So I have a 99 f350 with 7.3 liter turbo diesel . Bought it from an old timer during the summer only to find that first cold day below 30 degrees out it has an Un godly hissing sound until it reaches normal operating temp . Sometimes normal operating temp can take quite a while to get to in these low temps.Sounds like a huge vacuum leak in a gas engine. It only does it if I reach a level rpm such as in cruising. I can accelerate and it stops or let off the pedal and it stops. It sounds a lot like the hissing in the exhaust during warm up before touching the brakes for the first time.


I know Washington temps are nothing near as cold as The Dakotas and whatnot so forgive me if 20 degrees doesn't qualify as super cold with you

 

That's perfectly normal functioning of the exhaust back pressure valve (EBPV). It greatly restricts exhaust flow when cold to warm up the motor faster.

Mark

 

EBPS sytem is working as engineered to warm your engine up quicker.

 

thanks for the feedback gentlemen. Can I get rid of the ebpv or by pass it ? It drives me absolutely nutts. The strange thing is nobody else I know has this issue with their 7.3 . Im wondering if maybe my truck came from back east somewhere really cold

 

You sure can, and many do, but warmup might take a little longer. I use mine as an exhaust brake, which I find quite handy. Poke around at riffraffdiesel.com and you'll find the parts needed to delete it.

Mark

 

Thanks Mark!!!!!! Will do.

 

Oh, welcome to the 'hood!

Mark

 

X2 on the brake. It's the "snake brake"

Works great towing the mountains.

 

You can just unplug it for now if it drives you that crazy. Mine was unplugged when I bought it but I plugged it back in. It was 4 degrees this morning and even being plugged in all night it sure does help it warm up quicker. The sensor plugs in behind one of the top pulleys. If I remember correctly it's the passenger side plug. You'll see 2 of em there in front of the hpop. Just trace the wires. The ebpv sensor will go back and plug in under the turbo. I'm sure somebody has pictures on here that show it. Just search the forums for ebpv plug.

 

The correct plug to "unplug" is at the solenoid by the turbo.


Climb up on your core support. Looking back and to the lower left of your turbo pedestal you will find a lone connector that plugs in horizontally facing aft. There is a metal bail that you must flip up on the plug, after the bail, simply pull gingerly straight forward and viola.


This will disable the EBPV and eliminate your hiss.


It should not set any code and is otherwise harmless to the system unplugged. I take dieelectric grease and coat the plug as well as the terminal keep things clean in the event you want to use it or hook it up before a sale.


I'm in Northern Michigan and I will tell you as everyone else eluded........the function of this unit drastically warms the engine so cab heat is much faster and warm up time is greatly reduced.


I would urge you to bare with it. It is annoying but, it's a designed system that you will greatly miss. BTW, be prepared to let the truck warm up for a longer period. I wouldn't be to amped up about spinning it up and driving directly off. First time you do it will sound like a clown band.


Good luck friend.


Denny

 

While I really like the quick warm-up from the EBPV and the engine brake, I understand the distaste for the noise. There is another alternative. I installed a Diamond Eye Resonator (4" exhaust) with the baffles pointing upstream. [LINK]

It really tamed the snake hiss, but my turbo whistle out the pipe was just as muffled. Another perk - it subdued the 4" exhaust drone, which is what it's designed for in the first place. I haven't looked into a 3 1/2" unit for stock exhaust.

 

Rich, Did you replace your muffler with the resonator or add the resonator to the exhaust system? If it was added, where did it go? I've got the 4 inch drones as well and would like to quiet things down a little.

 

The instructions say to put it as far upstream as possible. I have mine under the passenger's feet and it knocked the exhaust drone/reverberation flat, but not the drone from my S&B intake. Still... the reverberation in the cab is gone, which is a huge help. I still have the aftermarket muffler, but the resonater made things so quiet that I may consider removing it.

There is one odd thing about the resonator, it hisses at the resonator when the EBPV is active, but it's not loud. It just made me suspect a leak when I first heard it.

 

I have always figured that the hissing had something to do with the heating of the engine. It is annoying but goes away relatively quickly. HOWEVER..........Last week it was high 30s to low 40s in Kentucky and it took almost 20 mins for mine to go away. I also experienced extreme power loss while it was hissing. I have never had the before. If I stopped to fuel up or whatever, even for a few minutes, it would do it again for about 5-10 minutes. None of this is/seems normal. I moved from Michigan where it is much colder and do not ever remember it being this bad. Especially the power loss. I would actually lose speed going up gradual inclines. Can this be stuck or do I have a different issue? I would prefer to keep it functional for the heat benefits but will unplug it if needed.

 

It can be stuck, I've had that happen. There was a flaw in the casting on my turbo outlet, and I had to file it down. You may also have an issue with a temperature sensor or the EBP sensor. Do you have a scan tool/gauge to take readings?