Jump to content

Engine misfire

Metro12
 Share

Recommended Posts

Metro12 Enthusiast

Metro12

Posted
Posted

I have a 2019 NBS 5.3 with 20,700 miles.  Yesterday I took it out after it’s sat on a trickle charger inside a garage since October.  I got a shudder at slight acceleration and a check engine light flashed.  Turned it off, noticed reduced power and the shudder/engine light came on again.  Checked under the hood and found a mouse nest under the engine cover.  Towed to dealer.  Dealer called that evening and said it had a code for a single cylinder misfire, they moved the spark plug and then got a misfire on that cylinder, so said the plug need replaced.  They said no wires were chewed, so the mouse didn’t cause it.  Also said the oil cooler line had a leak that would be a warranty repair.  I agreed to replace the plug since I was already on the hook for shop time since it’s not under the power train warranty.  Dealer calls this afternoon and said another cylinder is misfiring and they moved that plug and the misfire followed and now they’re pushing for a $699 “tune up” to replace plugs and wires.  I told them no.  Plugs, wires, brakes, rotors, oil and filters are within my capabilities and work I’ve done in the past, it’s $100 for me to cuss and scream for an hour in my garage and do it myself.  What I’ve never done in the past is replace plugs at 20k miles, nor have I had a plug fail and 12hrs later have another one fail.  I told the dealer I’m concerned something else is wrong and they’re just replacing plugs.

 

Any ideas on something else that might legit be wrong, or are they just trying for a $699 spark plug job?

asilverblazer Senior Enthusiast

asilverblazer

Posted
Posted
17 hours ago, Metro12 said:

Dealer called that evening and said it had a code for a single cylinder misfire, they moved the spark plug and then got a misfire on that cylinder, so said the plug need replaced... Dealer calls this afternoon and said another cylinder is misfiring and they moved that plug and the misfire followed...  What I’ve never done in the past is replace plugs at 20k miles, nor have I had a plug fail and 12hrs later have another one fail.  I told the dealer I’m concerned something else is wrong and they’re just replacing plugs.

I don't disagree with their diagnosis but I agree with your concerns too. 

 

All you can do is check the codes and inspect the plugs yourself to confirm. 

  • Thanks 1
Metro12 Enthusiast

Metro12

Posted
  • Author
Posted

Called GM CC, and expressed my concern that two plugs went bad at 20,700 miles, 70,000 miles ahead of the service schedule.  
 

wait and see

Metro12 Enthusiast

Metro12

Posted
  • Author
Posted

Sat since late October but I started probably every other week, pulled it out and ran it for 15-20min 

newdude Senior Enthusiast

newdude

Posted
Posted (edited)
1 hour ago, Metro12 said:

Sat since late October but I started probably every other week, pulled it out and ran it for 15-20min 

 

 

That's likely the problem and why you've got one or more plug bad.  If it sits for long periods of time, don't start it until you are planning to drive it.  Floods the cylinders on these DI engines and fouled the plugs.  The Corvettes are notorious for this.  We've had 3 different C8s in for it.  Owners started them in storage.  Come off the tow truck running on 3 or 4 cylinders.

 

If you are thinking of engine lubrication purposes, if you really must, put your foot to the floor with the gas pedal to enter clear flood mode.  This will crank the engine without firing the fuel injectors.  

 

 

 

 

Edited by newdude
asilverblazer Senior Enthusiast

asilverblazer

Posted
Posted
34 minutes ago, newdude said:

Floods the cylinders on these DI engines and fouled the plugs.

 

If you are thinking of engine lubrication purposes, if you really must, put your foot to the floor with the gas pedal to enter clear flood mode.  This will crank the engine without firing the fuel injectors.

I wonder why this is happening?

 

Why the need to enter "clear flood mode"? Once the engine has fired and ran any amount of time the extra fuel from a flooded engine should have been cleared.

 

I would think if it is so rich to cause these significant of miss fires it would kill the catalytic converter too.

newdude Senior Enthusiast

newdude

Posted
Posted
1 hour ago, asilverblazer said:

I wonder why this is happening?

 

Why the need to enter "clear flood mode"? Once the engine has fired and ran any amount of time the extra fuel from a flooded engine should have been cleared.

 

I would think if it is so rich to cause these significant of miss fires it would kill the catalytic converter too.

 

 

In storage sense, clear flood would allow the engine to crank and circulate oil without actually firing the engine.  

  • Thanks 1
Metro12 Enthusiast

Metro12

Posted
  • Author
Posted

So, if not driving it once every week, either let it sit on the trickle charge and don’t start, or start and rev the engine WOT? 

Bikerjon Enthusiast

Bikerjon

Posted
Posted
1 hour ago, Metro12 said:

So, if not driving it once every week, either let it sit on the trickle charge and don’t start, or start and rev the engine WOT? 

No. newdude is advising leave it sit on trickle or do not start it but crank the engine over at WOT or gas pedal pinned to the floor. Gas pedal pressed all the way down turns off the fuel injection, (engine will not start). This will allow the oil to circulate without starting and flooding the cylinders.

