Low Turbo boost

My 1999 12,7 only gets to 10-15 max. Real dead at lower RPMs. I’m guessing it’s the sensor. Does that sound right? Same symptoms as when my last Truck had that problem. I didn’t have a boost gauge though. Changed fuel filters didn’t help. No codes. Don’t recall any codes last time on last Truck.

 

Yeah it’s a Detroit. I have a homemade leak tester. Everything’s relatively new. I just wondered how much boost if any the turbo produces, if the sensor is bad. Seems like it has to produce some since it’s spinning. I’m going to unplug it, and see if boost is the same. Just don’t want to buy a sensor if I don’t need it. I don’t know how the sensor controls the turbo, since the turbos all mechanical. Last time I changed one, a bolt broke off in the manifold. It’s a common thing. Considering it’s never been changed. Might be a problem. I’ll use some heat and PB blaster this time.

 

Update. Bought a turbo sensor online from Lab works for $20. (A friend commented I should have bought 2) Lol. Anyways same problem. Found a leak in the big hose from cac to manifold. So obvious, yet I missed it. Oh well at l at least didn’t pay $160 from the Dealer. Now I have a spare boost sensor. New hose is $375, on backorder. Plan on a 4” steel tube with 2 new boots. Meanwhile it’s duct taped. Yep. Also changed all the fuel lines. Been postponing it forever. Suspect it’s been sucking air causing it to sputter sometimes. Had all kinds of problems after changing them, kept losing prime, replaced o rings in check valve, and stretched the spring a bit. No help. Noticed a lot of air bubbles in tanks. I had to redo a couple of the fuel lines. They were sucking air, and bleeding down within 30 minutes. Finally got everything sealed up good. Seems to be running pretty good now. Didn’t hurt the check valve stretching the spring out. It’s working good. Holding prime over night. Intermittent sputtering issue might be solved. I hate to mention it and jinx myself. Still have a very small amount of bubbles in tank. Will soon know for sure. Hasn’t sputtered in 1800 miles so far. Trying to keep the boost below 20 lbs. That’s when the duct tape blows out. Lol.

 

I’ll do one after I fix the major leak. Cac is fairly new. 200k miles. Avtek brand. Anyway Thanks. You were right about the cause.

 

It’s on the cold side. One big 4” rubber hose about 3 ft long. $387 at Dealer. Need to get a 4” pipe. Pvc aluminum, anything. Cut ends off rubber hose for now. Eventually get a formed 4” aluminum pipe. Use the ones you’re talking about. I carry one of those. Have blown them before. Have blown the 1” compressor hose once. Never this big original rubber hose. Be better w/aluminum pipe. Not paying $400. Lol. $88 online fits Cascadia. Couldn’t find one for FLD. Maybe get the part# look again. I’ll figure something out.