it sounds like overboost and its defueling. either bad/stuck wastegate or bad boost sensor i believe

 

obdII doesnt run through OPS.

 

Hello,,
ok the oil prerssure is around 40 at idle and little over 60 highway speed. one thing im wondering if its the 3 mufflers on the exhaust system. one is like a cat which is right after the down tube of the turbo . then there is one below the passanger side of the cab about mid point of the cab then there is one after the rear tires before it bends outward, i cannot find a schematic on the exhaust system for a 159 inch wheelbase cutaway van with a 14 foot box . i dont think there are supposed to be 3 and when i punch it im getting back pressure and its kicking the wastgate back open but the vacuum is wanting to pull it closed

 

Hello,
ok i have an update. i have replaced my map sensor pdm and replaced the stock exhaust system with a 3 inch from the turbo down and then goes to a 4 inch with a flowthru muffler system and it still wants to buck and kick till the check engine comes on. i have tested the lift pump to make sure it stays running when it starts to buck and kick and it stays running wt 13.19 volts and draws around 5 amps up to 9 so that part is working. i ran the van without the doghouse to see if the wastegate moves when it kicks and it doesnt move at all but does move freely when the truck it turned off or i remove the line feeding it.. So at this point im at a loss no pun intended.

 

Put a lift pump in it anyway it could sound and act like its working but not do anything

 

Hello, ill give that a try even though its new doesnt meen its working properly and send the updates and thanks for all your help

 

i took my waste gate off and wired the flap shut and now get 11 psi of boost, but if i pull a long hill with too much boost it will go into fail safe and have to turn off ign for a few to reset ,in your case i would plumb in a vacuum guage into the pre lift pump line just to make sure a restriction is not causing this , i have also heard guys will pull out map and plug hole and check if prob changes , pcm wont see any boost then.

 

I was having the same with my 6.5 yukon and either when I went over 75 mph or just full throttle for around 10 sec it would drop off the power grid. it turns out the computer is defueling due to overboost and as soon as you shut the engine down and restart it should have full power. next time it falls on its face shift to neutral and shut down and restart and see if it gains power again.

 

Bucking and kicking sounds more like fuel starvation than defuel/limp mode.

Check the IP fuel inlet screens for debris as well as check fuel pressure at the IP when the problem occurs.

Not sure what fuel filter system your van has,but if it is like the filter manager in the trucks,the last ditch screen on the fuel heater mast could also be clogged.

The vent in the fuel cap may also be plugged,any excess vacuum when you remove the fuel cap?

A plugged sock on the sending unit is another possible cause?