Misfire & Carbon deposit help

[PPV_2018]

‘afternoon fellas,

When i got my PPV last year, i changed the plugs and wires within the first couple weeks — And the plugs were rough when i pulled them originally, they looked bad and had gaps all over the place. Tbh i have no idea how it ran so smooth at the time. So i changed the plugs and wires with AC Delco.

Fast forward to now, truck ran smooth as butter until recently truck developed a misfire randomly on the highway. I felt reduced power and the engine was shaking as common when you’ve got misfires, but no code.

Limped it home and it took about 20 minutes of idling in the driveway before i finally got it to set a CEL - Cylinder 1 Misfire detected.

Pulled plug for cyl 1 and it was pretty rough looking, with thick carbon deposit coating the upper portion and the insulator.

Pulled plug for cyl 2 and it also had some carbon deposits

(Cyl 1 left, cyl 2 right)

I now have to assume all the plugs probably look like this to some degree. Looking for some guidance on how to proceed.

wondering if this could be related to DI buildup ?

 

[lt1gmc]

Not DI buildup, that would be on the intake valve. Could be leaking injector, or bad lifter/cam lobe which is what I found on mine. Not necessarily with tick. Bad or no spark and the plug would be washed clean.

 

[PPV_2018]

Not DI buildup, that would be on the intake valve. Could be leaking injector, or bad lifter/cam lobe which is what I found on mine. Not necessarily with tick. Bad or no spark and the plug would be washed clean.

Thanks for the reply.

I’m aware that the DI buildup would be on the intake valves, but was wondering if it was excessive enough, could it be causing the fouling on the plugs

According to a TSB i found, this seems like it could be plausible.

If it was a leaking injector, wouldn’t only the one plug be fouled, because as seen in the photo’s, cyl#2 is starting to get buildup as well albeit not as bad. Keep in mind, these plugs all have less than 6000 miles on them.

 

[lt1gmc]

It would take a lot of oil coming thru the intake to foul the plugs. Pull the intake hose off the throttle body to see if there is a lot of oil in there from the PCV. Besides, the black plug is way worse. The smooth black on the plug insulator looks like fuel residue to me.

 

[PPV_2018]

Air intake tube and throttle body are squeaky clean

truck engine sounds like a damn Powerstroke now.

Lifter failure ?

 

[Doubeleive]

Air intake tube and throttle body are squeaky clean

truck engine sounds like a damn Powerstroke now.

Lifter failure ?

probably needs a good injection service, cleaning, start using 5-30 instead of 0-20.
run a scanner on it and look at the live engine data for more information.

 

[PPV_2018]

Here’s a video for referance

Already using 5w30

Scanner data:

Engine cold:

ShortFT1: 0.0%
LongFT1: -0.8%
ShortFT2: 0.0%
LongFT2: -0.8%
MAP: 5.8 psi

Engine hot:

ShortFT1: 0.0%
LongFT1: -18.0%
ShortFT2: 0.0%
LongFT2: -7.0%
MAP: 5.8 psi

 

[Doubeleive]

Here’s a video for referance

Already using 5w30

Scanner data:

Engine cold:

ShortFT1: 0.0%
LongFT1: -0.8%
ShortFT2: 0.0%
LongFT2: -0.8%
MAP: 5.8 psi

Engine hot:

ShortFT1: 0.0%
LongFT1: -18.0%
ShortFT2: 0.0%
LongFT2: -7.0%
MAP: 5.8 psi

you need a scanner so you can troubleshoot first by swapping plugs, wires and coils to see if the problem follows

 

[PPV_2018]

Guess i shoulda mentioned that video was taken after installing a brand new GM genuine coil and spark plug on the misfiring cylinder.

 

[OR VietVet]

To start with, I see nothing wrong with #2 spark plug. How much time/mileage on new plugs?

 

[PPV_2018]

To start with, I see nothing wrong with #2 spark plug. How much time/mileage on new plugs?

Roughly <6000 miles. ( live in the city so it takes longer to accumulate mileage)

 

[OR VietVet]

Looks like fuel delivery problem on #1.

 

[Doubeleive]

Guess i shoulda mentioned that video was taken after installing a brand new GM genuine coil and spark plug on the misfiring cylinder.

could be the injector/s just had all of the ones on the wifes rig replaced last week under special gm coverage.
but there under the intake so.... no easy task to test
it doesn't sound like lifters to me

 

[Fless]

could be the injector/s just had all of the ones on the wifes rig replaced last week under special gm coverage.
but there under the intake so.... no easy task to test
it doesn't sound like lifters to me

An injector balance test is not intrusive and would indicate if an injector is mis-metering fuel.

 

[Doubeleive]

An injector balance test is not intrusive and would indicate if an injector is mis-metering fuel.

IF, you have a scanner or tool to do it

 

[Fless]

IF, you have a scanner or tool to do it

Parkland College in Champaign, IL. When I lived in the area I had a girlfriend once who went there (not in the automotive section).

I own a few acres of inherited prime farmland in the adjacent county (Vermilion). The white corn goes to Frito-Lay and I'm not sure where the soybeans go, except maybe to gm wiring harness insulation. Just kidding, it's all food grade.

 

[Geotrash]

Here’s a video for referance

Already using 5w30

Scanner data:

Engine cold:

ShortFT1: 0.0%
LongFT1: -0.8%
ShortFT2: 0.0%
LongFT2: -0.8%
MAP: 5.8 psi

Engine hot:

ShortFT1: 0.0%
LongFT1: -18.0%
ShortFT2: 0.0%
LongFT2: -7.0%
MAP: 5.8 psi

I dunno, gents. That sure sounds like a collapsed lifter to me.

 

[RET423]

Times 2 on the sound being a collapsed lifter, that's what it sounds like to me

 

[NELLY1947]

‘afternoon fellas,

When i got my PPV last year, i changed the plugs and wires within the first couple weeks — And the plugs were rough when i pulled them originally, they looked bad and had gaps all over the place. Tbh i have no idea how it ran so smooth at the time. So i changed the plugs and wires with AC Delco.

Fast forward to now, truck ran smooth as butter until recently truck developed a misfire randomly on the highway. I felt reduced power and the engine was shaking as common when you’ve got misfires, but no code.

Limped it home and it took about 20 minutes of idling in the driveway before i finally got it to set a CEL - Cylinder 1 Misfire detected.

Pulled plug for cyl 1 and it was pretty rough looking, with thick carbon deposit coating the upper portion and the insulator.

View attachment 458218

Pulled plug for cyl 2 and it also had some carbon deposits

(Cyl 1 left, cyl 2 right)
View attachment 458219

I now have to assume all the plugs probably look like this to some degree. Looking for some guidance on how to proceed.

wondering if this could be related to DI buildup ?

Just a dumb possibility .....is it possible the #1 cyl is one of the cylenders that shuts down on the hiway , when under little load is detected???

 

[Doubeleive]

Just a dumb possibility .....is it possible the #1 cyl is one of the cylenders that shuts down on the hiway , when under little load is detected???

(1,7,6 and 4)