Alright my sig block or what ever should describe my(wifes) truck. She is the coolest and searches most all fixes and does all repairs while I drink beer and lend muscle when necessary. LOL! She is perfect!

So the issue, our fuel mileage is 10 mpg calculated. It sucks horribly and we can't figure out why. Why Power source(I think that's the name) as a cetane additive. What can we do to improve mileage.

When we get on the throttle to get on the freeway or pass someone we hear a loud bleed off sound on the drivers side of the truck. It is obviously on the drivers side and not confused with the turbo or wastegate. Those sounds are very distinct. What could it be. The intercooler boot right at the intercooler exit is very soft but connected well. All other boots attached to the intercooler system are really firm yet pliable.

We have replaced teh rubber bushing seals at the fuel return line tee, banjo bolts on fuel system, and installed a air dog 150 with 17 psi return valve pop off. We removed the entire stock fuel filtration system. Batteries, and starter are 1 month old. Can't think of anything else to add....help....I know guages! Next payday if I don't buy another locker for the Jeep...lol!

 

Loseing boost somewhere. Could be the soft part on the boot you found, but for sure loseing boost.

 

Like mentioned, it sounds like a turbo boost leak. Since there are two of you and you have an automatic, have it warmed up, then one of the two of you set the park brake and then put it in drive and powerbrake the engine while the other of you listens and feels for boost pressure leaking somewhere. Could be a cracked air to air cooler on one of the hoses connected to the syst.

BEWARE:

Don't run over the other person!!! LOL
Don't power brake it more than 15 to 20 seconds at a time, after 15 to 20 seconds you need to put it in neutral and run up the RPM to say 1,200 for a minute to keep from overheating the torque converter, then you can power brake it again!

 

We thought the same things and can't get it to recreate the noise up to 2800 rpm's power braking.....Lost now! Need a trust worthy mechanic in San Antonio, Texas.....

 

I'm assuming you dont have a boost gauge to see how much psi your losing. I can say that all the times I have worn into the boots or blown them off. they were major power robbers. did you check all parts of the intercooler tube from the turbo to the intercooler. also wondering if you have a leak on your intercooler.. anything weird looking in your air filter housing so this sound is it constant or only when you accelerate. you can make your own (home depot) pressure plug/ to check for leaks. if you have a air compressor and like 5-8 bucks have to find the link but many have done this. it plugs in the front of the turbo and has a valve/nipple to accept the air chuck. slowly put pressure through your system and you can hear the leak this way.
sorry for the bad wording on this DIY thing cant remember what they called those. have to search good luck and tell the wife its not going to fix it self get to the garage. LOL . later

Justin