LB7: No boost/low power.

[White Duramax]

I am working on a buddies LB7 that has a low power problem. The motor was just put back in after having a piston replaced. No codes. Logging with efi it does not build more than 1 psi of boost total. Fuel pressure is right at desired, pulse seems to never be above 1100us. I have checked for boost leaks, checked intake system, checked turbo, all seems normal. One thing I did notice was that when checking data at idle, the calculated boost on efi shows 10.1 psi. Baro is 13.9-14.1 and map is about the same. MAf is around 5lbs at idle IIRC. I dont have another LB7 to compare to but my LLY shows calculated boost at 0 at an idle. Any advice? Thanks

 

[wdino73]

well for my 2 cents, check the waste gate to see if its broken, unhook the actuator if u and spin the linkage then bingo, also simple enough fuel filter...Good Luck...

 

[White Duramax]

Fuel filter is new. I forced the wastegate open and it would snap shut, I have not disconnected it to check.

 

[wdino73]

U need to disconnect it, it will move freely with the acutator off,, also what's the balance rates look like I have a reason for asking....

 

[White Duramax]

Injectors are all new about 1000 miles ago, I will check the rates anyways.

 

[DIESELMAFIAPER.LB7]

Any codes bad map sensor will do that at idle, i had a 01 lb7 doing the same thing

 

[White Duramax]

No codes currently, when I first hooked up to it, it had a couple map and maf codes but I cleared them and I they haven't came back yet.

 

[DIESELMAFIAPER.LB7]

Ceck the map sensor on it it made that 01 act stupid

 

[$Smokin_Duradog$]

Are you running the stock cal for the truck? If not did you run a script and forget to check that you ran it in the same properties standard or metric?

 

[White Duramax]

Bone stock, no tuning or programmer.

 

[TheBac]

MAF or boost sensor (on the intake next to the intake heater) could be broken/dirty? An electrical plug possibly not fully seated?

 

[White Duramax]

Found the problem, wastegate flap is spinning on the shaft. Thanks for the help!

 

[wdino73]

Glad u found the problem now the %$$%^^ of changing out the turbo....Good Luck

 

[03 lb7]

I lost boost at wot after what sounded like a hose blowing. Can’t find a boost leak anywhere. It’s got a fleece cheetah turbo, Bigger injectors, built trans, standard bolt ons, and a quadzilla stealth 2 programmer.

 

[2004LB7]

intercooler side wall crack