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2012 Sentra Misfiring


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Hi, I'm not very car savy so please go easy on me. Lol I have a 2012 Nissan Sentra with almost 187K miles on it. Until about 170K miles or so it started through a misfire. This was in June of 22' I believe.The first code was P0301. My father and I replaced the head gasket, didn't work. We replaced the spark plug for cylinder one, didn't work. We swapped the coil packs to see if it'll show a differeny code, didnt work. Then I bought all new spark plugs and coil packs, same brand, guess what?...It didn't work. So I took it to a shop and was told it lost compression in cylinder one and it'd be around 8-10K to put in a rebuilt engine. Well as a nursing student 8-10K wasn't in my checking account. Not to mention it's burning oil so I decided to just make sure to check the oil when needed and go from there. 

Well, this week, I noticed there was a lag when attempting to accelerate but if I left off the break slowly, it's okay which I found very odd, obviously.  Lol So I figured it's probably throwing additional codes, or DTCs. 

P0302: Cylinder 2 Misfire 

P0300: Multiple Misfire Detected

P0725: Engine speed circuit input -This is called a VSS and is 60.00 at autozone. 

P1725: Electronic throttle control 

P0744: A/T Torque converter Cluth solenoid valve function 

I'm aware it's a number of things but I'm wondering what would be the most cost effective fix to start with? I haven't started working full time so getting a "newer" used vehicles isn't in the cards for me at this time. Any advice is appreciated. 

2 Answers

Why did you replace the head gasket? Was there evidence of leakage?

What were the compression readings? If you have one or more cylinders with a compression problem there is no solution other than replacing the engine or replacing the car. If you had a burnt valve causing the loss that should have been noticed when the cylinder head was off, which likely means worn/broken rings or scored cylinders,. (That price sounds way too high for a rebuilt engine though.)

The transmission code is worrisome, you could replace the engine only to have the transmission crater on you in short order. Note that model is notorious for transmission problems:

I would not put any big money into that thing.

We replaced the gasket because we saw oil on the bottom of the spark plugs.

I did have a compression test done. Cylinder one had lost compression. If I'm remembering correctly, cylinder one was reading at 130psi while the others were at 180psi. And yes, 8-10k for a refurbished engine is what they told me. I'm having another diagnostic done just to see what patch work can be. It's basically putting a small bandaid on a gaping wound but I need it for another 6-8 months so I can save and get a new used car that won't be a Sentra. Lol

Posted by: @alexrh96

We replaced the gasket because we saw oil on the bottom of the spark plugs.

OK, though that's usually caused by worn rings, valve guides, or valve stem seals - not the head gasket. In any event, a leakdown test should pinpoint the source of lost compression.