Boost Question
 

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?

Don't have a FP Gauge but when I'm WOT and let off it'l take a second to wind down so I imagine I have good RP. I just ordered a new MAP sensor i think that's the problem. I checked for codes and seen I'm getting overboost codes..at 23psi so I think it' a bad MAP sensor

You were told wrong, Smarty doesn't fool anything. It will map the boost tables to end of what the MAP sensor will read but that doesn't fool the engine. There are 2 ways you get over boost codes, the reading doesn't exist in the boost table or the WG limit is still on. Smarty should cover up the WG controller error but it won't always turn off the controller.

You probably should update your Smarty and reload it to see if anything changes if the MAP sensor does not work, change the AIT sensor in the TQ tube also as it is part of the MAP calculation. Next step will be to toss the oiled filter and get a good one in there that works and doesn't foul the system.,

Ok so I just installed a new MAP sensor, checked my AIT sensor (it was spotless and looks fine) and took it for a rip. Now I don't get an overboost code but it STILL only makes 23psi?? I was running SW3 with tq 1, tm 2, rp 2 and wastgate on. So I just put my truck back to stock and I am going to load SW6 on it tomorrow and see if my boost numbers change. I just apdated my smarty to POD REVO like a month ago too.

So today I loaded the trunk up with 3000lbs of water in the box and at WOT I could feel it every so slightly cut back.. I seen my boost spike at about 24psi then it quickly dropped off to like 22 then hung there. It feel like a de fuel but wasn't as soon or noticeble as before. And I never got an overboost code after doing that. So now I am thinking maybe I have a weak lift pump??