No boost

japper

New member
I would appreciate if some mechanics could give me some pointers/directions. I don't have the van with me, customer has to drive it and I can see it for limited time.

Originaly it came with DPF soot too high for regen, I replaced it with another used DPF. Couple months later he came back with no boost.
This time with code 2623 charge air system- offset drift at idle. I replaced MAP/boost sensor, inspected the turbo vanes and the orange gasket, tested with smoke leak detector and repaired leaky air tube connection (O-ring) below air filter box on right. After that the code was gone but still no boost. At idle the reading is about 800-900 hpa and under full load only goes up to 1290 hpa and charge pressure positioner is at 5% the whole time.
With my scan tool I can actuate the positioner at raised idle to 90% and visually confirm the positioner linkage move freely and charge hoses building pressure peaking at 1290 hpa. I did not find any other leaks not even cracked intercooler hoses. I have removed and cleaned EGR valve (was working fine and it wasn't that dirty).
Currently it has no codes and van drives ok except lack of power. I will try record data next time.
 

lindenengineering

Well-known member
Before doing anything pull out the EGR cooler--bet you its choked!
You owe me a bottle of Malbec if I am right'!:thumbup:

Take a fresh look at your intake system smoking the tracts. I have many a leak at the throttle body jointer and the 5mm x90 mm through bolt missing.

Once running you may have to take a close look at the exhaust system thermo couples and the O2 sensor.
Dennis
 
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japper

New member
I think I found the gremlin. Atmospheric pressure sensor is reading 700 hpa at all times and based on my MB Star/WIS, the atmospheric sensor and manifold pressure sensor should be within 30hpa from each other at Idle or key on. I just didn't pay attention to the atmospheric sensor readings, until I read a post about no boost and fix by replacing the atmospheric/air filter sensor.I will update the results in few days, when I'll have the van here.
 

japper

New member
So finally the van is boosting again!!:bounce:
I noticed under different data block the exhaust pressure sensor was reading only 700 Hpa same as Baro/atmospheric sensor, it should be very close to Boost pressure and intake air pressure between 950-1100 Hpa in Midwest.
Replaced the plastic exhaust pressure sensor with 2 nipples and 3 wire connector.
First I had 0 Hpa on exhaust pressure even after small test drive and couple resets and adapts with still no boost condition. But after giving up for that day, the customer called me back after 20 mins all excited that he's boosting again! :cheers::rad:
That tells me how important longer test drives are with these vans!
 

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