This began as a timing chain issue now had the same P0017 codes with misfires on 1 and 5?

Tiny
AXLE67
  • MEMBER
  • 2010 GMC ACADIA
  • 3.6L
  • 6 CYL
  • 2WD
  • AUTOMATIC
  • 150,000 MILES
This vehicle belongs to a young lady that my wife and I have been helping for a number of years. We are giving her support to get her life together after being the child of an alcoholic mother. She likes to call us Mom and Dad.
I have a good deal of experience with cars coming from a family of automotive mechanics. I do all my own auto work, so when she told us her vehicle was kicking out engine codes for bad timing chains, she could not afford to pay for this repair. I told her that I would do the job.
I've rebuilt engines before, and this project did not scare me at all.
We made the two-hour drive in the car to get it back to our place. The car acted a little weak on power but ran fine without issue. I was surprised that the car ran as well as it did.
I ordered the timing chain set. I did not order new Phasers because the car ran well and did not kick out any code for bad phasers. Nor did I order a new oil pump because there was no indication of low oil pressure and the pump appeared in good shape.
When I did the tear down and notices a lot of build up inside the valve covers. The PCV circuit has not been working. This was my first time working on a direct injection engine, so I had to do a bit of research on this problem. So, I cleaned up the intake manifold and cleaned up all the valves and guides inside the intake rails. There was a considerable amount of buildup. I cleaned up the PCV circuit and the valve covers before installing the new style gaskets.
The timing chain installation went without any problems.
I followed a GM tutorial that I found online. The old chains were stretched a bit, but all the sprockets looked pretty good. The guides were worn down also. But nothing unusual otherwise. The kit included chains, guides and idler sprockets.
With what I have described, you would think that this was a slam dunk. This is where all the real problems began.
After getting everything back together, I began getting codes for a fuel pressure regulator. There is no fuel pressure regulator which leads me to the high-pressure fuel pump on the engine. A new pump didn't completely solve that problem. Now I began getting engine codes p0017 and p0019 along with misfires on 2, 4 and 6. Along with a fuel pressure code.
I added a can of Sea Foam to the crankcase and ran the engine for a while and then let it soak. I did this about four times. There was no improvement. I began looking at the wiring and found all these devices were powered by one circuit through a common relay. Switching that relay solved nothing. I tore open the wiring harness looking for a problem connected to that circuit. All six coils were connected together inside the harness. But nothing positive came from that work either.
Digging deeper, it now appeared that the cam phasers had now failed. The timing of this is bazaar. I've had the car now for six weeks and the frustration is indescribable.
So, I ordered a new set of cam phasers and four new cam sensors with four new cam solenoids and a new crank position sensor and a new fuel pressure sensor and then to top it all off. I installed a new $200 battery.
The only thing I have not replaced are the plugs and coils.
Remember, this car ran fine on the two-hour trip to get it to my house. None of this makes any sense.
The car now appeared to be repaired. My wife drove it to work and back with no issue. Later she ran a short errant and when she got back the car now had the same p0017 codes with misfires on 1 and 5.
My question of course is "how does a bad coil cause a pp0017? Even two bad coils should not cause this code.
A misfire should stand alone. It seems to me the misfires are a symptom not a cause. Earlier I had misfires on 2, 4 and 6 together. If I have this many bad coils, how is the engine even running? What is going on? I've read so many horror stories about this model vehicle, it's frightening. So many people have written posts about this same problem, but no one ever follows up to describe how it ended. From my experience, I believe they scrapped the car. This is insane. I worked for 40 years in the field of automation repair. Figuring these things out is my life's work. Nothing about this makes any sense. I've already replaced numerous parts that I knew were not the problem. All in an effort to simply eliminate the possibility.
My second question will sound stupid. Is there an issue with the dipstick on this vehicle? The oil level looks good on the dipstick. I put in five quarts. Do I need more? I've read a lot of comments about the oil level and keeping it topped off. Shouldn't the car run fine at any level as long as it shows oil on the dipstick?
Anyway, I'm running out of ideas and that just does not happen. I can't just keep throwing parts at this. I've got over $800.00 in parts already. Is it at all possible that I have an ECM failure?
I don't understand how this timing chain issue created this nightmare. Because I've heard this same story before from other owners. Some clarity would be appreciated.
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Wednesday, September 28th, 2022 AT 9:46 PM

