2973 help

[dieseltek8080]

So I Have been racking my brain on this one. Any help is appreciated.
2008 871 isx.

customer brought in with complaint of power surge. like on off switch throttle. Truck has 500k on it and has owned for 150k. Been to countless parts changers and wound up at door. multiple times has new tps and imap sensors. tps was easy as I found signal wire to sensor 2 broken causing 0 to 100% as soon as throttle was touched.

now code 2973 has been a chore. found CAC cooler broken at multiple tubes and went from 30 psi to zero in less than 2 seconds during pressure test. has new CAC now. No more cold side leaks. now mind you this truck has been EGR and DPF tuned by another shop to try to repair this truck. So I am a bit in dark as to who tuned it and physical mods done. All I know for sure is egr cooler still present and flows coolant per infared temps but exhaust part is cold and has block off plate sandwhiched where egr elbow meets intake..

1 imap is new from less than 100 miles and have previous supposed failed sensor... no soot because no egr and all readings same between the 2.

2 baro reads within 1 hg of local

3ohmed turbo speed sensor. 890 ohms.

4 checked air filter.


now data on snapshot

exhaust pressure 129.17 Seems legit for 100% throttle

1725 rpm

exh calc temp 298 pyro around 800

imap temp 62 degrees
imap press 52.3


89%load

vnt 33 % closed (measured)

turbo speed 99242



this truck drops off between 1500 and 1750 in high gears. noticeable surge in power. after 1750 clears up.

built 38 pounds of boost until surge and drops to 28 to 30 and stays there until next shift.



What am I overlooking? I am installing sight glass on return to verify good orings but the code is generic. its sayin pressure is above or below forcasted pressure for current conditions but I don't know if its high or low... Any help is appreciated. need any more info from snap shot just ask.


cheers