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No end of troubles from my 2008 Nissan Sentra

I am hoping to get some new opinions on this. I bought the car in January with 85,860 miles on it. After a few days, I noticed that the RPMs would jump up and fluctuate a bit the first time I would start it in the morning. Within a week of buying it, it would no longer start. The mechanic I took it to replace a cam shaft position sensor and the battery. Flash forward to early August and it has about 100,000 miles on it. The car has started doing the same thing when I start it in the morning. This time, the car breaks down in the mountains miles from anywhere. Luckily, someone went and got the park rangers for us. A second mechanic replaces a cam shaft position sensor (not sure if it is the same one as before) and the timing chain. When I pick the car up, the service engine soon light is on, but I assume that they forgot to reset it. A few days after that, the car starts having issues starting. I take it to a third mechanic who says there is an issue with the timing chain that the last guy installed. I call the other mechanic and they ask what the codes are and if the third mechanic reset them to see if they came back on. I don’t know, so I try to take it to an auto parts store to have them look, but the car won’t start. Turns out the battery is bad (the 7 month old battery), so I replace it. Seems fine at first except I notice at idle that the engine will sometimes shudder. A few days later, waiting at a red light, the engine shudders and dies. We restart the car and everything seems fine. Meanwhile, I take it to four auto shops in two states and no one will reset my check engine light because it is apparently illegal to do so. I do get a list of the codes though (P0340 Camshaft Position Sensor, P0011 Intake Valve Timing Control Performance, and P0011 again). Yesterday, while coasting down two hills, the RPMs jump up higher than usual (up around 2000) and there’s a feeling from the car that I can’t really explain (maybe feels like going down a hill in low gear?). Later, as I am sitting at a red light, the RPMs start rapidly fluctuating but very slightly and the engine dies. I restart and it seems fine for about 10 seconds. As I am driving the RPMs start doing the rapid slight fluctuation again. Both times it feels like the car is jerking forwards and backwards. Luckily, I was able to get it home. Any ideas? As it is, I need to call both mechanics back, but would really appreciate any opinions. Sorry for the huge post, but I feel it’s necessary to share what this car is putting me through.

Here’s what’s causing the P0011 DTC.

At this point, I would change the oil and filter, and add SeaFoam to the oil.

The cam phaser may be sticking from gum and varnish.


I wouldn’t drive it much farther than 200 miles or so if the Seafoam clears this up before changing the oil. It may break loose lots of gunk all at once and you don’t want that all in the oil.

Thanks for the info. I took it to a new mechanic who said that the cam shaft position sensor needed to be replaced and that the timing chain was off by a tooth. He said that the issue may be that parts other than genuine Nissan parts don’t last as long in these (a different mechanic had previously told me that Nissan timing was trickier than normal). They won’t do the work unless it means replacing everything the previous guy did (cam shaft position sensor, timing chain, and kit). So, it’s back to talking to the previous guy because he said that if it was related to what they did they would make it right. Current issue is trying to get the previous guy to return my phone calls. So, does this track with you all or does the explanation sound far fetched?

I have to disagree with the new guy that parts other than genuine Nissan won’t last as long. Not true.

I wonder if the new guy realizes that the “genuine” Nissan parts are not actually manufactured by Nissan. They’re one of many parts subbed out to an aftermarket manufacturer. All car manufacturers do this.

How did he determine the chain is off a tooth? Did he actually tear into things to verify this or is was this more WAGing?

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I presume your engine has variable valve timing, right? Just a guess, but the reason you may have to keep replacing the camshaft sensor is that it is getting damaged by some untoward action of the variable valve timing (VVT) function. By that I mean VVT isn’t working smoothly like it should. And the resulting jerking of the camshaft is damaging the sensor, and possibly other stuff in the timing chain routing, including the chain. Like I say, just a guess, but if I’m correct you need to get the shop to focus on why the VVT isn’t working smoothly. And of course get the base-line valve timing aligned correctly.

Unlike cars without VVT, where there’s some lee-way, the VVT function is super-sensitive to the engine oil specs and to the oil change intervals. So going forward, suggest to make sure to use the exact oil spec recommend by Nissan, and use a Nissan oil filter you buy at a dealership, and change those both at the Nissan recommended intervals as a course of routine maintenance. As posted above, you may need a shop to do some remedial cleaning of the oil passages to get your VVT working again, esp if you’ve ever let the oil change interval go longer than recommended, or have used non-Nissan oil filters, or the wrong oil spec.

If your engine has two camshaft sprockets the timing chain has to go around, that configuration is a little more difficult to align to match the timing marks from what we hear here. It’s a good idea to have that tested again after a few days driving to make sure remains correct, esp after a timing chain replacement.