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By Zack Coles
2016 Silverado 1500 5.3L 6- speed RWD. Approx 105k at failure. See "Shudder: Root Cause (1)..."https ://www.gm-trucks.com/forums/topic/249007-shudder-root-cause-1-at-higher-mileage/ for issues with tach bouncing and shuddering.
Occasionally get cold start code, in L.A. area, usu while in a hilly terrain in early morning. Tried injector cleaner and new spark (at some back-alley shop), seemed to help for 5-7k, but it came back and more frequent. Eventually had a fleet shop look at it, followed GM service guide and checked for coolant leak (none) then replaced injectors- I don't have a lot of downtime, so I wanted to get ahead of this issue. No Cold Start codes but less than 1k later, went into limp mode (Low Fuel Pressure code, I believe), and eventually had to be towed (wouldn't start that day but fired right up the next morning in the shop). Had this truck since 30k, and no notable issues.
Mechanics found that the high-pressure pump (fuel injector pump) was missing a bolt head and there was a gap at the pump mounting. Looking at the bolt, it appears to have been over-torqued (threads near shoulder were wore down), but I haven't had issues for over 70k. Either previous owner had shudder/trans issues and mis-diagnosed as misfire, or bolts are inclined for early failure (lots of rough freeway, like L.A., last 50k). Either way new gasket and bolts resolved that issue.
What’s up guys,
Having a random cold start rough idle issue with my ‘16 suburban with the ecotec 5.3. This happens completely randomly, typically when colder temperatures outside but not always. MIL will be triggered but will go away after some driving. Some instances it flashes and then will go off. Sometimes when the light is triggered the ABS and stabilitrack light will be on and the transmission will roughly upshift and downshift. The indicator light will go away and typically the shifting will be fixed by shutting the vehicle off for a period of time and then re-starting everything will be back to normal.
From what hat I have gathered U0401 means that the transmission control is not getting good signal during these times.
In regards to the engine, I have between 5-20 misfires counts on all cylinders except #7 which has 80 and #8 which has over 6,000.
Obviously there is a problem with #8, being a non AFM cylinder and being of random occurrence I’m thinking injector or coil pack. Any thoughts?
Well my 2014 GMC Sierra (purchased new) with less than 30,000 miles showed a Malfunction Indicator Lamp (MIL - Engine Symbol Light) on dash last Wed - May 8th.
I called OnStar and received the report via e-mail below - Code P050D. Truck ran fine.
Scheduled truck into the dealer for Fri morn May 10th. Dealer kept truck until around noon the next Day to make certain code did not reappear on cold start.
I picked up my truck and no problems since the P050D. Here is some of the repair receipt:
#1 - 3202: Engine Repair
Installed laptop and was unable to duplicate concern at this time. Tech tested and test drove several times and was not able to duplicate. Advised customer
to return if concern returns. No repairs were made at this time.
$85.00 plus tax. Is this it for diagnostics? Seems to me like the tech cleared the code - drove the truck - no code - calls it good.
Drove truck yesterday on a 60 mile 90 percent highway trip and mileage on dash showed 19.2.
Here are the results of your recent On-Demand Diagnostic request on your 2014 GMC Sierra.
VIU - OnStar System
No Error Code Found
TCM - Transmission System
No Error Code Found
SDM - Airbag System
No Error Code Found
ABS - Braking and Stability System
No Error Code Found
ECM - Engine System
IGNORE UNKNOWN DTC
No action needed
• Odometer: 29778 Miles
• Remaining Oil Life: 57%
If you require Roadside Assistance, please contact (866) 415-5838.
Please bring this email with you when you go for service.
Please see your dealer for service.
So for the last 6 months or so my truck has been throwing P050D cold start rough idle. I'm at 36k on the truck and it's a 2015. I brought the truck into the shop for diagnostics. They confirmed that for 1-2 minutes on a cold start condition, cylinder 4 misfires for about a minute or two then stops. They confirmed this multiple times. They verified no vacuum leaks, spark plugs and ignition coils checked out fine, bore scoped the cylinders and found no issues and no coolant leaks, they did a bunch of rebalancing and program checks, verified the related sensors, essentially everything with the exception of checking the injector itself because of the process and time it takes to do so. I know that these newer trucks send double pulses to the injectors during cold start until the truck warms up then it goes back to normal pulse frequency. I guess my question would be what is more likely? The fact that the injector is bad or that during the cold start the injector isn't receiving the pulses? I imagine that all the injectors would be wired in parallel to an extend and that all injectors would essential receive the same signal so I feel that the later is less likely and more than likely the injector itself. But the auto shop won't confirm that the injector is the actual source of the issue because they couldn't test it.
Hi guys, I need some help.
On Thanksgiving I had remote started my truck to go make the last minute run to the supermarket. As I left my house to jump in and take off, I found the truck’s engine had stopped. When I started the truck with my key, the check engine light was on. I took it over to my local dealer and after a week and a half, I was told my aggressive treads (Nitto Trail Grapplers) could be the cause. The work order stated the tech swapped out my wheels and tires for a set of factory wheels and tires and could not get it to misfire. The work order also stated that code P050D was found. I did read in several treads this has come up and injectors was normally replaced. My truck was purchased in Oct 2014 and had 25606 miles on it when I took it in. There are a ton of lifted, leveled, stock trucks out there with the same tires so was wondering if anyone else had this issue. It’s really hard to accept that my tires (which has been on since 2014) is the cause.
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