2015 L86 6.2L Silverado - Fuel Injectors suspect

CadillacLuke24 · August 17, 2022

2015 Chevrolet Silverado LTZ Z71

L86 6.2L V8. 252,062 miles.

Coming home last week the SES light tripped, and it was flashing. Engine was running rough. Pull over, I happened to have a code reader on hand. P0106 (MAP sensor) and P0302 (Cylinder 2 misfire). I was able to limp home. Ran rough between 1000 and 2000, clear 2000 and it would smooth out considerably. Stopping was a questionable decision as there was a high chance of stalling. Stopping, shutting off the truck, and attempting to restart would result in a hard or no start condition.

Once home I pulled a P0106, P0302, and P015C (Bank 2 Rich to Lean - O2 Sensor delayed response). Hard starts that get increasingly difficult the longer the truck is running.

I changed the MAP sensor with marginal improvement in performance. I suspected spark may be an issue, so I pulled the plugs. They were carbon coated, though throttle body cleaner and a wire brush made it disappear. I changed the plugs and wires. That helped more but did not resolve the underlying issue.

Hoping the issue was still relatively simple, I replaced the Ignition Coils. That helped substantially more, to where I think the truck could be drivable, though there still is an issue present.

The first time I restarted after coil replacement, idle was rough and I got the same trio of codes that I did before replacing parts. I cleared them, let the truck sit for a second, and then started again. Starting was somewhat easier (though still had to turn over for about 10 seconds before it caught) and idle was somewhat smoother though still uneven. This time I got a P0300 (random multiple misfire) as opposed to Cylinder 2. The P0106 and P015C persisted.

I know I'm kinda breaking the first rule of diagnostics by throwing parts at it, but at a quarter million miles it can't hurt.

Though I'm not particularly excited about this prospect, I think the fuel injectors are suspect. I am aware of others' issues with injectors and have seen threads on this forum and videos chronicling the replacement of said injectors.

Should I replace my injectors?

Thank you for your time.

Spurshot · August 17, 2022

5 hours ago, CadillacLuke24 said:

2015 Chevrolet Silverado LTZ Z71

L86 6.2L V8. 252,062 miles.

Coming home last week the SES light tripped, and it was flashing. Engine was running rough. Pull over, I happened to have a code reader on hand. P0106 (MAP sensor) and P0302 (Cylinder 2 misfire). I was able to limp home. Ran rough between 1000 and 2000, clear 2000 and it would smooth out considerably. Stopping was a questionable decision as there was a high chance of stalling. Stopping, shutting off the truck, and attempting to restart would result in a hard or no start condition.

Once home I pulled a P0106, P0302, and P015C (Bank 2 Rich to Lean - O2 Sensor delayed response). Hard starts that get increasingly difficult the longer the truck is running.

I changed the MAP sensor with marginal improvement in performance. I suspected spark may be an issue, so I pulled the plugs. They were carbon coated, though throttle body cleaner and a wire brush made it disappear. I changed the plugs and wires. That helped more but did not resolve the underlying issue.

Hoping the issue was still relatively simple, I replaced the Ignition Coils. That helped substantially more, to where I think the truck could be drivable, though there still is an issue present.

The first time I restarted after coil replacement, idle was rough and I got the same trio of codes that I did before replacing parts. I cleared them, let the truck sit for a second, and then started again. Starting was somewhat easier (though still had to turn over for about 10 seconds before it caught) and idle was somewhat smoother though still uneven. This time I got a P0300 (random multiple misfire) as opposed to Cylinder 2. The P0106 and P015C persisted.

I know I'm kinda breaking the first rule of diagnostics by throwing parts at it, but at a quarter million miles it can't hurt.

Though I'm not particularly excited about this prospect, I think the fuel injectors are suspect. I am aware of others' issues with injectors and have seen threads on this forum and videos chronicling the replacement of said injectors.

Should I replace my injectors?

Thank you for your time.

