300 Blackout

One of my aftermarket plug wires was getting cooked by my headers. As the wire heated up, electrical resistance increased and I’d get a similar symptom of a misfire with no codes as long as I was driving normal. It finally threw a code when I opened it up. Under normal driving, it conducted enough energy for ignition. Once it was under load, it couldn’t produce enough spark to ignite that quantity of fuel & pressure, so it missed repeatedly and threw a code. I replaced the wire and problem was solved. Also, if you have ever brought it into the dealer for warranty work, recall, service, etc… there’s always the possibility they re-flashed your ECM to update it. If so, your AFM might be operating again and you’re perceiving that as the hiccup.

Thanks for the advice pokismoki. I have no interest in the 8 speed. I like the 6L80/90. Never thought of the 4L75 and I’m not sure what that would involve to make sure I keep 4x4. I’m not really looking for the fastest truck, just a dead nuts reliable workhorse. Really great info about the oil pump, thanks for sharing. I’m running around 550 ft-lbs torque right now with plans to go higher. Spoke with Circle D Trans and TK Performance and a 6L80 rebuild is gonna be anywhere from $2500 - $4500. Then another grand for a converter. I was thinking of just swapping my current tcm/valve assembly directly into the 6L90 to avoid any programming trouble. Update the tune for the 90 and fabricate the frame crossmember mounts. Trans output shaft would need to be custom ground for the transfer case along with a custom tail housing adapter. Last piece needed would be a slightly longer front driveshaft. I think that covers it but haven’t met anyone who completed it. Now that I wrote all that out, I’m in agreement with you that rebuilding the 6L80 seems like the better option. Similar cost with a known result. Now to find an oil pump…

I have a 2014 L83 with a 6L80 4x4. Instead of rebuilding the trans, I’m considering moving up to a 6L90 if it’s possible. Does anyone have info about this or know of anyone who has done it?

Replaced my negative battery cable four months ago and it hasn’t happened since. I even re-tapped the treads on the frame to assure it’s getting good contact. Fingers crossed.

Years ago I bent one of the MAF sensor pins when I reconnected the wiring harness to the terminal. Idle was terrible and my fans wouldn’t stop running. Might be something to check.

Without question, this is exactly what is occurring on my 2014 Sierra L83. I’ve been chasing it for about 2 years. It first presented as flickering/dimming of the interior and exterior lights when rolling up two windows simultaneously. It occurred intermittently and I originally believed it may be due to an excessive load from some aftermarket accessories (supercharger coolant pump, HIDs, wideband sensor, bigger tires). AGM Battery less than 2 years old in a cold climate so I figured it was the alternator but the problem resolved itself so I chalked it up to excessive idling in the winter with too much demand in the system. Six months later, the problem reappeared. Slow speed turns while parking caused the truck to die. It didn’t die every time. Sometimes the lights would flicker, advisory messages appeared in the driver info screen telling me StabiliTrack was disabled, and steering lost power. I never lost braking power and I speculate that is because I deleted the mechanical vacuum pump years ago and run off of manifold vacuum supplemented by a vacuum reserve canister. I purchased a 200amp alternator but didn’t install it as the problem appeared to have resolved itself before I got around to putting it in. Then the problem re-appeared many months later and was obviously correlated with weather (hot and humid, raining or long idle during winter warm up) and vehicle speed (always at low speed while parking or low speed maneuvering). Again, by rolling two windows up at once, I could induce the flickering, StabiliTrack disabled, “roll the drivers side window down then up.” Parked the truck a few days ago and experienced the power steering loss. It was in the sun for a few hours and when I went to move it, it was dead. Dead, dead. Not a single light. Nothing. I charged it, drove home without issue and that brings me to today. I drove for about 15 minutes in hot humid weather. I pulled into a parking spot and needed to check my drivers side wheel well for an unrelated issue. I turned the wheel to the right while parked and running at idle. I knew it would set off all the bells and whistles, which it did. Took care of what I needed to and started turning the wheel to the left. After about a quarter turn, the truck instantly died. Not like the previous times. No stutter, flicker or dimming. This time it was instant blackout dead. Tried to restart the truck...nada. No lights, no power. Popped the hood, looked around for anything obvious didn’t find anything (as expected). Opened and closed the drivers door. Put the key in the ignition and had full power, started right up. No struggle like you see with a dead or failing battery. Nope, it started like nothing happened and had the driver’s window message. Although frustrating, it was really useful info to have. It’s not a dying alt or battery. Definitely something different which led me here and to this post. I get the feeling SR01 might just be a tech who sounded the alarm about this issue and it fell upon deaf ears. Regardless, thank you for creating an account to share this information with us. It’s your first and only post and I’m grateful for it. Thanks!

