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This is my first post and I am looking for help from the experts. I have a 2013 5.3 5300 LMG LS with a cylinder misfire code P0302 (this is my personal vehicle). So far I have:
put new plugs and wires
swapped coils with number 1
swapped injectors with number 4
swapped coils with number 4
swapped injectors with number 6
Compression test :Cyl 1-165psi, 2-160, 3-170, 4-170, 5-170, 6-170, 7-175, and 8-175
All wires between injectors and coils to PCM were tested for resistance and continuity with no deviations.
Sprayed around heads and intake to test for leaks. None found
Checked all vacuum lines and connections.
Cleaned the MAF sensor.
Cleaned the throttle body.
Tested spark at the plug.
Pulled passenger valve cover and checked rockers for play and travel.
I dont have the tools to test the PCM, and only have a basic code reader for testing purposes. I am reading a higher fuel air ratio in the exhaust on bank 2 (understandably).
My question is this. I am at the point of replacing the PCM and before I do that, I am trying to figure out what I missed. In my limited years of a "professional" mechanic (I no longer am or have access to the tools), I have never had to replace a PCM, and this seems off to me. I have owned the vehicle since new and perform regular maintenance. The vehicle has NEVER overheated, and never ran low on oil or coolant. In a normal oil change cycle, it may burn off about 1/2 quart of oil. Total miles on the engine are about 110,000.
I have not disengaged the Eco mode though I think I am going to.
What have I missed on diagnostics, and what should I do before replacing a PCM?
Is there a recommendation on where to get a PCM other than Chevy?
Will I be able to install the PCM or will it have to be calibrated to the vehicle?
If there are any previous threads on this problem, feel free to post links....
I think my problem is the DOD (displacement on demand) lifters, I believe one failed. Researching the available delete kits now. Plan is to look at it Saturday, I will post after and share the results....
If anyone has any recommendations, or do's and don'ts, feel free to add them!
If all the valves are opening and closing it's not a collapsed lifter.
Does it actually have a noticeable misfire, or is it just setting that code?
If it feels like a real misfire, have you checked for signal at that injector? Checked spark for that cylinder? Is it misfiring all the time at any load/engine speed or only sometimes?
It is a noticeable misfire, mostly at low rpms, idle to maybe 2000. I definitely have spark at the plug, and have swapped coil packs to see if the spark was low or not. I definitely have fuel and the injector is pulsing. I can feel it. I am also reading excessive fuel in bank 2, which leads me to believe the injector is working. And as I said before, I have swapped injectors with cylinder 2 twice just in case. The code always comes back as #2. I have not checked the valves, just the rockers. I have gone through everything on every list I have seen for this code. The only physical parts I have not seen personally are the lifters and cam lobes. There is a slight rattle coming from the @2 area of the block, but could also be the belt tensioner. It is too quiet to really tell if it is a cam / lifter knock. The sound also only happens and is noticeable when the engine is running and low rpms. I believe my DOD Lifter is in the process of failing, and when I turn the motor by hand, it still holds up, whereas when the engine is running the spring is too weak to keep up....
I currently have almost all the parts in my cart at summit. I am still looking at camshafts and whether or not I want to upgrade a little (probably will!). I live in Fort Worth, and my shop is about 10 minutes from the new Arlington Summit. My plan is to put everything in the cart, take the intake and head off, and check the lifters. If the parts are deemed bad, I will purchase the parts and go pick them up. This way if Im wrong, I just clear my cart, and buy the gaskets to put my engine back together. This will also allow me to check my head gaskets, intake gaskets, and mounting surfaces.
This is the internals of a DOD lifter. Not mine, I collected it somewhere from the interwebs.
The locking tabs are at the bottom right. They retract to allow the lifter to deactivate, and spring back out to go back to normal-lifter mode. I am not aware of any type of failure that would make the tabs lock with the engine off and then unlock and collapse only when the engine is running.
I am definitely open to other suggestions!!! This is my first LS kerfluffel, and I am learning. At this point, if I cant find any good suggestions, I am still pulling the head. Not that hard and for $150 in gaskets if I'm wrong, Id rather be certain...
If this small spring were to weaken, or be cut in half, could it still lock when not under heavy load (like turning the motor by hand) and again lock when oil pressure is high (like high rpm)?
I changed my oil the day all this started, and I found a piece of bent wire in the pan. I work in a machine shop / truck shop, and at the time I didn't think much about it. I just assumed a piece of metal fragment fell in the pan and I didn't see it before changing the oil. In my opinion, this could very well be this spring or part of it anyway. It was only about 5 coils long but stretched out. I dismissed it because in all the other engines I worked on, there were no springs this small internally. Also, again this is my first time messing with the LS VVT and I did not know what was involved. Your picture only makes me think more about this being the case....
Clearance between the inner & outer lifter bodies is something around .00015", no way for that spring to make it from inside the lifter to the oil pan.
Do you have a scan tool capable of actuating the VLOM solenoids? I suppose a solenoid could be leaking/bypassing and (de)activating that lifter any time there's oil pressure.
I do not have a scan tool with those capabilities; recommendations for one?
I completely understand what you are saying about the lifter clearance, but after seeing your picture, it will drive me crazy if I don’t look. I think I may go through with the lifter swap either way. I just need to find a tuner that I can delete the afm, and re tune the engine for a new cam. Any good suggestions there?
Anyone interested in the update, I had the number 2 exhaust lifter chunk a little, and the cam lobe had about a .03 groove worn in the peak... I found it puzzling that the cam was only worn on the peak while the lobe base looked fine. Found a little metal in the filter, and a touch in the oil pan. All of the DOD pieces seem to be intact, but I went ahead with the delete kit. Gonna keep the VVT, did a small upgrade on the cam, and some new valve springs to help out...
About $2000 later, I'm half way finished putting it back together...
Cyl 2 misfires are noticeable at idle and low RPM no matter the engine temp. I have already swapped cams, done the DOD delete, and am in the process of reinstalling the heads and intake. There was definitely some damage to the cam and lifter for Cyl 2...
Question for a friend: how many bolts are okay to leave inside the oil pan?
It was the cam and lifter for cyl #2, and nothing to do with DOD I have completed the cam swap and deleted the DOD anyway. With the help of PC tuners, I have done the MAF tuning. I am in the process of VVE tuning and the like. Thanks for the help to those that tried!!
02-03-2021, 06:10 PM
2013 5.3 p0302 
