L86 Miss Fire
Thread Starter
Teching In
Joined: Jul 2025
Posts: 2
Likes: 0
L86 Miss Fire I have a 2017 escalade 6.2L L86 with 245,000km. It is new to me so I do not know the history of it. I have only put about 1700km on it. On cold starts it will sometimes throw a cylinder 3 misfire code. It has given me a P2101 code once. It also has had a PO50D a few times. I have put new spark plugs and wires on it. I also swapped cylinder 1 and 3 coils and the misfire did not move. I pulled the intake off and clean the intake valves. So far nothing has made a difference. I would greatly appreciate any input on what the issue could be, Thanks in advance. Attached is a HP tuners recording of a cold start.
I just had the same issue pop up on my 2016 Yukon Denali with 167k miles. My missfire was cylinder 2 though. The missfire would clear up if i brought the revs up to 800rpm. Mine was lifter failure.
Thread Starter
Teching In
Joined: Jul 2025
Posts: 2
Likes: 0
TECH Apprentice
Joined: Jan 2023
Posts: 340
Likes: 47
From: Corpus Christi, TX
These systems are very touchy when it comes to fueling. I will add that on the ones I have worked on recently that is unfortunately an injector issue as the compression numbers are always on par with eachother and even taking the heads to get "rebuilt" the shop always says the valves are good. I saw a local shop chase a misfire by replacing the whole valve train thinking they would solve it when it was infact a injector issue. These DI injectors can either be a really good batch and last forever or clog up in less than a 100k miles and exhibit these symptoms.
Unrelated me and my neighbor now own 2020 L84's? And mine stock runs perfectly. His has a huge upgraded aftermarket intake pipe and is experiencing P0300 from running lean in my opinion as I took a log and the MAF freq is so far off mine its not even funny. His whole LTFT chart is red indicating it overfueling. Make sure you are scanning these systems before making any diagnosis is all I can say
Not saying I have a good lead at all but damn I hate some of these batch made injectors that should have been made with larger cooling surfaces imo.
Unrelated me and my neighbor now own 2020 L84's? And mine stock runs perfectly. His has a huge upgraded aftermarket intake pipe and is experiencing P0300 from running lean in my opinion as I took a log and the MAF freq is so far off mine its not even funny. His whole LTFT chart is red indicating it overfueling. Make sure you are scanning these systems before making any diagnosis is all I can say
Not saying I have a good lead at all but damn I hate some of these batch made injectors that should have been made with larger cooling surfaces imo.
On The Tree
Joined: Sep 2009
Posts: 113
Likes: 59
From: Akron, OH
I chased a cyl 3 misfire in my 2018 L83 Silverado for like a year and a half. I did plugs, wires, swapped coils, injectors (common with the P050D), and then it sat for a couple months while I was doing another repair. Upon startup the cyl 3 intake lifter didnt pump back up and ate the wheel and cam lobe.
When you are having the code, I would take the valve cover off the driver side and wiggle the rockers when the valves are fully closed. If one is loose you have a lifter going down. If not it might just be injectors, but I wasnt so lucky.
When you are having the code, I would take the valve cover off the driver side and wiggle the rockers when the valves are fully closed. If one is loose you have a lifter going down. If not it might just be injectors, but I wasnt so lucky.
