the PCM would switch function in CLOSED loop mode, meaning it then would adjust as to what feedback sensors report such as O2 sensors, MAF, MAP, IAT and ECT

That would lead to some sensor or it's wiring is faulty or it could be low or no voltage, or of course the PCM is faulty
Else a bad or flaky ground.

You must use a OBD-II scanner and watch when the engine loop PID goes from open to closed and then see what the above sensors report.
Look at the fuel trim values, see if misfire or knock counters clicking away and that MAF and MAP values look OK

IF DTCs are not tripping, either the problem is something the PCM does not monitor or maybe someone tuned the PCM and turned the DTCs off to hide a problem
 

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If I read this right the engine runs OK when cold but then peters out once engine temps comes up

If so the difference is the PCM ignores feedback sensors when coolant temps are low, that means PCM stays
in OPEN loop and uses open loop calibration values

Once coolant gets over 140 to 160 degrees the PCM would switch function in CLOSED loop mode, meaning it then would adjust as to what feedback sensors report such as O2 sensors, MAF, MAP, IAT and ECT

That would lead to some sensor or it's wiring is faulty or it could be low or no voltage, or of course the PCM is faulty
Else a bad or flaky ground.

You must use a OBD-II scanner and watch when the engine loop PID goes from open to closed and then see what the above sensors report.
Look at the fuel trim values, see if misfire or knock counters clicking away and that MAF and MAP values look OK

IF DTCs are not tripping, either the problem is something the PCM does not monitor or maybe someone tuned the PCM and turned the DTCs off to hide a problem
Alright sorry I've been away from the forum for a bit, but i have some new information finally!

We got tired of idling the car inn our driveway so we just decided to risk getting stranded somewhere and do a moving test... So we first let it warm up in the driveway idling and then it died as usual and then we got bored so we took it out on the streets, and low and behold, it actually got better!

It bucked and coughed a lot on the first few accelerations, and was also blowing some bluish smoke... that was confusing, but it hadn't died yet, so we kept going. Eventually, the bucking/hesitation on acceleration had lessened but not completely gone away, but did not completely go away, but the blue smoke stayed...

Then on a harder acceleration while it was hesitating/coughing the MIL popped up... it shows P0366 (camshaft position sensor b circuit range/performance bank 1.)

More about the DTC:
I figured "oh sweet, its just a simple bad sensor, easy fix." Well I switched the two camshaft sensors on bank 1 (Which is the passenger side on this engine... right? not actually sure about that, so somebody fact check me.)
anyways I switched the two sensors, cleared the codes, and it still came back as sensor B bank 1... same code.
I figured if it was a bad sensor it would move to sensor A, but it stayed on sensor B. So there must be a wiring issue or the reluctor wheel on the inside is somehow messed up so the sensor can't read it... not sure where to start troubleshooting this so I would take any help you got. My ideas/hope is that bc the code is for the CIRCUIT, it could be a bad ground or wiring issue, but i dont know where the ground would be, so I could use some help on that. maybe there are some tests you can do with a DVOM multimeter, I have one of those, so if anyone has any good tests for the circuit using that I would appreciate it.


As for the blue smoke, we looked at some videos about the holes on the PCV valve on those engines being too small and they instructed them to be drilled out a bit larger, which made almost all the oil burning go away, but there is still some bluish smoke on acceleration. keep in mind that I have had this engine apart and the ring gap is PERFECT as per the Cadillac service manual... so I don't know what would be causing the remaining oil to be burning.

So the two problems I'm trying to solve are 1) the trouble code for camshaft sensor and 2) little oil burning/ blue smoke on acceleration.

Thanks for any information you may be able to give.
Finally, Sorry for the way too long and rambling post.... I just wanted to get as much info out there as possible. Shoot me your thoughts!
 

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Bank 1 is the side cylinder one is which normally is on left side

Read this closely as how P0366 is defined :

This P0366 code basically means that the powertrain control module (PCM) detected a problem with the "B" camshaft signal.
This DTC pertains to engine bank 1, which is the bank of cylinders that contains cylinder #1.
The camshaft position sensor (CPS) sends a specific signal to the PCM for Top Dead Center on the compression stroke as well as signals indicating the position of the cam sensor.

This is accomplished through a reluctor wheel attached to the camshaft that passes by the cam sensor.
Any time that the signal to the PCM is inconsistent with what the signal should be, this code is set.

NOTE:
this code can also be set by extended cranking periods.

The car will likely run with this code set, as it is often intermittent and also because the PCM can often operate the vehicle in "limp-in/limp-home" mode even with a cam sensor signal problem.

There may be no noticeable symptoms other than: Poor fuel economy (if engine runs) Possible no start condition Check engine light on

Other possible causes:

Faulty starter motor Starting system circuit Dead (Weak) battery can cause p0366 to trip as stutter on CAM

A code P0366 may mean that one or more of the following has happened:

Cam sensor wiring routed too close to spark plug wiring (causing interference) Poor wiring connection at cam sensor Poor wiring connection at PCM Bad cam sensor "B" on bank 1 Damaged reluctor wheel

Often replacing the sensor fixes this code, but not necessarily.

Therefore it's important to check the following:
Check that the wiring isn't routed too close to any secondary ignition components (coil, spark plug wires, etc.)

Visually inspect the wiring at the sensor for any burn marks, discoloration indicative of melting or chafing Visually inspect the cam sensor for damage
Visually inspect the reluctor wheel through the cam sensor port (if possible) for any missing teeth or any damage

If reluctor isn't visible from outside the engine, visual test can only be done by removing cam shaft or intake manifold (depending on engine design) If all checks out okay, then replace the sensor.

The Camshaft Position Sensor is an electronic device used in an engine to record the rate at which the camshaft is spinning. This information is used by the PCM to control ignition and fuel injection.
The camshaft position sensor senses the retraction of camshaft (intake) to identify a particular cylinder.

The camshaft position sensor senses the piston position. The sensor system consists of a rotating part, typically a disc, as well as a static part, the actual sensor.

When the engine is running, the high and low parts of the teeth cause the gap with the sensor to change
. The changing gap causes the magnetic field near the sensor to change. The change in the magnetic field causes the voltage from the sensor to change.

When the crankshaft position sensor (POS) system becomes inoperative, the camshaft position sensor provides various controls of engine parts instead, utilizing timing of cylinder identification signals.

The smoke could be CAM out of timing and getting some exhaust in cylinder and being re-burned ?
I see in cyberspace for this engine that sometimes there is a coolant leak causing it to leak down by PCM and
caking up the wiring pins that would need to be fully cleaned of the Male and female pins

We need a wiring diagram of the CAM sensors to pins of the PCM to check wiring and you need to see if the reluctor for that CAM sensor is damaged
 
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