Hello all:

I bought a 2011 GC with some kind of engine problem. I'm trying to identify it but so far I got confused. The mechanic suggested to the previous owner to replace the engine. It had 1, 3, and 5 misfire codes along with P0300, P0172, P0175, and P000B.
I opened the upper intake and noticed the intake manifold was cleaner around the #3 and #5 injectors, a sign of a leaky injector. I replaced them. The oil is gas smelly but oil level is not too high.
Now, the car runs somewhat funnily for a minute when cold. Then, it starts to idle high and low periodically until it dies. It keeps running if you push the gas pedal. If you wait half a day, it behaves similarly.
Both banks run still rich (P0172 and P0175), and all 4 O2 sensors confirm this (they are all ~0.9V). Fuel trims are all -30. I hear some funny sounds like grinding. I feel like the tops do not get enough oil. Next weekend, I will crank with the top off to confirm I get oil there and do a compression test. I get P0300 multi cyclinder misfire but not specific to 1 3 and 5 now.
I guess the fuel pressure is crazy high and forces the injectors to leak, or maybe there is something I cannot think of.
Do you have any inputs or such experiences? I appreciate any help you can provide. I have another 2011 van, if I need to test some components I can borrow it from the other one.

I will do compression test over the weekend.

TIA

 

I did a comression on my cyclinders. All are around 140-150psi range except #5 which is 0psi. I will remove the head and see what's going on.
has any of you removed the engine while the engine is in?

 

Were you able to identify what was causing this problem? I have the same issue on my 2013 D GC SXT. 3.6L. I replaced Air Temp Sensor, MAP Sensor, lifters and rocker arms, injectors, spark plugs, one O2 sensor, and it did not help.

 

I found the compression was zero on #5. It was diagnosed as a burnt valve before I bought it. I tried to removed the head while the engine was in the car, but could not succeded. Finally, I sold the car.