Hey guys, new to the forum and I just purchased an 05 Cummins with 180000kms that's in mint condition! It has an AFE intake, mbrp turbo back exhaust and the smarty s06 tuner. So I have an autometer pillar mounted boost gauge that is tapped in right before the intake elbow and no matter what I do I can only hit max 23psi Boost?? This is even with the wastgate turned off on my smarty. I don't notice any performance issues but I am just concerned reading how lots of people seem to him 26-30psi no problem with their trucks. I'm begging to thing my waste gate is possibly passing when I hit the low 20s just wondering if anyone had seen something like this before?

 

Could be wastegate or boost Leak- look for obvious tears/misaligned clamps. If you have a compressor and can pressure test it that’s ideal- if you can hold 10psi boost with pressure test you should be good with leaks and would point to wastegate

 

Thanks for the reply! I did some more research and seen that some 05s have plastic ends on the intercooler that leak so I'm gonna check all that out tomorrow night too.

 

So last night I checked for boost leaks and only found one small hose clamp leak. Truck still only made 23psi after fixing the leak and tightening all the other clamps. I also physically checked my waste gate and it moves nice and I can hear it tap closed so I know it is fine. So I am now lead to believe it is my solenoid that has failed. I am looking into either replacing the solenoid of installing a solenoid plug with an adjustable boost elbow but can anyone chime in on which would be the better option? Also not sure if an adjustable boost elbow would cause issues with my smarty or not?

 

Exhaust leak is another possibility, but i bet it's your wastegate solenoid. It's gotten weak and opening sooner then should.

 

Ok now I am EXTREMELY stumped... tonight I pinched off the air line from the solenoid to verify the solenoid has failed and even with no air supply to the waste gate I'm still only getting 23psi!?! I literally have no idea what is happening. My boost gauge seems to work fine, I probably should test and verify it but I cannot see that being the problem..

 

Get some wrire or SS cable ties and secure your WG closed. Take it for a run and see what you get

 

So I pressure tested everything again, verified my boost gauge works and I replaced my fuel filter. Haven't been able to drive it for a couple days been letting my afe air filter dry and oiled it last night so tonight I will take it for a spin and see if the fuel filter makes a difference, if it doesn't my next move will be to try wiring the wastgate shut. I didn't think I would have a fuel issue considering it smokes a little bit when making 23psi but I've been reading that some guys trucks smoke bad when there is a bad pump or filter so I thought changing the filter would be worth a try.

 

Ok now I'm getting somewhere but still need some ideas, wired my waste gate today and still only made 23psi but when I really stepped on it I noticed it de-fuel for the first time ever so I checked for codes and I got the overboost code but I still only made maybe at the absolute most 25psi. Why would my truck think 25psi is too much boost? That's with a smarty tune on and I was told Smartys will boost fool until the MAF is out of it operating parameters?

 

What does your RP hold WOT?