Your thought about the injectors being suspect, prompted a memory of the late Russ Collins (RC Engineering motorcycle racing/performance products). In his later years, he started a fuel injection business. One of the services they provide is injector cleaning and flow testing. A few years back, a friend with a small foreign car wanted to have his injectors flow tested and cleaned. That was my only contact with RC Injectors. They're in Torrance, CA.

Here's their website. RC Fuel Injection > Contact

Grumpy Bear · August 17, 2022

There are three videos in this series and this guy talks and talks (he verbalizes every thought in his head :crackup: ) but might be useful. You will find links to the other two as you go.

CadillacLuke24 · August 18, 2022

See watching the first bit you tagged is exactly what Clyde is showing. Hard starts, seems like he's flooded out, last night there was a nice fog coming from the exhaust when he first fired off, and the garage had a distinct odor of unburned fuel.

I think Cylinder 2 injector is stuck open.

Changed the oil once already during this, should do that again once I replace the injectors.

Got tools to remove the fuel rails coming, will get the intake off and see if I can read part numbers on injectors.

Can they rebuild injectors cost effectively? If so it would be worthwhile to rebuild the set and keep them for spares.

Spurshot · August 18, 2022

Can't comment on "rebuild the injectors". But, they should be able to tell you which are bad and which are good. Seems like it may be cost effective to find out. But, if that's not a factor, $500 for a set, online, is a shotgun approach, if down time is a factor.

Grumpy Bear · August 19, 2022

That many miles and the location if it were me, and it isn't, I replace them all and the HPFP. Plus high side fuel rail pipe from HPFP to fuel rail. Need a 'crows foot' and torque wrench for that job.

CadillacLuke24 · August 19, 2022

Plan is all 8 injectors, intermediate pipe #1 and 2, and manifold and TB gaskets. Got crows foot wrenches, torque wrenches, and flare nut wrenches for days! Hopefully I can find intermediate pipe #1 soon....everywhere shows discontinued.

CadillacLuke24 · August 24, 2022

For what it's worth, the GM Helm Factory Service Manual recommends whenever injectors are removed they should be rebuilt. Glad I'm going the route I did.

Managed to source both intermediate pipes despite catastrophic supply. Gaskets are here and ready to go, and once I pull the fuel rails injectors will be sourced.

SO glad I kept my brother's 97 Camaro. Just a V6, but it has T Tops, leather, and the alloys that were stock back then. Just over 101k, but it runs like a top and it's in great shape. It's my work car, but he's earned his keep this month.

midwestdenaliguy · August 24, 2022

You might already know or have all of this, but I did a write-up on replacing the 6.2L fuel injectors and lines. Included torq specs as well. Wasn't a bad job. Good luck.

Grumpy Bear · September 7, 2022

Udpate?

CadillacLuke24 · May 18, 2023

I do have an update

It was not the plugs. Nor the ignition wires. Nor the Ignition coils. Nor the injectors.

After the Injectors didn't cure the issue I used my boroscope to inspect all 8 cylinders. Likely an omen, cylinder 2 showed an orange liquid in droplet form on the top of the cylinder wall. Rotating the engine didn't show any apparent damage to the piston, but the cylinder did not hold compression upon further testing.

After limping to the dealership further inspection revealed the valves let go in cylinder 2. I would venture a guess that the intake valve went first. Will provide pictures. Beat the heck out of the piston, cracking it, carved up the head something fierce, and scored the cylinder wall.

GM listed a remanufactured engine as the option but they were on an indefinitely unavailable timetable. By the grace of God I found a marine engine shop in Michigan with, of all things, a brand new 0 miles crate GM L86 6.2L V8. Got that shipped to me, the dealer installed it, and all was well.

16,000 miles later Clyde is still going strong. They did a great job on the install. They recently swapped my wheels and did an amazing job. The guy who works on my Silverado there is the Corvette dude so it seems my reputation preceded me hahaha. Out of morbid curiosity I asked if they thought repair was a viable option ( I already knew I was going to say yes) and they also said, based on the condition of the entire truck, definitely.