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Hard misfire. Super dirty injectors. Replaced. Still misfiring.

awk6898
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awk6898 Enthusiast

awk6898

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Well gents. $2700 spent on new fuel injectors and a top end de-carbon cleaning and I'm at a loss with my 2016 Silverado 1500 High Country. It has the 6.2 motor and 8 speed trans. 70k miles so out of the bumper to bumper but still within the 100k powertrain.

 

It started missing the other day. Only at certain rpms at first and then would go away when throttle was applied. Started having a blinking CEL (P0300) and traction control light when it was missing. Felt like going over rumble strips at 50mph. The whole truck shook... It got worse and then the next day it wouldn't go away with throttle. So it got taken into a Chevy dealer to have them diagnose and hopefully fix the problem.

 

Dealer said it was missing on cylinders 1+3. Plugs and wires are new (put on after the very first misfire incident because why not start with the cheapest possible fix first) . They stated they moved around coil packs to see if the problem stayed in 1+3, which it did, so they then said it must be the fuel injectors. They quoted $1200-ish to replace the injectors in 1+3 and I said let's just do all 8 while the motor is apart for another $1000ish. (Good call. Pics below)... Well, I went around and around with Chevys warranty people to no avail and so this is getting paid for out of pocket...

 

I got the call today to come pick up the truck and everything seems fine and dandy after the new injectors... Til 15 miles down the road and the miss comes back. Same exact symptoms. Can't throttle out. Turn the truck off and on. Misfiring at idle. Etc... Call up a tow truck and back off to the dealer I go...

 

The service advisor has been great throughout and I believe is a regular on this forum. But I'm at a loss for what to do now. $2700 is a lot of money to put into a truck for the problem to not be fixed after they stated "The fuel injectors are definitely the problem".

 

Any ideas?

 

65065d012131237702566607ebc07d63.jpge9f689517d903407883eef990eb510b6.jpg1433666ac45b013626de60f51cdea155.jpg

 

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awk6898 Enthusiast

awk6898

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Also. I just bought the truck 2 months ago. I've only ran premium through it, but can't say for certain what the previous owner used... Either way, I can't believe this is "normal" for an injector with 70k miles and even the WORST gas you can find on the market.

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Paintor Enthusiast

Paintor

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https://www.gm-trucks.com/forums/topic/209617-2018-62l-leaking-coolant-from-head/

 

Common problem. Porous poor quality head castings. Eating yer coolant or oil. Sux you replaced the injectors for nothing.

 

Dealer should have known this.

 

B.O.A.T. stands for ‘Bout another thousand...

 

I name yer truck B.O.T.T., ‘Bout another three thousand

 

Edited by Paintor
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Racindave Enthusiast

Racindave

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15 hours ago, awk6898 said:

 

Well gents. $2700 spent on new fuel injectors and a top end de-carbon cleaning and I'm at a loss with my 2016 Silverado 1500 High Country. It has the 6.2 motor and 8 speed trans. 70k miles so out of the bumper to bumper but still within the 100k powertrain.

 

It started missing the other day. Only at certain rpms at first and then would go away when throttle was applied. Started having a blinking CEL (P0300) and traction control light when it was missing. Felt like going over rumble strips at 50mph. The whole truck shook... It got worse and then the next day it wouldn't go away with throttle. So it got taken into a Chevy dealer to have them diagnose and hopefully fix the problem.

 

Dealer said it was missing on cylinders 1+3. Plugs and wires are new (put on after the very first misfire incident because why not start with the cheapest possible fix first) . They stated they moved around coil packs to see if the problem stayed in 1+3, which it did, so they then said it must be the fuel injectors. They quoted $1200-ish to replace the injectors in 1+3 and I said let's just do all 8 while the motor is apart for another $1000ish. (Good call. Pics below)... Well, I went around and around with Chevys warranty people to no avail and so this is getting paid for out of pocket...

 

I got the call today to come pick up the truck and everything seems fine and dandy after the new injectors... Til 15 miles down the road and the miss comes back. Same exact symptoms. Can't throttle out. Turn the truck off and on. Misfiring at idle. Etc... Call up a tow truck and back off to the dealer I go...

 

The service advisor has been great throughout and I believe is a regular on this forum. But I'm at a loss for what to do now. $2700 is a lot of money to put into a truck for the problem to not be fixed after they stated "The fuel injectors are definitely the problem".

 

Any ideas?

 

65065d012131237702566607ebc07d63.jpge9f689517d903407883eef990eb510b6.jpg1433666ac45b013626de60f51cdea155.jpg

 

Sent from my SM-G973U using Tapatalk

 

 

 

That’s nasty 

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awk6898 Enthusiast

awk6898

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Dealer called and said they thought it just needed another top end cleaning. That "maybe it was so dirty that the first cleaning loosened up something that broke free when I picked it up from them and started driving home and it caused the truck to begin missing again..." So they did another cleaning (free of charge) and did an "extended test drive" with no problems other than the motor is throwing a code that apparently says it needs a new catalytic converter. They're replacing the cat under warranty tomorrow and will then do a 'leak down' test to make sure everything is tight internally.

I'm still having a hard time believing that much gunk and carbon buildup after only 70k miles is "normal" for a DI engine and that getting the engine de-carb cleaning every 30k miles is "standard maintenance". Just sounds like a poor motor design that they're trying to cover up... [emoji3166]

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Sierra Dan Senior Enthusiast

Sierra Dan

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Looks like the previous owner never changed the oil or ran it on a 2 cycle gas /oil mixture!  Sheesh.

Momma always said life is like a used vehicle....... Never know what your'e gonna get.

Did you recieve a Carfax or other report on the truck to see if it had been taken in for any kind of past services good or bad?

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  • 2 weeks later...
awk6898 Enthusiast

awk6898

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Update. Got the truck back and no more misfiring. At least, no more OBVIOUS misfire... The truck runs rough now. You can feel it predominantly at idle. It almost feels like a cammed up sportscar except this is a pickup with a stock cam. Also it now magically has a pretty strong vibration while being driven that it never had before. [emoji58][emoji58][emoji58]

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