Hey guys, i was out in my brother's truck last night its a 2012 sierra with a stock engine "5.3" with a 76mm turbo running 9-10 psi. we were dialing it in from about a week now it was perfectly fine. This time he was driving so i told him to keep an eye on the boost gauge and ill look at the AFR. he rolled into the throttle in 3rd and a few seconds later the afr spiked to 14.0 i told him to let off and stop on the side of the road he told me the boost spiked to 20 psi, i opened the door and the truck was smoking from the exhaust and there was a tick coming from the engine, what caused this sudden overboost i have no idea. we are going to open it up tonight to see whats up, we have another junkyard 5.3 around so we will probably be swapping it in. here is a video i took don't know if the smoke coming from the exhaust is visible.

 

That sucks, and its wierd you got such a high boost spike randomly. Wastegate issue? Are you running a boost controller?

Definitely sounds hurt

 

Time for a compression test.

 

Ruh roh.....definitely bottom end

 

Hate hearing these kinda stories, never fun.


I am not to familiar with turbos and exactly how their system works but it seems like over boosting is more common than I though (just an assessment from lots of posts on here). Is there a fail safe or something to prevent this from happening? If you are say 2 bar SD or something can you have the tune shut it down if it goes over say "x" boost level?

 

Yes, but only with a 2 bar OS meant for boost. There is a boost cutoff but it has to be an upgraded OS.

 

Gotcha and figured as much. Will be looking into this once I get my 04 built. Seems like a nice safety net

 

Jeez Ahmad, remind me never to let you tune my truck

That sucks to see though. Post up what you find!

 

well turns out the shop installed the line in the top port on the WG instead of the bottom... nice we already found another junkyard 5.3 we will be done with the swap in a couple of days this time ill keep an eye on everything. glad it wasn't my 416 LOL

 

NOOOOOOOOOOO!!!!!!!!!!!! damn man sucks. waste gate issue? u running maf or os