13 Replies

Tiny
KEN L
  • ADMIN
First of all, nice work helping someone who needs it, that is what this site is all about. So, the problem sounds like the heavy build up inside the engine which plugs the oil pump pick up and the cam phaser control valve. The P0017 code indicates that the crankshaft and camshaft position sensor for bank 1 exhaust camshaft do not correlate. First, I would remove the camshaft actuator control valve and check for metal flakes and gunk which plugs the valve up, if found remove the others and clean them as well. Here is the location of the camshaft actuator oil control valves. Check out the images (below). Let us know what happens and please upload pictures or videos of the problem.
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Thursday, September 29th, 2022 AT 11:17 AM
Tiny
AXLE67
  • MEMBER
There is no heavy buildup. As I stated. I ran Sea Foam through the engine and let is soak for a couple days. When I drained the oil, I didn't see anything that unusual. The oil was dark but normal. I inspected the ports where the solenoids go, but they were relatively clean inside. Cleaner than I would have expected. Any buildup I have seen has been on the valve covers. All that was cleaned off on the bench. As expected, that is when I found the Bank one PCV valve was plugged. It's not even a valve, it's simple a port. There wasn't any evidence of build up or particles on the old solenoids. They were relatively clean. But I replaced them as a precaution, just to eliminate those parts.
I don't understand how the engine could run fine for one ten-mile trip, but then kick out a code later in the day, when my wife headed home. That's what doesn't add up. The confusing part is that this pattern repeats itself. It has done this same thing a couple days in a row. The code is not generated until she leaves work in the afternoon. Yeah, it makes little sense. Other than one possibility. Are the phasers not returning to a locked position?
If the phasers are in an advanced position, they would be misaligned with the crank. How is that possible? When the phaser solenoid opens, it should allow the oil to vent from the phaser with engine rotation. Could it be that this isn't venting the pressure and it keeps the cam advanced. This sounds familiar because I found two of the old phasers were in an advanced state but locked when I removed them and now appeared to be fine.
I think I can test out this theory by allowing the engine to idle for about ten seconds before shutting it off. Those phasers should return to their locked position.
I have considered the theory with plugged oil passages or debris. I just can't find any evidence of that. Furthermore, why would the engine run fine on the first trip, but not the return trip? This has been the pattern of behavior when these codes show up. Any other thoughts?
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Saturday, October 1st, 2022 AT 5:27 AM
Tiny
KEN L
  • ADMIN
When you replaced the sensor did you use AC Delco parts? You may have a defective sensor. You could have a plugged oil pump pick up from the gunk getting flushed into the oil pan?
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Saturday, October 1st, 2022 AT 12:22 PM
Tiny
AXLE67
  • MEMBER
You can't be serious. You're suggesting that gunk in the oil pan is interfering with oil pickup. So, this gunk sits casually in the bottom of the oil pan for the ten-mile drive to work and then magically reappears on the trip home. Wouldn't that cause a more random symptom?
That would have to be some kind of epically big chunk of gunk. Would that not generate and poor oil pressure response? Which is something I have not seen.

The idea that a new part that is not AC Delco is inadequate, is a bit bias. AC Delco parts are just more expensive. Most of these parts come from the same sources.
I would also like to know the odds of these new parts causing the exact same symptoms as the old parts. In the exact same pattern.
Logic would suggest that the these new parts have nothing to do with the cause of this problem. I replaced the parts, hoping for a change in symptoms.

I appreciate solid well thought out advice or suggestions. I don't have any patience for this.
If you don't have any idea, just say so. I wouldn't ask if I wasn't running out of ideas myself, but I still have a few that are better than this.

