Armycat10

I have a 2010 2.4l 190K Miles drive and run great down the road. But when at idle is rough more after it warms up. Using the OBD Torque app on my phone with a Bluetooth ODB2 reader. I can see tons of Misfires on cylinders 2 and 3. Also, get a P0300 Code.
I have replaced the following
Intake & Exhaust Camshaft Position Actuator Solenoid
Ignition Coils
Spark Plugs
O2 sensors (both)
exhaust manifold (Had a Crack)
catalytic converter
New Intake seals
New throttle body seal
New Valve cover gasket

Cleaned MAP sensor
New Air Filter

Checked compression on all cylinders and have good compression
Check Fuel Pressure and that is good also.

Going my scans it mainly misfires at idle.
Could this be a timing chain issue? I checked Chain when I had the Valve cover off and did not seem loose at all but I have heard this being an issue.

ruley73

The only thing cylinder-specific thing left that you haven't tried is replacing fuel injectors. Try switching the middle two around with the outside two. See if the misfires follow and go from there. The intake valves may need to be cleaned too since it's a direct-injection engine.

To answer your question, I suppose it could be a timing chain issue, but it doesn't seem likely.

kevinkpk

How about plug wires?

ruley73

It doesn't use plug wires. The coils sit directly on top of the spark plugs.

Armycat10

So swapped fuel injectors #2 to #1 and #3 to #4. Also clean up the valves as best as I could without removing. They don't look to bad but always could be cleaner and not much change except now it's misfiring more on #1. Only #4 is only misfiring every once in a while. Still only misfire during idle. Drove about 15 miles and did not misfire once.


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Armycat10

So update,
Put in new Injectors and High Pressure fuel pump (No Change)
Also replace MAF sensor (No Change)

Have found that it only starts misfire after it has been running or warmed up for a while.
If car is cold it runs without issues.
So I did another compression test.
When car is cold getting around 110-120 PSI on #1 and #4 and 90-100 PSI on #2 and #3
After warmed up and starting to misfire now getting 60-90 PSI on #1 and #4 and 60-70 PSI on #2 and #3.

Could this be a blown head gasket? Why would it only affect it at idle? Doesn't misfire while driving down the rode only at idle.
Doesn't use any noticeable oil or Water. No White or black smoke. No blow by coming when take of oil cap while running.
Do notice moisture on the inside of oil cap not sure if that is normal?
I have a Head Gasket but I would have to remove Timing Chain so I will need gasket for timing cover also.
Thanks,

Armycat10

So another update. Got on to Justanswer.com so I could chat back and forth with a Chevy Mechanic. This is a great site for all you DIY Mechanics as they will help point you in the correct direction. Normally get a response within 5-15 min after each post.
He thinks it's more of a timing issue. So took the Valve cover back off and I noticed there is a lot of slack in the chain between the two cams.
Ordered a new Timing chain, Head bots, Cam Bots and will be putting in a new head gasket and timing chain Wednesday.
I will update once it is done.

Armycat10

Update:
So got both the new Timing Chain and Head gasket in. Let it run for about 20-30 min and going by my reader only had 2 misfires in Cylinder 3. I am going to get a compression tester today and see what we are getting now.

Armycat10

So Timing chain/Head Gasket looks to have corrected my issues. Now getting 110-120 PSI Which is not great but better and no longer getting misfires.
Thanks