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+--- Thread: No boost in first few gears (/showthread.php?tid=7028)
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No boost in first few gears - tdawg - 02-09-2021
I have a CM870 that sometimes starting off will shutter and pour black smoke in the first 4 gears and then takes off and runs normal. Most of the time it takes off normal and other times it messes up. Replaced the electronic and air actuators to turbo but no change. The way it shutters it seems like an electronic or timing issue?
RE: No boost in first few gears - Rawze - 02-10-2021
maybe disconnect the air actuator and see if the turbo arm is hanging up?.
RE: No boost in first few gears - tdawg - 02-10-2021
I put a new one on and checked to make sure nothing was hanging up on the turbo but still doing it. Any way the fuel cut off could be bad?
RE: No boost in first few gears - tree98 - 02-10-2021
Is the electronic actuator a genuine cummins ? The cheap aftermarket remans are usually junk.
RE: No boost in first few gears - tdawg - 02-11-2021
all cummins parts and then i ran the fan while i idle and through the lower gears and it stopped doing it. Air to turbo control is straight off tank with nothing else attached. only thing i can think is belt slipping on water pump and turbo getting to hot.
RE: No boost in first few gears - Mr Hagg - 02-11-2021
Running the fan means your not using air. May want to check fan hub make sure its not leaking could be its robbing air from air valve to turbo...
RE: No boost in first few gears - tdawg - 02-12-2021
(02-11-2021 )Mr Hagg Wrote: Running the fan means your not using air. May want to check fan hub make sure its not leaking could be its robbing air from air valve to turbo...
air is isolated with 3/8 airline strait from tank to control valve. That tank is always over 100psi.
RE: No boost in first few gears - tree98 - 02-12-2021
I think you said you replaced the electronic actuator and the air actuator, maybe one is defective?? put a gopro under the hood and go for a drive, see if the action looks erratic??
RE: No boost in first few gears - Chamberpains - 02-12-2021
Is this the same engine you've posted about previously with low boost problems? Is it the same engine you swapped out of an international and put in a Volvo? Did you have the programming checked by an if the pro's from here? Have you physically checked the turbo itself and the armature for the VG ring? Does it move smoothly (a little squeaky movement is okay) with out any hang ups?