Perhaps you did not pay close enough attention to the details I've documented. You made no comment about my observation is regard to the fact that it appears that the cam phasers are not returning to their locked position. There is evidence with this theory with the pattern of failure and with the old phasers I removed.
Isn't it more likely that the ECM is the more likely cause than a huge chunk of gunk at the oil pickup?
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Sunday, October 2nd, 2022 AT 5:13 AM
Tiny
AXLE67
  • MEMBER
I thought I would send an update on current symptoms. It is only on Bank one. Bank two seems to be fine.
I still do not understand why the Cam phaser are not returning to their "home" and locked position. Right now it appears that only Bank one that has this problem. The car has stopped kicking out misfire codes. A week ago it was getting misfires on cylinders one and three along with the P0017. Now it is just the P0017 code alone.
I have instructed my wife to allow the car to come to a steady idle before shutting off. Giving the cam phasers time to lock. It seems to have helped. But the problem persists.
There is little logic to explain why the engine only generates the codes on her trip home and not the morning trip to work. I believe the code is being set when she pulls to stop at traffic lights and the phaser don't get time to lock at idle. Why it does not do this in the morning is troubling. The only thing I think is that she leaves very early in the morning when there is little traffic and may not have to stop. Traffic is heavier in the afternoon and stop and go.
I understand your logic with plugged oil passages. I just have trouble with that theory based on inspection when I had the front cover off. I looked inside those ports when I had the solenoids out and they were clean. A little normal discoloration, but no build up at all.
The circuit for the solenoids is a simple circuit The solenoid only opens to allow oil pressure in. When it closed it dumps the back pressure from the phaser, to the crank case.
That is the way I understand this circuit to work. The valve only pressurizes the phaser to advance the timing. There is not a return or opposing circuit. Cam rotation returns the phaser to the locked position after the oil pressure is vented. Did I miss something.
I would think that this system would need to work pretty hard to advance the cams. I would think that simple engine rotation would be a constant opposing force, that would always move the phaser back to locked.
This is why I suspect the ECM. The ECM must fire constant signal adjustments to the phaser solenoids to modify the timing advance. When the signal drops, the phaser should naturally move back toward the locked position which retards the timing.
I would think that any issue with the wiring, like a bad connection would manifest itself by not advancing the timing. If the cam phaser is not being allowed to return back home to a locked position, the ECM would need to send a signal to keep the cam from retarding. I don't know how that is possible without the ECM making miscalculations and sending out incorrect timing advance signals. The ECM has a profile it follows to engine timing at given RPM speeds. Could an ECM send out an erroneous pulse that is outside that profile?
Is there a document that graphs the factory timing advance profile?
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Friday, October 7th, 2022 AT 5:12 AM
Tiny
AXLE67
  • MEMBER
It's Sunday and I thought I would go back and review this exchange. I wanted to apologize for being so direct and short in my Oct. 2nd response. I stated that I have little patience for weak ideas, and that was a bit rude. In my defense, I admit that my limits are being tested by this problem. This timing chain issue has consumed my summer. What should have been a two week job at most has turned into an eight week nightmare. It has tied up my
garage and I have been unable to work on any other projects. This has been Karma's way of letting no good deed go unpunished.
Something that is nagging at me is the disconnection between the original problem of
worn stretched timing chains and this nightmare. How does the act of physically replacing the timing chains develop into an issue with Cam to Crankshaft timing, when this problem did not exist with the stretched timing chains. Not one post has addressed this phenomenon.
I have replaced the timing chains and sprockets. I have replaced the Cam phasers. I have installed new Cam advance solenoids and all four Cam sensors. I even installed a new Crank position sensor. I installed a new high pressure fuel pump and a new fuel pressure sensor regulator. Then to top it off, I put in a new battery because the old one was weak. I have gone through the circuits and inspected the wire harness for shorts or breaks. I have disassembled the fuse box to look for poor connections to the transfer relay that powers all these devices. I found a few breaks in the insulation of some wires and I have corrected any potential issues with those minor problems.
One problem I do have, is I have no one to share my thought with. I'm pretty much on my own. It really helps to hear how other technicians interpret problems. We do not all analyze problems the same way. I tend to work more through the process of elimination.
Eliminate one possibility and what remains must be where the problem is until I am able to corner the cause. But of course there are times when the problem is obvious and this logical progression isn't needed.
Now just for the sake of argument. Let's say that we have a problem with "gunk" or plugged oil passages. Why did that issue only become apparent after replacing the timing chains, and why was that not a problem before? It does appear that there was a problem with the PCV circuit and the crankcase was not venting properly. I don't believe the entire PCV circuit was compromised. Bank two did seem to still be open. There was some build up inside the valve covers. But I have seem far worse. The build up was mostly on the inside of the valve covers and not on the valve train.
So I have to ask the question. What changed? There is no logical explanation for this being the cause, when this wasn't a problem prior to replacing the chains. Where is the logic in this analysis. Don't think that I haven't entertained this as the cause. I haven't been able to prove it or discover any further evidence of this. As I stated previously. The solenoids were pretty clean when I removed them the first time. These components has the normal amount of tarnish and discoloration, but there was no evidence of build up. But I replaced them all the same. So how is it possible for the Cam phaser to remain advanced when the engine is at idle. How is it theoretically possible for the oil vent circuit on the Cam solenoid to become plugged when it is an active circuit and this car is a daily driver. Let's remember that this was not an issue driving the car prior to the teardown.
I have a theory and it's kind of crazy. At this point, it's the only thing I believe that makes any sense.
I value your opinion, even though it may not appear that way at times. You have daily experience with these problems and that is valuable. My background is in the field of
automation and numerical controls. Working with automated industrial equipment and the their PLC controls. The ECM in today's car is nothing more than a PLC with a more innocuous name. What I lack is the day to day exposure to these automotive problems and the experience from that exposure. It's pretty obvious that there are things that auto industry does not want to share. I've eliminated everything else. This is what's left.
The ECM. What I would love to see, is the ladder logic to this vehicles ECM. Much like a PLC, it can be programed to track many operations and modify the behavior of the control to change to way a machine performs. This is how the manufacturer can put a vehicle into
"Limp Mode". By monitoring inputs and changing the operation profile. Something in my gut tells me that GMC has programed a response into the ECM that is creating this behavior. Forcing customers into their service centers. Let's be honest. This is where car manufacturers make their money. Parts and service.
My next most logical step will be to either purchase a replacement ECM or have this one reprogrammed. I believe putting the ECM back to it's original factory settings will make this problem go away. What do you think. I did say it sounds crazy. But it really doesn't sound that crazy when you stop to consider how vehicle technology has changed. As technology continues, fewer and fewer people are able to "do it themselves'. Many of these repairs now require specialized tools to service these components or remove them.

