New head, new tune, now no boost
04-28-2020, (Subject: New head, new tune, now no boost ) 
Post: #1
New head, new tune, now no boost
I’m having some trouble with a de-mandated cm871 in an 08 Peterbilt that has kinda been a problem child for years. Truck was bought at an auction about 10 years ago already de-mandated and ran great, but i guess it’s always had problems keeping heads on it, and it’s gone through the original engine and is currently on a cummins recon engine. I’ve only been around it about 6 months, 6 months ago I put a head gasket on it, and just about 2 weeks ago it cracked the head. We decided to get the ecm re-tuned since it hasn’t been since purchase and we suspect the tune to be too hard on the engine.. After replacing the head, front bank timing actuator(actuator was replaced due to a white smoke haze at idle that followed to the rear bank when swapped around) and a leaking CAC, truck still makes very low boost, like the VGT isn’t doing anything. We called our tuning company and told them what was up, turned out they loaded a non-vgt tune onto our ecm. They logged in remotely and put the proper tune on, but it still seems to be doing the same thing. I’ve had the VGT apart, it sweeps side to side freely, the actuator calibrated and installed properly, and I can hear it sweep back and forth on a key cycle like it’s moving properly. I pulled the valve cover and ran back through my overhead just to double check, it’s all perfectly in spec still. I’m starting to lean towards our tuning still being messed up. VGT position on instie moves with the throttle, commanded and actual stay very close if not even the whole time. Driving it ripping through the gears full throttle it won’t top 17lbs of boost, throws a good bit of black smoke, and upon opening the hood after a short drive you can tell the exhaust and turbo are getting much hotter than they should be.

Anyone have any insight into what else I can look at? I’m gonna get back into contact with tuning but I know they at least loaded a different calibration in, because before when unplugging the EBP sensor I would not set a code, and now it does. That’s how they had us check to see if they gave us the wrong tuning.
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New head, new tune, now no boost - Svohlin1 - 04-28-2020



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