Rough idle and no power (2013 LT Manual)

[2010ngojo]

Hi all,

I recent got a 2013 LT Manual with a lot of miles on it. The car ran fine, and I was able to drive it home on a 50-60 mile trip with no major issues. After sitting for a few days, recently my nephew went to get some gas for it, and after 7-10 minutes the car went into limp mode and the check engine and traction control lights appeared. Rough idle and several misfires, mostly on cylinder 2. Seems to run fine when revving the engine, albeit lacking its usual power. The expected 84 code also appeared.

Here are the DTC codes I see:
P0300 - general engine misfire
P0302 - misfire on cylinder 2
P1101 - intake air flow issue
P0068 - manifold pressure /throttle body issues
P0106 - maf sensor issues
P0171 - fuel trim system lean

I have been researching the various common issues with the car and the 1.4t engine prior to getting the car. I know 1.4t engines are prone to pcv and intake manifold issues, so these codes are likely related.

Can anyone give some live data on how the engine should run when idling? Also, my fuel system 1 isn't being shown for some reason. I'm interested in these readings: Throttle position sensor (TPS), Mac sensor reading, map sensor reading, fuel pressure, or any other value any of you think I need to check. Or if you want my freeze data, I can give that too. It seems to be related to the air intake system judging from all the codes.

Due to the sheer cold weather, I cannot troubleshoot further into this at the moment.

Thanks.

Edit: one think I forgot to mention. I did check the valve cover vacuum diaphragm. The small port is not sucking any air (or blowing any air for that matter). Tried to check the check valve in the intake manifold but it's too dirty and dark outside.

From what I understand, the missing or worn check valve inside the manifold would cause the diaphragm to rupture and cause the rough idle. However, it seems the diaphragm is not ruptured, so why the rough idle?

 

[FesterJester]

Did you check you air intake and filter?
I had one plug up on my Saturn once.
Dang mice dragged a bunch of stuff into the air box and plugged it enough to cause airflow problems.
Restricted airflow from the start will cause many of the codes related to MAP, MAF, and lean.
Next I would check the vacuum and boost lines. One of mine cracked and caused turbo problems on my '14 sonic.

As for the misfire, maybe a coil pack or spark plug has failed?
Pull the #2 spark plug and look to see if it is clean or wet and dirty.
If dirty, I would try a new spark plug first, then a coil pack.
I know you can test the coil packs with an ohm meter. Not sure what the values are supposed to be though.
If clean, maybe the fuel injector is clogged or failing. Maybe the wires to it?

A funny thing happened to my '14 sonic last year.
A squirrel or something chewed off some of my wire harness.
Completely chewed off the wires to my MAP sensor and chewed one of the ground wires on the right side of the engine harness.
It took me days to figure out the missing ground because it would make enough contact to run, but would start causing strange problems when driving down the road.
It actually put the car into limp mode most of the time.

I hope some of this helps.

FJ

 

[skurtov]

It more than likely is the diaphragm. if it hasn't failed it will fail, get it bypassed.