Back at the dealer with 1563 miles (6th time)

[BIGDOGx]

21 hours ago, Stephen Gaze said:

Update. Truck is home.  Done about 40 miles so far with no issues. MPG is up and truck does feel a bit smoother. 

 

GM has been in contact with me and I will be calling them this afternoon re compensation.

Hopefully you can finally enjoy your new truck now.

[kmeleon]

Glad you've got taken care of (fingers crossed). I just dropped my truck off this morning and am now in a rental. P0300 and flashing SEL this past Saturday, again Monday and again yesterday. It now has 4650 miles on the clock and it seems to be flashing the light more frequently. It all started around 1350 miles a few months ago. This is the 4th time it's been to the dealer. I've told them what I believe it to be after reading all these stories on here and the Facebook AT4 group. It has to be a broken valve spring or failing lifter at this point. We shall see. 

[SporkLover]

Anyone want to help me understand how too thick of timing teeth would cause this issued (generic misfire) without actually causing other internal valvetrain issues?

 

[kmeleon]

2 hours ago, SporkLover said:

Anyone want to help me understand how too thick of timing teeth would cause this issued (generic misfire) without actually causing other internal valvetrain issues?

 

It's probably BS but considering he got a new engine we'll never know. 

[Stephen Gaze]

Well, I am not happy. Running around today (Friday) with 1725 miles on truck. So, 100 miles with new engine. Flashing CEL. 
 

I need this truck next week to tow a camper to MD from FL. So done at this point. 
 

UPDATE: Went by dealer this morning (Saturday). Same codes. P0300. Random misfire. Same guy tried to blame the catch can. They are calling GM on Monday.  
 

Starting to think I need an independent shop to look at it. 

Edited June 12, 2021 by Stephen Gaze

[SteveG]

Update: Still got the P0300 codes. But now they want to test the injectors and EGR valve. Apparently, that was all swapped over from the old engine.

[kmeleon]

5 hours ago, SteveG said:

Update: Still got the P0300 codes. But now they want to test the injectors and EGR valve. Apparently, that was all swapped over from the old engine.

Wow man, sorry to hear about this. New engine, same ol ******. Unreal

[darkhorse220]

Whats the latest update on this Steve?

Hate hearing about issues with brand new trucks. 

[kmeleon]

On 6/15/2021 at 2:54 PM, SteveG said:

Update: Still got the P0300 codes. But now they want to test the injectors and EGR valve. Apparently, that was all swapped over from the old engine.

It's interesting you say that they swapped over the injectors, etc. Just got mine back from the dealer after a week and a half and of course they couldn't get the truck to throw the light. I get it back at lunch and sure enough right after leaving work it throws the code. Drove straight to the dealer, they can't see anything other than the P0300 and the misfire count on cylinder 1. They believe it to be a bad injector since the truck seems to run fine, even during the code. Maybe they're on to something. It would certainly explain your issues with the new engine if they were swapped over. 

[SteveG]

Update. So, last flashing CEL was at 1755 miles.  Dealer did a crank relearn. They also mentioned that this is a known problem and GM is working a software update that should be available by the end of June. Something about misfire sensitivity. Anyway, I took the truck and hit the road. 
 

Anyway, truck now has just over 3600 miles.  About 1000 of that was towing a 30’ foot 7000# travel trailer. No issues other than the abysmal mileage while towing. 7 to 9 mpg. But truck is running strong.  JLT catch can is doing its job.  Getting maybe 1/2 oz of oil in 700 miles or so. Nothing scientific. It is just good to know that I am not burning it.