cm870 ISX Turbo Screech Monroe/Charlote, NC

[Bengy88]

(04-08-2023 )Magnum1 Wrote:  Thank you everyone for your replies. If I will come to the conclusion that it is either vgt or controller - it'll have stationary turbo.

It’s your truck so I’m not gonna tell you what to do with it but take what I’m about to tell you and do what you want with it.

When I first started doing this shi#t I was all in on vgt deletes, who wouldn’t want to buy a $2000 kit and put a simpler, cheaper turbo in place of a $3500-4000 turbo? Hell it even makes 45psi of boost right? Not to mention the entire passenger side of your engine looks nice and clean…… well after about a year I started realizing every truck that my customers wanted a vgt delete done on had cracked a head, wasn’t long after that came the excessive blowby from collapsing rings, oil consumption etc. it was a chain reaction with all of these trucks….. not just one but every one. Not only that but the engine brakes were weak and there was extreme turbo lag in lower rpm’s. (The shi#t nobody tells you about their engines after they have made this mistake). Well I took one of these trucks “my brothers” and I played with making it as dependable as I possibly could. I lowered torque, set rpm limiters, did everything I could think of to keep the stress down….. that was 2 years ago. I’m now tearing the engine down to replace a cracked piston.

Isx engines can not safely handle these turbos. 45psi of boost is entirely too much. You can no longer control fuel/air mixture properly. Usually the exhaust gas back pressure sensor will be deleted, this monitors missfire conditions, you actually loose power from too much boost, loss of engine brake performance, lower fuel mileage, cannot properly tune, the list goes on. So why would you want to do this to a truck? You save 2000$ that cost you 25-30,000$. Saving a penny just to spend a dollar huh? This isn’t a 14l Detroit or a twin turbo cat where you can get away with making changes like this and not seeing an issue from it. These engines are far more complex and sensitive to doing stupid shi#t to.

Instead of trying to beat around the actual problem why not ask “well how come when I move that little arm the squeal stops”? It’s because that little arm controls the vanes in the turbo which controls boost which in turn increases or decreases pressure in the intake, manifold, turbo, and exhaust. When you move that little arm the pressure is decreasing. Kind of like when you whistle if you don’t blow quiet as hard the whistle will go away. This is what’s happening with your truck.

Say you pull your turbo, pull your manifold, check for blown gaskets, replace them, disassemble your turbo just to see that nothing is wrong with it, reassemble your turbo, (rawze has videos on this I believe), and reassemble your truck. If the noise stops you have fixed it, if you find an issue in the turbo you can fix it… either way the problem will be fixed and worse case scenario you loose a couple hours of labor and a gasket. In 18 years the absolute only thing I’ve heard cause that sound is turbo gaskets/cracks and exhaust manifold or egr gaskets. Not to mention if you scroll the comments in the video you sent you will see where people were fixing this problem by replacing gaskets. We are here to help you but if you won’t take the advice given then there is absolutely nothing else this forum will do for you. Good luck in figuring the problem out.