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Discussion Starter #1
Hi, I just bought the 2010 Malibu LS 2.4 Flex fuel. and I found engine oil was OVER Filled by the mechanic. I had to pump out 1.5 liters. and still, it was on Max line. (I guess, the mechanic was confused with V6 engine) and I changed the engine oil with Full synthetic oil again. and I found check engine light was on before. and it shows P0016. so I changed the Camshaft sensor and Crankshaft sensor too. I've tested the Camshaft sensors with power on and generates 5 volts when I put the metal to the sensor and goes down to 0.6 volts or so when I remove the metal from the sensor. But that P0016 code doesn't go away. even after I erased the code by OBD2 code reader. and disconnect the Negative battery connector around 1 hour while I was changing the Crankshaft sensor. but still, code didn't go away. and I did clean the most of Ground wires and apply the dielectric grease too. but still code didn't want to go away. ;(
Now, my symptom of the car problem is;

1. When I start the engine, Engine idle fluctuated approximately 5 seconds or so. then, it stabilizes by itself and has no problem at all. Even passing the other car is not a problem at all. It has all the power I need. But check engine light (P0016) still remains.
2. Once the engine is warmed up, the engine runs very smooth. but if I start the engine again, Engine idle fluctuated approximately 3 seconds or so. then, it stays very nice and gentle idle afterward.
3. I've checked both Solenoid valves and it is very clean too. No particles at all.
4. On idle, I could hear a bit of muffler leaking sounds like from the bottom side of the engine but if I give throtle it goes away.
5. P0016 code keep coming back.

I've checked most of the connectors and applied dielectric grease too. so as to the ground wires to the engine and chassis.
and I've clean the Throttle body too.

What would it be the trouble here?
Would it be ECM (Engine control module) trouble?

Does anyone have similar trouble like this?
Please, Let me know what you think.
and Thanks a million in advance.

Joe.
 

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P0016 CHEVROLET Tech Notes
If this DTC started after recent internal engine repairs, inspect for proper engine mechanical timing. With the camshaft cover removed and the #1 cylinder at top dead center, make sure that the darkened chain links are lined up with the alignment marks on the exhaust and intake cam sprockets.

If a P0016 is resetting without any engine performance concerns but the above information did not isolate a cause for the DTC, replace the Cam Phaser Actuator sprocket.

There is a factory service bulletin for the following Chevrolet models:
2008-2012 Chevrolet Captiva
2008-2012 Chevrolet Equinox
2008-2012 Chevrolet Malibu
2009-2012 Chevrolet Traverse
2010-2012 Chevrolet Camaro
2012 Chevrolet Impala
Chevrolet Factory Service Bulletin OBDII Code P0016
 

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Discussion Starter #3
I just checked Camshaft position solenoid too. but both of them are good. I got 19 ohms on each of them and very clean. so I guess it is the Timing chain problem, then. It might be over my ability. so I might have to call the dealer to repair. Would you have any idea how much it would be? Thank you so much for your valuable info. Joe.
 

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Discussion Starter #4
Actually one more question. Although I got the P0016 code, the only problem I get is a rough idle at the start. but after 5 seconds or so, it goes steady and there is no problem at all. it has all the power to pass the other cars and so on. Would it be still a timing chain?
 

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I just checked Camshaft position solenoid too. but both of them are good. I got 19 ohms on each of them and very clean. so I guess it is the Timing chain problem, then. It might be over my ability. so I might have to call the dealer to repair. Would you have any idea how much it would be? Thank you so much for your valuable info. Joe.
I never had my timing chain replaced, but I believe they have to pull the engine. I would guess somewhere around 2k to replace.
 

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Like the tech tip says it might just be the actuator sprocket but that's timing chain surgery. Get a estimate and see if car is worth the repair. Since you just bought it you really do not know what or who as done to it.
 

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Discussion Starter #7 (Edited)
When I replacing the Camshaft position sensor, I found a lot of black sludges and I picked out a lot inside of the hole. so I took valve cover out today and found a big mess in there. so I've cleaned all that black stuff from the camshaft position sensor area. (You could see a half Black and a half white area that I cleaned.) It didn't want to be cleaned. so I had to use the solvent on the toothbrush and spent a half-day to clean them. But I found the Timing chain was pretty tight and shiny. The only thing I couldn't do (didn't want to do) was re-aligning the timing chain. Well, I tried to line up those marks on the chain and sprocket's mark. but it was impossible to move that chain. (I was trying to line up with starter motor but I keep missing them. I didn't want to open the sidewall of the engine. (Lazy and Scary.) and after all that hard work(?), the only thing that shines is the check engine light. I don't know if I should drive for a while to re-train the engine or not. But I have to learn more about the Timing chain align and challenge later again. ;) Thank you all for your valuable advice.

Another question is, Why and How is that sludges buildup and burnt marks???
 

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Sludge and build-up are from cheap oil and/or oil change intervals that have gone too many miles.

That mess could also be from how the vehicle is used, such as being started cold, driven a short distance, and then shut off. Short trips like that are cancer to an engine.

I'll go out on a limb here and state the obvious, and please pardon my being frank:
If you're not sure how to time the engine, stop now and get someone who can. You could easily damage it badly enough that you'll need to replace some very expensive parts and maybe even the entire engine.

There is no "re-training" the engine to somehow know where the timing chain and valves are located. In this regard it is 100% mechanical. The crankshaft and camshafts must be aligned to each other perfectly and this is done with the timing chain before the engine is turned (by hand or by starter).
 