DJ.
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Sunday, October 9th, 2022 AT 8:50 AM
Tiny
KEN L
  • ADMIN
There are many grades of parts out there and it can be frustrating trying to repair a car when the parts are not working as intended, but I get what you are saying, also gunk in the pan cause strange problems that can show up at any time, but I see your point as well. When you said, "When I did the tear down and notices a lot of build up inside the valve covers." I assumed there was build up in the pan as well.

Also, "the cam phasers are not returning to their locked position" is the reason I suggested the camshaft oil control valve might be ticking open allowing oil pressure to keep the phaser activated. I cannot see the engine or check things myself so there is a slight disconnect over the internet, I apologize if I upset you in anyway. So, let's get this vehicle fixed. :)

The fact that the problem of the P0017 stands for Camshaft Position B Camshaft Position Correlation (Bank 1) problem, so the crankshaft is not aligned with the camshaft B. is there a chance the timing marks are just off a tooth?

The actuator returns to the neutral or standard position when the oil control valve exhausts the oil inside the phaser. Here is guide that shows how it works to help and I have included the timing marks for the chains and camshaft phasers to help you double check your work.

https://www.2carpros.com/articles/how-camshaft-variable-valve-timing-works

The marks are correct then something must have come apart or got stuck in the phaser not allowing it to return fully. Check out the images (below). Please let us know what you find. No worries about the frustration, no one is happy when they are having car repair troubles.
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Monday, October 10th, 2022 AT 10:36 AM
Tiny
AXLE67
  • MEMBER
When I had the opportunity and had some access to the oil pan. I made efforts to clean out the oil pan both times I had access.
I am familiar with many of these illustrations. When I researched this project. I looked a multiply sources and did not just trust one single source. I used a GM tutorial that was posted on YouTube. I followed that sequence very closely, noting and identifying each unique alignment mark and position. After taking this apart a second time to install the new cam phasers. I made no mistake and triple checked my work. It is impossible for the cams to be out of alignment when this procedure is followed correctly. There are flats on each cam that need to be in position when the chains and timing marks are aligned. The phaser comes locked and cannot be moved without oil pressure.
You stated, "The actuator returns to the neutral or standard position when the oil control valve exhausts the oil inside the phaser". You suggested that there could be something inside the phaser that is preventing it from returning. Yes, that is a possible, but not probable This seems highly unlikely for the new phasers to suffer the same problem as the old phasers suffered. Remember, I mentioned that the old phasers were not returning to the locked position either. But when I removed the old phaser, it returned to the locked position when I was removing it. The old phaser was not being prevented from returning home due to any foreign object. It was oil pressure, and that pressure is always commanded. The phaser was advanced when the engine was shut off.
After all the considerations, I conclude that the cams are being commanded to stay advanced.
The ECM may not be allowing the phaser to vent, and the ECM is modulating the pressure to the phaser. If the engine is still rotating and the voltage to the solenoid is cut off. There is no way that phaser should remain advanced.
Tomorrow, I plan to take the vehicle over to a shop nearby and have the ECM flashed back to factory setting. Other vehicle owners, who have had similar issues have made mention of flashing the ECM. Normally, disconnecting the battery does this. But I'm not convinced that this works all the time. I have to eliminate this as a possibility. After that, if the problem doesn't go away. I don't believe any options remain. There is nothing left. There are only a few components that I have not replaced. I don't see how a spark plug or coil would cause this problem.
I will update you when I have more to report. Feel free to share any other ideas.

