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Discussion Starter · #1 ·
Just two weeks ago I was having more issues with cold starts, car sounded like it was trying to murder itself while cold, but started behaving once warm, had a few hard shifts, yet it refused to throw codes, finally, on a day off it threw codes, and it threw a lot of them. The codes in question were P2544, P2101, P2100, P0638, and finally P0700.

After getting the codes, me and one of the techs in the Auto hobby shop cycled through a multitude of options, checked vacuum, tested coolant, before finally I stopped, stared at it a minute and thought about my previous issues with the throttle position sensor, so we went ahead and tested it, and it was having a **** fit as far as power goes, but, sadly, no Tech2 on hand...so I was forced to take it to a stealership, which, it could've been worse, they charged me 275$ for the part, and replacement.

Once that was said and done, it lasted a week before throwing yet another code. P0391, which we tracked down to being the camshaft position sensor Bank 2 exhaust side. Parked the G8 for now, and finally said to hell with it and I'm shipping my Tech2 from Missouri since it refuses to not kill sensors. Guess the good old Elco is getting daily driven for a few days again lol
 

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Discussion Starter · #2 ·
Update: Got the Tech 2 from home, gonna deal with the Sensor tomorrow, fun times ahead! For once it's a simple job.
 

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So replacing the throttle position sensor on the V6 requires reprogramming the throttle body via a Tech II? Think the V6 has a throttle relearn procedure, if so it may not be applicable in this case.
 

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Discussion Starter · #4 ·
It requires reprogramming the ECM to the throttle body, whether that is possible without a tech 2 or not, I'm un-aware, only that they didn't have a OBD-2 device on hand capable of doing the relearn procedure, and I couldn't for the life of me find the relearn procedure anywhere that didn't include using a OBD-2 tool or Tech 2.
 

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Discussion Starter · #5 ·
Update 2 and final for sensors: Camshaft position sensor replaced, and cleared codes, watched the counts for the sensors and everything seems to be back to normal, gave it a quick drive to test and it seemed to run much smoother than before, here's to hoping I don't throw that code again!
 

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Sounds great. Curious, was a genuine AcDelco camshaft position sensor installed or an aftermarket?
 

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Discussion Starter · #7 ·
The failed one was an ACDelco.

It turns out the sensor may not've been the culprit, turned the car on put it in gear and another code was thrown, same one, P0391. Going to take pictures of the failure record data now, sitting in the car with it up.
 

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Have the same intermittent check engine code and it seems to come on and go off after a few start cycles. Have checked and verified the oil level. Ran crankcase cleaner through the engine. Replaced all four camshaft position sensors. Replaced the crankshaft position sensor. Awhile ago, the timing chains were replaced when the car was still under the power-train warranty. Per my understanding, the variable valve timing solenoids wouldn't produce a P0391 code. Am leaning towards it being starter related, but can't say for certain. The battery is nor was the culprit. Bear in mind, the crankshaft position sensor was replaced specifically in an inexpensive attempt to address the P0391 code. The other things were done to remedy/troubleshoot other problems. At this juncture, am not overly concerned with the intermittent P0391 code, but will continue to monitor/assess the situation.
 

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I read that this code is saying that your bank 2 exhaust cam position sensor has a performance problem (maybe intermittently), but at least long enough time wise to set the code. When it does that, it says it defaults the exhaust cam to the zero degree position. An the same time it says that it commands the bank 1 exhaust cam to the zero degree position (I guess to keep both banks balanced power wise as possible). I can't tell if both intake cams are allowed to continue to set whatever advance or retard setting that the ECM is requesting, if at the same time the ECM has forced both exhaust cam actuators to the zero degree setting. Are you sure that the 3 wires to that #2 exhaust cam sensor are in good condition ? If any one or more wires goes south on you (whether intermittent or continuously), I think that would cause the ECM to loose the pulse count it must see continuously from that actuator.
 

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Good point about the wires, they have a tendency to rub against the plastic engine covers.
I had this problem on my V6 on the right side of the engine where the plastic was completely worn of a few wires.
Got a can of Blue Magic Electrical Tape liquid sealant to cover the bare wires.
Come to think of it I should really check those again....
 

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Can recheck the wires and wiring harness, but at last check everything was intact except for the connector on a variable valve timing solenoid.
 

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Discussion Starter · #13 ·
Update on the sensor issues. I went into the auto hobby shop and took a multimeter to it, voltages were good, and I checked the counts with a Tech 2, turns out all the others were reading 241, and this one sensor was reading 56, it was completely out of sync with the other sensors. There's a potential that this new sensor may be bad as well, does anyone know of a procedure to set them all at the same number?
 

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Wow!!!! What a nightmare >>>>>> Each cylinder head contains 2 camshaft position sensors an 2 camshaft position "actuator" sensors. Position sensors use 2 wire circuit, whereas the "actuator' position sensors use a 3 wire circuit. One type of sensor has the attaching bolt inline with the connector (position sensor ? ), whereas the the other has a 90 deg offset attaching bolt (actuator position sensor ? ). I've read thru the manual a couple of times, and find myself getting more confused each time as to which one of the 2 exhaust sensors might/could be acting up. I sure hope the difference between the 2 sensors make since to you.
 

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I've read threads about like situations.
May mean nothing but stick to same brand of sensor that came out of the car don't go after market.
Mixing sensors seems to make these cars loose they're minds.
If you took out a Bosch replace with a Bosch.
My 2 cents FWIW.
 

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Discussion Starter · #16 ·
Next, and hopefully last update: I went ahead and bought another sensor, Bosch specifically cause I remember seeing that on the last one, just for the hell of it, hooked up the Tech2 cleared codes and watched the counts when I started it up and the counts all sync'd up correctly with the new sensor in place, I drove it around a bit and any roughness that I had felt before has all but vanished, I drove it around a bit and didn't feel anything wrong with it, here's to hoping it stays that way!
 

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Discussion Starter · #18 ·
Sad morning update: The CEL popped instantly on startup in the morning, the counts are off once more, but it seems to only be the case on a cold start, and the CEL cleared itself after it was warmed up and turned off and on and driven a few miles, it seems the issue persists only when the engine is cold, still unsure of the cause as I've checked the power when off and on, cold and warm and the power going to the sensor is good, I suspect a potential spacing issue between the sensor and the reluctor wheel, but I am unaware of any spacing procedures, the only other issues I can think of is an ECM issue or Oil, however the oil is right on the full mark, and is currently at 500-600 miles on the current change of oil, will update further when I have more information, I swear the ECM is asking to get swapped with an aftermarket one if it is the culprit.
 

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Stupid question but is the oil a quality synthetic, Mobil, Castrol or Pennzoil, and an AC Delco filter.
There are threads on here of owners who have had problems after oil changes.
I know I sound like a nut bar with the same brand part on as off thing but these cars seem to know when you've used a after market brand of part.
 

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Discussion Starter · #20 ·
I've used Royal Purple and wix filters every 3-4k miles for the past 10k~ and trust me, I get it, GM engines are fickle things when it comes to sensors. I've been thinking the same thing, however.
 
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