  • Thanks 1
Metro12 Enthusiast

Metro12

Posted
  • Author
Posted
9 minutes ago, Bikerjon said:

No. newdude is advising leave it sit on trickle or do not start it but crank the engine over at WOT or gas pedal pinned to the floor. Gas pedal pressed all the way down turns off the fuel injection, (engine will not start). This will allow the oil to circulate without starting and flooding the cylinders.

Ahhh, ok.  I was unaware such a feature existed!

Truck ran fine for the ride home from the stealership.  They replaced the second spark plug for no charge 🙄

 

Anything available to try and clean out the gunk that’s built up?

asilverblazer Senior Enthusiast

asilverblazer

Posted
Posted

I think the best solution is to drive it once a week. Long enough to get up to operating temperature and burn off any condensation that builds up (prevent sludging the oil). This would prevent any build of "gunk" too.

  • Thanks 1
Gangly Senior Enthusiast

Gangly

Posted
Posted

Fuel stabilizer might help as well.  I put Stabil in darn near anything that is gonna sit dormant for a month or more.

ember1205 Senior Enthusiast

ember1205

Posted
Posted
30 minutes ago, Gangly said:

Fuel stabilizer might help as well.  I put Stabil in darn near anything that is gonna sit dormant for a month or more.

 

Stabilizer may help to prevent the issue from getting worse, but I don't believe it will help to clear any buildup that's already there. A fuel system cleaner would be more adept at that. One could even add a heavy dose of SeaFoam to the gas. I've use SeaFoam in small engines to clear buildup in the carbs by putting a few oz in a half tank of gas, running it for five minutes, then shutting it down to sit overnight. After that, I run the rest of the tank dry and continue to add 1oz per tank going forward for a few more tanks of fuel. Seems to help substantially.

  • Like 1

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
 Share
Go to topic listing

  • Recently Browsing   0 members

    • No registered users viewing this page.

  • Forum Statistics

    250.4k
    Total Topics
    2.7m
    Total Posts

  • Member Statistics

    342,739
    Total Members
    8,960
    Most Online
    JimmyB4
    Newest Member
    JimmyB4
    Joined

  • Who's Online   0 Members, 0 Anonymous, 643 Guests (See full list)

    • There are no registered users currently online

  • Latest Articles

  • Posts

    • Another JR
      Trim level custom/pro

      By Another JR · Posted

      Are you going to take long trips in it?  If so, try out the seats in the various trims. For me the lower trim level seats were not comfortable. 
    • mikeyk101
      2014 - 2018 Chevrolet Silverado/GMC Sierra

      By mikeyk101 · Posted

      I have a 2016 that I bought new and still own. I'm around 129,000 miles now. The biggest problem was a transmission failure about 2 years ago around 95000 miles. No warning, just failed while driving down a back road. A reman GM transmission installed and it's been fine ever since. A few other minor problems along the way. I am in no hurry to replace it. It's been paid off long ago and do plan on driving this as long as I can.   I will admit I am leery about all the additional electronics in the newer models and feel that it is just more potential problems. I think there's actually more than I would have wanted in this 2016 but so far so good. I think even if something major like lifter failure happened, it would still be cheaper to at worst, drop a new engine in than buy a new vehicle. 
    • KARNUT
      OCI, not when but why?

      By KARNUT · Posted

      I’ve own several successful businesses. I’ve bought homes and lived in different states. I’d witness several generations buy homes and survive in different economic circumstances. You get awful sippy when people have different experiences than you do. You live a life. I’ve lived a life. It seems our experience has been different. You can point out generalized statistics. Some people learn how to thrive when the odds are against them. Living in different states does make a difference in a persons quality of life and economic outcomes and opportunities. That’s a fact Jack. It’s my truth, my life. Hard work and long hours the right environment made my families life easier. And yes moving to a different state increased the odds of that happening. Stats are generalized. People who thrive don’t make excuses. They beat the odds. Others get mad and point to those statistics. I guess that’s you. My post pointed out how you helped people beat the odds. Somehow your panties got in a wad. Go figure. 
    • MrChips
      Road Master Active Suspension

      By MrChips · Posted

      Good question, I don't remember for sure but I believe it was the HD. I will check and get back to you.
    • Grumpy Bear
      OCI, not when but why?

      By Grumpy Bear · Posted

      Point of the post sir was that while both wages and cost are rising EVERYWHERE; the cost is rising faster EVERYWHERE than the ability to buy EVERYWHERE. We're not going down the location rabbit hole. I'm aware of what economic migration is. I've lived in four states including Texas.   It's what "Purchasing Power" means.   I'm not telling you what I think. I'm telling what the government, your government, data shows.   It wasn't an argument. It wasn't a suggestion. It was a statement of FACT. You are absolutely entitled to your own opinion. Your not entitled to your own facts. If you and I were, they wouldn't be facts.    fact /făkt/   noun Knowledge or information based on real occurrences. "an account based on fact; a blur of fact and fancy." Something demonstrated to exist or known to have existed. "Genetic engineering is now a fact. That Chaucer was a real person is an undisputed fact." A real occurrence; an event. "had to prove the facts of the case." The American Heritage® Dictionary of the English Language, 5th Edition • More at Wordnik   If you'd like to disagree call your Senator or Representative and let him know his departments are in error. But you and I? We are not doing this. 

  • GM-Trucks.com Clubs

  • Popular Contributors

×
×
  • Create New...