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Discussion Starter #9
Yes, that's why I stopped. ;) Since the timing chain is tight and looks healthy shiny and the engine running perfect and no hesitant at all, I assume the timing chain is good. (either manufacture setting or someone changed recently) and it has a VVT camshaft, I start thinking Camshaft position actuator solenoid valves. ;) Because my son had one time too much oil in his Cobalt and blow the solenoid valve. and this Malibu had too much oil in it. (1.5 liters pumped out and it still on MAX line on dipstick) It might damage the solenoid valve too, I HOPE. ;) I just ordered a set of solenoid valves. so I will know when I get those. and I will post the result too. ;) Thank you so much for your frank advice.
 

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Did you use OEM parts for the solenoid actuator or did you buy the cheap $10-20 parts off the internet? The cheap parts wont clear the code.
 

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How any miles on your car? Given the age, you should be at least at 100K by now. The chain (with good maintenance) will easily last that long. From the photo, your chain idler plate looks good (not missing the plastic/Teflon guide). Check the slack in the upper top (between intake and exhaust cams) to make sure you have less than 1/8 inch of slack. Also check the chain side of the idler plate for excessive wear. FYI, the TSB that was attached addresses the V6 engines.

The sludge is not a good thing, that in itself could keep the solenoid from applying the proper correction to keep from throwing the P0016 code (might be worth running a cleaner in the oil to clean up the sludge and changing the oil again). A jumped timing chain would produce poor engine performance, so you probably did not have that occur.

I would give the electrical connections (especially the actuator connector socket contacts on the wiring harness -- not on the actuator itself) to make sure there is no corrosion (not just the contact area). This area of the engine gets warm, and you could have a hidden wiring issue (though it sounds like the ECM is getting some timing correction based on the improved idle.

If it was my car -- I would check the connections again first (free), the chain slack (free), then run a cleaner (Seafoam) to get the sludge out (including removing the actuator again to see if there is more sludge from a clogged oil passage).

If you are over 200K, then it is worth looking at the chain in finer detail.
 

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Discussion Starter #12
I just installed "Timing chain tensioner" and it went in okay but still P0016 is remains and idle is fluctuating for 5 seconds or so and then, the engine goes smooth after that 5 seconds. and it runs good and no hesitation. I don't know why it does that. I guess have to reset the timing chain or what?!

I've cleaned sludge out (wasn't much in there though) and try to clean the carbon buildup inside of the Valve cover area as much as I can. and changed engine oil with Full synthetic. and I noticed it had a brand new GM oil filter was in it. but I changed the filter too. but again, I had to take 1.5 liters out. Too much oil was in it. and I've changed, Camshaft position sensors, crankshaft position sensor, intake, and exhaust solenoid valves, Finally timing chain tensioner.

2010 Malibu 2.4 LS Flex fuel engine. 96,000 KM on it. (59,651 miles). and the chain looks clean, chain guides look good. but I couldn't check the timing chain aligning. and I don't know how strong tensioner should be. but pushing rod was a bit easy to push it in.

Also, I've applied dielectric grease on the most connectors and the grounds that I could find in the engine bay. and when I took out the solenoid sockets, my OBD2 code reader shows both codes and put it back in, it clears out by itself.
and both old solenoids were all clean. no sludges or any kinds of the particles at all. but I've changed them all.

So, now I'm kind of run out of the options.
 

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Discussion Starter #13
Probably the last question here. ;) Is there any way to turn the "Crankshaft" with a breaker bar without opening Side cover of the engine? Other words, without taking a serpentine belt or anything. Just try to check the Timing chain alignment. I tried to turn it with the starter motor but I couldn't perfectly align them. And just in case, if I have to take the side cover of the engine, Do I have to drain the engine oil first?
 

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Discussion Starter #15
Ah~~~, that will do? Awesome. What about the engine oil? Do I have to drain first if I want to open the side cover? and Thanks a million for your precious advice. ;)
 

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Discussion Starter #17
Okay. this is my theory. since the timing chain is still good and engine performance is good. I'm just thinking that "Timing chain Tensioner" was weak and "Exhaust camshaft sprocket" got jumped. ('cause, Exh. sprocket has the "Spring" inside) So, if I align the chain with "Intake camshaft sprocket" and re-adjust the "Exh. sprocket" at 1st cylinder dead center would fix my problem. or vice versa?! I will try that maybe Monday afternoon or so. and I will post the result. Thank you all for your precious advice.
 

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Again, does your chain have any slack (you should not be able to deflect the chain more than 1/8 inch).

If no (and given the miieage and lack of performance issues), it is unlikely the chain jumped.
 

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Discussion Starter #19
Thank you. I will try to check the Timing chain on Mon or Tuesday and I will let you know. and you are an awesome man. ;)
 

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The timing chain guide/tensioner is there to keep your chain from jumping a tooth. Was the guide worn down when you removed it?

60k miles is early for a chain failure. It is also low mileage for the age of your vehicle.

Any chance the mileage is not accurate?

The interesting item is that your idle cleans up after a few seconds. If I recall correctly, the timing should be set for idle, then optimized wat higher rpm (via the solenoid valves).

A poor idle is common with a jumped chain, though the age suggests otherwise.

If you have chain slack and a worn tensioner, then your mileage may be funny. Check other wear items (break pedal) to see if the wear is consistent with the mileage.
 
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