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2014 6.2L busted exhaust valve spring.

nitro882

By nitro882
in Troubleshooting & Recalls

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nitro882 Enthusiast

nitro882

Posted
Posted

I just got my truck back from the dealer today and found out that it had a busted exhaust valve spring on the #7 cylinder.

 

The back story is last week i pulled out of my driveway and the truck started shaking when accelerating and the motor was running terrible. The transmission also started downshifting really hard at the same time. Any time it dropped into first it shifted really hard. the MIL light was blinking and the traction control light was on solid. The DIC also had a message that said service stabilitrac. All these happened pretty much at the same time, needless to say i never got out of my neighborhood. Parked the truck and brought it to the dealer on Monday. When i fired it on Monday it drove fine for like 2 miles then same symptoms which eventually cleared by the time i got to the dealer bnut the mil light was on solid by then.

 

Truck was at the dealer for 2 days. They discovered a broken exhaust valve spring on #7. That would explain the misfire but it does not at all explain the transmission or stabilitrac messages. The tech said after the miss was fixed that all appears to be fine and he cannot find anything else wrong. I trust this dealers work as they have always done right by me in the past so i picked up the truck and its driving as it always has and everything appears to be fine.

 

The truck has 32K on the clock, is 100% stock and other than a couple of recalls for the transfer case programming the truck has only had one other issue. That was a failed injector on that same #7 cylinder about 10k mikes ago where the truck ran rough when cold but fine once warmed. I don't beat the hell out of my trucks so this motor has not been abused buy any stretch. I do tow with it but i don't flog it and i do maintain it.

 

Anyone have any ideas as to what went wrong? The valve spring could have simply been faulty and i can totally see the misfire being related to that, makes sense. The transmission and the really hard downshifts are really what puzzles me since they cant find anything wrong. No codes and after the misfire was fixed its gone. The tech did get to feel the downshift in the parking lot and even he was a little puzzled.

 

Other than the stretched timing chain i had to replace on my 97 vortech 350 after 300k this is the only other time i have had an internal part failure on a GM truck V8 and i have owned a few.

Colossus Senior Enthusiast

Colossus

Posted
Posted

Yes, but hasn't the 6.2L been out for awhile, or is it completely different in 2014 vs the GMT-900s?

Chris Senior Enthusiast

Chris

Posted
Posted

Yes, but hasn't the 6.2L been out for awhile, or is it completely different in 2014 vs the GMT-900s?

Different.
Daryl LBZ Senior Enthusiast

Daryl LBZ

Posted
Posted

The trans acting weird along with the stabilitrack, and traction control messages sounds about right. My Cruze had a misfire issue about a year ago, and it did the same thing. Dealer said it was due to it misfiring so bad. They fixed the issue, and the car has ran fine since.

Towerhog Enthusiast

Towerhog

Posted
Posted

These engine electronics are so interconnected that one problem may show up as something else. Case in point, disconnect the MAF sensor on my Raptor while changing the oil filter. Forgot to plug it back in. Started the truck and I got several messages about my stability control system. Shut it off, plugged the sensor in, restarted and all was back to normal. Weird how a MAF sensor can set off a stability control message.

HondaHawkGT Senior Enthusiast

HondaHawkGT

Posted
Posted

The transmission control module passes data back and forth with the engine control module. When your valve spring broke and the engine ran like crap, the data on engine performance received by the TCM caused it to try to adapt and in the process, acted strange.

TJay74 Senior Enthusiast

TJay74

Posted
Posted

All of the systems are linked, when the SES light tripped the system goes into limp home mode. That kills the stabilitrak system, as said once the power was off balance by losing a cylinder the transmission wont shift right as all of its shifts protocols are based off of torque input.

 

Cascading waterfall effect.

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