engine surge

[emstech]

i have a 2006 e-350 with 6.0 powerstroke. it is an ambulance with 155,000 miles on it. it has an engine surge as soon as you start moving and has it till you get back to idle. thought it was fuel but changed upper fuel filter housing,cleaned lines and replaced banjo bolts in both heads,inspected fuel tank,and took a sot with a fuel pump. the truck is not setting any codes. test drove with ids numerous times and recording snapshot when problem is at its worst and not see anything wrong. i feel like it is the turbo vanes stuck but i am relatively new to powerstrke issues. i worked for gm for 22 years. i just need some direction cause i am at a wall. HELP !!!!!

[WEWILLE]

Theres a bunch of stuff you can check, but start with removing the egr valve and see how dirty it is. Try cleaning it and retest. Post up what you find, if the egr valve is clean then let us know and we will guide you from there. Ambulances tend to idle alot so most likely you will find a nasty egr valve.

[emstech]

the egr valve is new and the intake has been cleaned. all wiring is good condition there is no rub spots in it. the oil pressure system hi and low show no signs of fluctuation and are at proper operating specs. i inherited this from another tech in the shop.

[WEWILLE]

What color is the smoke? What is the ICP voltage when it surges? Graph the EBP and MAP sensors on a WOT accel. The EBP should be about 5-10 psi more than the map pressure. Both sensors should increase smoothly, if they dont this can be an indicator of stuck vanes in the turbo. What does your cylinder power balance graphs look like on the IDS when it is surging? Is it possible it is missing? Check it out, let me know what you find.

[forddieseldoctor]

How about your EBP tube and sensor? How bout your map sensor and hose?

[TowBoss]

Maybe it's the ICP sensor.....

[emstech]

thanks for the responses they were all good but all tested good. i test drove another vehicle that is working properly and compared snapshots. i found that the vgt was fluctuating greatly so replaced the vgt actuator and for safety sake installed a new pigtail. the truck ran great. keep in mind this was setting no dtc's , it was not smoking or even running to bad. the surge felt like a stopped up fuel filter on a gas engine. it did it starting at 1000 rpm and still surged at steady speeds and did not matter if it was light throttle take off or wide open. thanks again to all who responded with things to check.