Dj
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Tuesday, October 11th, 2022 AT 8:58 AM
Tiny
KEN L
  • ADMIN
I was going to say the ECM could give faulty commands as well. Also, can you check the oil seals on the camshaft actuator in case the oil is bypassing the valve? A nick or crack in the head? Also, if you remove the actuator to phaser you should return to the neutral position once the engine is cranked over and (not started). Watch out for oil to be pushed out of the port. I want to know what's going on, this is not an everyday problem for sure.
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Tuesday, October 11th, 2022 AT 1:14 PM
Tiny
AXLE67
  • MEMBER
I thought this through also and came to the conclusion that any leak or blow by on the solenoid would only disrupt the cam advancing. It would not prevent the back pressure from venting. I also concluded that this would only prove what I already know. The cam phasers are not being allowed to return to neutral or a locked position.
I stopped at the service center which had said that they do this "flash" work. Apparently, that guys who did that are no longer there. I have been waiting for a call back from someone that does this work exclusively. Until then, I have another car in the garage and can't do anything with this one for a few days. Somehow, I doubt that the ECM would even allow me to crank the engine over without seeing those solenoids hooked up. I'm not too keen on the idea of cranking the engine with the engine mount removed. You need too remove that engine mount to access those solenoids and sensors. I would not be able to see anything with that engine mount in place and something in my gut tells me that this attempt would not go unpunished.
While talking with this service tech, he said something about performing a Crank Position Relearn. I've done that on my truck after replacing the ECM.
I have an analyzer that is specifically designed for GM vehicles and I can watch the engine in real time. I used this on my truck to perform this Crank position relearn, but this unit doesn't offer that diagnostic for this model car. So that was a dead end.
I can watch each cam and cam solenoid for outputs. The unit tells me what should be commanded and what is currently happening. I can clear all the error codes and start the car and just allow it to idle. The car will run beautifully and not put out any codes. At idle the intact cams both show some kind of activity that I don't think should be there. The codes are not set until I shut the car off and restart the engine. Then I get this P0017 code. I should not be getting a cam advance at idle. But the cam is advanced when I shut the engine off after only sitting at idle.
If this guy does not call me back today. I'm going to order a preprogrammed ECM for this car. Eliminating the original ECM altogether. It's another couple hundred bucks, but I don't know what else to try at this point. Paying a shop to hook up to this car could cost hundreds and that's just not money I have. Then to only find out that they think a new ECM is the solution. Now days, shot gunning a project makes more sense. Put the money into parts rather then paying someone else to make a guess.
It's going to be a few days before I know anything more. Thanks.
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Friday, October 14th, 2022 AT 11:50 AM
Tiny
KEN L
  • ADMIN
I would try the crankshaft position relearn and if that doesn't work the PCM will be the next choice. I know it didn't have the problem when you took it apart but maybe it had a voltage surge when the battery was reconnected. There is no chance the actuator has metal in it keeping it from returning completely. And no questions on the chain timing? Let me know please.
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Saturday, October 15th, 2022 AT 12:11 PM
Tiny
AXLE67
  • MEMBER
Ken,

I wanted to send you an update on this issue. I ordered a new ECM and installed it last Saturday. I had to go through the process to relearn the security key, and that all went just fine. I started the car, and it seems to have solved this problem. Over the next three days, I would start the car and let it idle and then shut it off. Normally, this would generate the P00017 errors along with a host of others. For those three days, this never happened. So, we made arrangements to get the car back to the owner.
We were three blocks from our home when the engine light came on. You can imagine my reaction. I turned around and went back to get my analyzer. Same problems.
I could see that there were a number of codes and then suddenly they were no longer there.
I didn't clear them, but they were now gone. But the engine light remains on, and I can't seem to clear it.
The only other thing that I can think of, is returning to this question about the Crank Shaft position relearn. Maybe, just maybe this system is so stupid that it can't figure this out on its own. The crank has a segmented ring that sends this signal. How can that be misread?
I'm at my wits end with this. I have, against my better judgement, decided to return the car to her with instructions on how to deal with this issue. I suggested that she get this thing out of her life and find something else.
Just based on my experience with this Arcadia. I will never buy a GMC. I've never seen anything like this before and you wouldn't think I could say that because I own seven Jaguars and have seen some crazy.
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Thursday, November 3rd, 2022 AT 10:16 AM
Tiny
KEN L
  • ADMIN
Yep, that is a good one alright, you would think it would self-learn but the crankshaft sensor must go through the process to work correctly.
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Thursday, November 3rd, 2022 AT 1:48 PM

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