2009 Hino 285 no/intermitten boost 40mph to 50 mph

[alasich]

i have a 2009 hino with a 268 j08e-tv with 190000 miles and allision trans

problem is when motor is cold, the truck will go 0-75mph no problem.

after about 20 minutes of driving or motor warm. truck will go 0-40mph full boost, shift into 4th, then the motor starts to build boost, dumps boost, builds, dumps, and slowly accelerates to 50mph. once the turbo smartens up, grabs last gear and then goes 50-75mph no problem, and holds boost pressure no problem. can repeat problem by slowing back to 40mph and going full throttle. always between these speeds

things have checked. egr, intake valve are all opening and closing properly (visually with linkages). command opening and actual opening with data log are same. requested fuel rail pressure, and actual fuel rail pressure same (or very close), tps does not drop/dip when having issues and holds steady

tested scv at idle as per bullitien, and only have a fluctuation of 89mA with a average of 1650mA

charge air piping, boots, cooler pressure tested and good

truck does have a intermittent p0088, no other codes and will be changing sensor, but i dont believe that to be the problem as the light only come on sometimes,

fresh fuel filters, clean tanks. its seems to be something once engine gets to temp or after so much run time

transmission serviced with new filters and oil

best place to start? i dont want to throw parts cannon, but nothing seems to be jumping at me that is causing issue

 

[alasich]

update

i drilled holes in the ITV as greasytshirt mentions in many other posts. now the truck doesnt seem to have a issue with it loosing boost and power.

but i did notice when it was doing a burn while driving it lost all power and boost and would only go 50mph. once burn was complete it went back to full power.

i believe the ITV has a weak motor and cant hold middle positions and flutters open and closed,

going to order a new one and see if that helps

 

[greasytshirt]

I'd inspect the turbo and see if there's any binding if you put a little side pressure on the shaft while spinning it by hand. Can you get into system protection data? DPR inlet temperature much higher than outlet can indicate an airflow problem.