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Discussion Starter · #1 ·
I’ll start off by saying this is my sister in law’s car. It’s got 95k miles, she bought it at the end of 2020 with 20k miles on it. She’s not the best with keeping maintenance often waiting till 7-10k miles between oil changes. Today she called me and thru me on the phone with the dealer service advisor (not tech) with no real info other than ESC on the dash and engine light blinking and car feeling like it wasn’t maintaining power, I told her to take to dealership and let them know. Service advisor said it was a P0171 and they would update later. This started initially around 10am or so. S.A. called her back at 1700 and said tech stated there was misfire on cylinder 1 & 2 (which I already knew from blinking engine light, just not which cylinder’s). He goes on to say that the tech advised she needed a new engine evidence by blow by he saw which pointed to a failed piston ring. I get to the dealer 15 minutes before they close (1800), she pays the diagnostic fee and we go outside to check the car out. Upon opening the hood I immediately see oil specks all over the passenger side of the engine cover, they aren’t smearable though. I have her start the car and I can hear the misfire. I then open the oil cap and can see white smoke coming out (not thick but noticeable when I had my flashlight on it since it was dark), close the cap and pull the dipstick up and same thing. Check the exhaust and sure enough, more white smoke.

Searching the google P0171 reveals a whole range of issues, mainly with the air intake system but also fuel injectors. I could hear a whistle, when the car was running, somewhere on the left side of the engine but unable to pin point anything in the dark.While I have done a good amount of work on my previous vehicles, cylinder work is not something I’ve done. Could there be a relation between piston ring and P0171?
 

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2016 Malibu 1LT 1.5T/6-speed 6T40
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Did you confirm that the only code was P0171? The lean code is not usually the only code with piston ring failure. Usually you have P0300/P030x along with the flashing check engine.

The blowby, misfires, and white smoke isn't good and isn't usually partnered with a lean condition. Those along with the history would point toward pistons. Did the dealer verify the bad cylinder with a compression test?
 

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Did you confirm that the only code was P0171? The lean code is not usually the only code with piston ring failure. Usually you have P0300/P030x along with the flashing check engine.

The blowby and white smoke isn't good and isn't usually partnered with a lean condition. Did the dealer verify the bad cylinder with a compression test?
I only have the service write up. Says they vacuum tested crank case and was above 5psi. The printout with the CEL code only shows P0171, no other codes.

Edit: The CEL does flash as well.
 

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2016 Malibu 1LT 1.5T/6-speed 6T40
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Positive crank pressure could mean PCV orifice clog. It could also be from the blowby. That would also give that whistle you noted. If you pull the dipstick does the whistle stop? Very strange they would diagnose catastrophic engine failure without verifying compression loss in a cylinder.
 

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Positive crank pressure could mean PCV orifice clog. It could also be from the blowby. That would also give that whistle you noted. If you pull the dipstick does the whistle stop? Very strange they would diagnose catastrophic engine failure without verifying compression loss in a cylinder.
The dip stick was pushed in when I heard the whistle. That being said the whistle would come and go, every few seconds or so, and last equally as long.
 
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