Missing- poor milage

[bboone52]

My 7.3 developed a hissing sound when shifting into overdrive. I had never heard this before. after help with a performance specialist he has convinced me that the noise i am hearing is the turbo boost bleeding(?) back through the ait filter( I can hear it). he says this is common for the 7.3 to do this when there is excess boost. We both are baffeled that you can continue to hear the noise as the truck continues down the road. We are at present waiting for a ICM(?) and hopefully this will take care of the problem but I am not sure. when we take the ICM off the truck runs smooth and when we reconnect it it runs rough so we are hopeing this corrects the problem. the problem does not show up in the computor diagnostics. Any ideas?

[pipelayerjdh]

What model truck do you have. Yuo may have a stuck EBPV.

[bboone52]

2002 F350 - the computor showed the EBPV to have an error. I elected to remove the valve when we found it to be sticking. Removing the valve had no apparent effect on the truck except it takes a little longer to warm up. While the valve was being removed the turbo was checked and appears to be fine.

I have gone from 13 mpg to 10 when loaded with my Truck camper.

[blubyu90]

my seems to do the same thing. i have a diy intake on it. no codes and my mileage sucks. did you ever get this figured out?

[bboone52]

Not yet. i am waiting for it to break so I can figure it out. It is not improving. I just hooked up to a 20 foot boat and with my TC in the bed averaged 9 MPG from Miami to NC. I have averaged over 13 with the TC and a travel trailer behind it before. I am hopeing someone will see this and point me in the right direction but there does not seem to be much activity here. Do you recommend any other sites?

[MrJohnWayne]

Do you have a boost gauge. Could have a boost leak somewhere. The motor could be struggling to suck air in instead of having it forced in. Worth a shot to look at.

all your turbo bolts in place? The 7.3 turbos are known for the small 12 point bolts holding it together to come out and hiss. A good sign is if there is black soot around the turbo area.

[bboone52]

I have arrived in the NYC area and dropped the boat and the camper. After dropping the TC I reset the computor to performance (110 HP) and on the way home I notice the truck smokes now where it did not before. It never smoked unless I really gave it the gas and now it blows black smoke going up hills. It is starved for air I think. I do not see any soot around the turbo. How do I trouble shoot this problem?

[rankroddin250]

LOL your going to see black smoke on 110 hp setting my rolls the smoke on 80 hp when im lugging it down. i second the boost leak you may just have a loose clamp on one of your intercooler tubes... it probly will keep the boost in the tubes untill you realy pour on the juice and the high preasure in the system finds the easiest place to escape its def woth 5 mins to tighten all your IC conectors. you may also have a stuck waste gate which will drop all of your high end boost and will starve the motor of air