No, it’s a V8.

All you need is the canister and the 1/2” to 3/8” adapter. The canister comes with a check valve; it’s a 90 degree fitting that connects into the large port on the canister. There’s a check valve already at the booster and the PCV valve is a check valve so you’re covered. Pick up some constant tension hose clamps (or similar) and you’re good to go.

I’m in Michigan too. The dealer should still be able to repair your vacuum pump and perform recall service. I believe that qualifies as a critical service since it’s a safety item on your vehicle and you need your vehicle to get food, supplies, etc... might be worth a call if you haven’t already. I wouldn’t use an electric vacuum pump again. It constantly ran and struggled to keep up. Mine weren’t cheap pumps either. Another consideration is that if you have any problem with your electrical system, the pump might not function. Obviously a problem with the electrical system is concerning in and of itself. I had a low voltage situation about 3 months ago. While running the truck with a lot of load on the alternator, it would shut the truck off when I executed a low speed turn (increased load due to electric steering assist). Definitely wouldn’t want to lose brakes because of it too. Before you remove your mechanical pump, make sure you have the two screws that block off the oil galleries in the block. Super simple install, thread locker is already on them. I can’t remember the GM part number for them but they’re like $5 for the pair. Also, you can still order a vacuum reservoir from Summit and have it delivered to your house. The canister they offer comes with everything you need (not the hose), including the one way check valve. I think mine was like $35.

It should but confirm it on your own before running it. I’ve had absolutely no problems and think my brakes perform better compared to stock. I used to run out of brake assist briefly when applying my brakes multiple times in a row (slow speed maneuvers requiring repeated braking). Now, that’s pretty much unheard of and way better than the mechanical or electric pumps. I think the reservoir is a big help and would probably be a good idea even for the guys running the mechanical pump. Obviously, you really need to be smart about this because it’s your braking system. Make sure you’ve got a check valve on the line between where you spliced into your catch can’s outlet line and the reservoir can. The brake booster already has a check valve where the line connects to the booster. Be sure to check that the valve is installed in the correct direction. I know it sounds obvious, but it’s an easy mistake to make (which I did) so just be smart and double check everything.

How much was it to get the fob programmed?

Really slick!

Assuming I were to purchase a custom instrument cluster/gauge faceplate, is it possible to change what data channels are displayed on each of the analog gauges? For example, could I reprogram the four small gauges above the speedo and tach to display wide band AFR, vacuum-boost via MAP sensor, trans temp, etc...? (I know I’m mixing channels that are normally monitored by the ECM with aftermarket channels... just wondering if any of it’s possible) Also, assuming my tachometer gauge faceplate had the appropriate numbering and hash marks, could the needle be reprogrammed to display values above 6,000 rpm? I’m specifically interested in the analog gauges on non-Denali clusters. Thanks for any help and info you guys can provide.

Looks sweet! Probably rides great too.

I had about 70k miles on my original pads and rotors. Rusted to crap from Canadian and Michigan winters. They creaked and squealed at about 68k and I decided to replace them with raybestos police rotors and their Element 3 pads. It’s very important to properly break-in the new rotors and pads. Raybestos outlines the procedure online. I overheated them when I broke them in and glazed the rotors. Soon after, they squeaked too. I was able to scrape the rotors enough with a scotch-brite pad to remove the glaze and haven’t had any noise since. I also cleaned and lubed my parking brake components to address the issues described in the post above yours and it solved my creaking problem. Brakes are quiet now and have been for a year. Also, even my raybestos rotors are beginning to rust. I was really impressed with the OEM rotors after 68k miles in the rust belt. Yeah, they were rusted, but the contact surface was even and had a lot of life left if I wanted to salvage them. The OEM pads were dead.