Need honest help!

[Colton Campo]

This will be my first post, but I've always use the site as a valuable  resource. Thank you for that 

  

Vehicle is 2014 GMC Sierra 6.2l

 

The truck sat at the dealership for 3 months and my problem still exist.

 

The problem- multiple misfire, fuel trims all over the place . 

Parts replaced(all gm direct replacement)-

(dealer suggested) -new transmission, new cat converter. Cost 8k 

(Self installed) -plugs, wires, MAF sensor, all O2 sensors. Thermostat 

 

Where I'm at now.  Picked up my vehicle for the 3rd time from the dealership. Dealership said swaped wires and misfire cleared. Suggested a near air box and MAF sensor. Quoted @ $750 . Went and brought the vehicle home to work on it myself.  Pulled left (passenger side) fuel rail. Misfire was indicated number 4 cylinder. The last injector "pocket" looked to have orange fluid pooled at the bottom. Got the injector out to find it full of "coking" and it was wet. Coolant is orange and the reservoir has seem to have lost some level. Pictures attached

 

 

My question- What's my next move ?

Did the injector have a seal problem?

Clean and install new injectors ( already have them on hand) ? 

Dig deeper and replace head gasket?

 

 

[Jsdirt]

First off, stay away from dealers. If you're going to have someone else work on it you'll need to find a local garage with a good reputation. They'll get you going for a fraction of what any dealer will charge, and in much less time in most cases.

 

Without knowing what the engine was doing prior (in the form of scan tool data) I haven't the slightest clue what you should be doing or where you should go from here. If the fuel trims were all over the place, I'd be looking at o2 sensors & wiring first.  I do know that any time those injectors are removed you have to replace the lines connecting to them as an assembly - they're a one-time torque piece, and that's it. If you reuse them, you'll have issues.

 

I'd also want to know what's in the fuel tank. The lot tech could've dumped about anything in the tank thinking it was fuel. Could've grabbed the washer fluid hose instead of the gasoline hose. Literally anything is possible today.

 

Head gaskets usually last a good amount of time on these engines unless the thing was run out of coolant or Chernobyl'ed for some other reason.

[Colton Campo]

Thanks for the quick reply man. Yes, I have the replacement lines. The O2 sensors were tracking but the passenger side pegged out with the misfire. My first thought was the sensor. Checked resistance and changed just for the hell of it. The incomplete burn makes a lot of sense with all of the carbon and sludge build up.

[Jsdirt]

Just remembered hearing a fellow tech say that these injectors are highly failure prone. That could very well be your issue.