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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.
By John Norman
At 46,032 miles the check engine light came on. Took to my usual service center. They did a fuel injector flush service and this remedied the problem for a few days.
Light comes back on, same error. I ran a tank of premium fuel through the engine - light goes off.
At 47,300 miles the check engine light is back on. Checked the code = P050D X2.
Took to the local GMC dealer - "Performed fuel injector balance test. All bank 1 injectors low".
Repair estimate attached.
Is this common for 4 injectors to go bad simultaneously on one bank? Or can there be another problem?
The truck has a 5.3 engine.
Per the service manager this is not covered under any warranties.
The truck runs fine- quick start and no discernable hesitations or unusual engine noises.
Any direction on a remedy would be greatly appreciated.
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?
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.
I have an 02 Silverado 1500 4WD with a code P0443 (and a P0171, but I don't know that those are connected). However for now I am working on the P0443 code, Purge Valve Solenoid Circuit?
What I have done thus far: 1) Bought a new Purge Valve Solenoid, check engine light w/ code still on after clearing codes. 2) I tested the old and new solenoid with a power probe and blowing through to make sure it is engaging. ie. air can flow through with now power, but after power probe initiates the valve shuts and can no longer allow air to go through purge valve solenoid. 3) Attempted to test if power was going through to the plug going to the purge valve solenoid, appeared to be getting 12.3v. I'll admit I'm not electrical savvy, but I seemed to get voltage to the plug when the key was turned to "on" position.
Thanks, what else can I look at, or re look over?
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