The Diesel Stop banner

Black Smoke and low power at low RPM

8411 Views 25 Replies 7 Participants Last post by  JazzBass
This has been on going for a couple of summers now. When things get hot, pulling away from a stop or accelerating in OD, the truck smokes and feels quite lazy and the boost seems to lag what my foot is requesting. The heavier the load the worse it gets and the hotter the outside temp the worse. It basically goes away in the winter. It will do it when bobtailing after a long run on the freeway then come to a stop sign on an off ramp and start to pull away.

EBP, IPR & ICP have all been replaced recently as has the FICM and 8 injectors. I just replaced the hose running to the MAP sensor before the last trip and removed the EBP to recheck and clean, it was in good shape. The EGR was replaced last summer but didn't fix it, it has been cleaned several times since. The truck runs like it did when it was brand new until this issue happens then it's fine again once the truck cools down.

Once back in April, in the mid west I was pulling into a 40 mph headwind mostly uphill and working the tail off the truck, the boost would wail up to the 30 psi mark, I would lift, it would race down to the bottom then get stuck at about 5 PSI and I would have trouble picking up speed, the truck would drop a gear, RPM up then it would start working fine again.

I've had the turbo off twice and taken it to a diesel shop, they've opened it up, lubricated it then handed it back telling me everything looks good.

I also data logged yesterday but it was just while I was rolling along without a smoking issue. I have attached a couple files. I used the CTS2, not as thorough as my AE but much easier to do spur of the moment. Yesterday, I was on secondary 2 lane roads later in the day which I seldom drive on and pulling away from stop lights with trailer, it smoked heavily until it got rolling then nice and clean.

I even passed the snap test for emissions testing a few days ago.

I have a 2 hour run tomorrow morning with a trailer on but it will be fairly cool and and mostly 4 lane high speed but I will data log again if it starts smoking.

I'm ready to order a brand new OEM turbo (Garrett has new ones now...brand new) but I would like to know if there is anything else I can check first like maybe the VGT solenoid, is there a test for it?

Any ideas please before I just throw a turbo at it?



See less See more
1 - 1 of 26 Posts
I cant see a turbocharger being directly affected by ambient temperature. Not at all. I would cancel your order for the moment until you can prove you actually need a turbo. I am an expert however the data you are collecting is for the most part, garbage and will not help identify the cause of your performance problems. Two main areas that will cause low boost numbers is the air management system and fuel delivery. We can get a better look at the air management system by looking at the following parameters (to start with) from a dead stop with a FULL THROTTLE acceleration or when the condition is present:

  • Accelerator Pedal
  • Barometric Pressure
  • EGR Valve - Duty Cycle
  • EGR Valve position - volts
  • Exhaust Back Pressure
  • IAT-1
  • IAT-2
  • Manifold Absolute Pressure
  • RPM
  • VGT Duty Cycle
See less See more
1 - 1 of 26 Posts