# 95 7.3 power robbing hissing



## sparksrides (Dec 1, 2008)

i have a 1995 f 250 with the 7.3 psd, when i start the truck i get this hissing sound that seam's like it's coming from the exhaust like a by pass or some thing. it usually only last about 5 seconds and only does it on first start when the motor is cold weather it is cold out side or not, and if i shut the truck off and the motor is still cold it will do it again when i restart the truck. when it is real cold and i don't plug the truck in it will last a lot longer, i have to warm the truck and shut it down and restart to get it to stop. when driving with the hissing it robs all the truck's power. when i plug the truck in (any time below 40 degrees) it is the usual 5 second's . i seen another truck do the same but it did it the hole time it idled on cold days and only stopped when i revved the motor. it is driving me crazy and my mechanic doesn't seem to think it that big of a problem, i don't think he knows what the problem is or how to fix it ether that or he is lazy. any help would be greatly appreciated ps sorry about the long post just trying to explain the problem :realmad:


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## exmark1 (Nov 30, 2005)

Im not sure what it is either... but my 1995 psd F-350 does the EXACT same thing! It's annoying but not an issue is what I was told as well.
If you find a fix for it let me know!


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## ford550 (Nov 9, 2008)

I had the same thing happening last year on my '99 7.3L F550, drove me nuts. Sounded like an exhaust leak. Was worse sounding when you passed things that made the sound rebound to you. Anyway, I told the dealership what was happening and they said nothing was wrong. You would figure for $95/hr they would be able to figure it out. So I had one of my guys throttle the engine, while I was up front on top and underneath the engine. Well low and behold within 5 minutes, there it was. Looking at the motor from the front on the left side, there is a 1/4" dia tube running from the front of the header (manifold) up to the front of the motor to a sensor. This tube had rusted out and litteraly broke in half. So everytime you hit the gas air was escaping from the header out of this tube making the hissing sound and robbing power. So, went to ford, bought a new one and it fixed that hissing sound. Unfortunately I don't remember what it was called. Hope this helps.

Chris


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## oldmankent (Mar 2, 2001)

that is the exhaust backpressure valve. EBPV. Causes the motor to heat up quicker when it is cold.


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## MAR4CARS (Oct 6, 2005)

I have a 2000 f350 coming into the shop next week for that same complaint ...


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## Dstosh (Dec 30, 2003)

Guys. No big deal. You can unplug it, It is right infront of the turbo on the driver's side. It is a two wire plug. Unplug it and zip tie it up. Takes two seconds.

http://www.plowsite.com/showthread.php?t=69689

Link to another thread about the same issue.


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## sparksrides (Dec 1, 2008)

thanks a lot you guys nailed it, this site is great very helpful info


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## brad96z28 (Aug 21, 2005)

Yep common and easy to fix.


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## Doakster (Aug 15, 2008)

Sparksrides.....if you want your truck to warm up properly as designed keep the EBVP plugged in, that's what it's there for. 

If you just can't stand the noise then unplug it, but for the majority of us that live in cold climates it is something the 7.3 should have functional.


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## sparksrides (Dec 1, 2008)

i just unplugged it and no more hissing. most of the time it only last five seconds but some times it seems like it sticks and drives me crazy when i am driving. another time when plowing it started out of no where hour's after start up. i plug my truck in as much as i can so warm up is not a issue. will leaving it unplugged effect me in any other way?


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## Dstosh (Dec 30, 2003)

No, It will just take a bit longer to warm up. I have been running both my trucks with out it for over a year. I havent even seen any bad effects.


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## Doakster (Aug 15, 2008)

Dstosh;664696 said:


> No, It will just take a bit longer to warm up. I have been running both my trucks with out it for over a year. I havent even seen any bad effects.


I would agree with that. I just like my truck to not take forever to warm up, my high idle on my chip helps as well.


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## sparksrides (Dec 1, 2008)

when i plug my truck in it is warm to start the heat is warm and the truck starts right up. i have another question a little off topic but i am adding a trans temp gage and was wondering if i can get away with out welding a bong into the trans pan. can't i just sandwich the sensor between to rubber gaskets much like the after market drain bolt they sell


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## oldmankent (Mar 2, 2001)

You can also set up the EBPV as an exhaust brake. I have it setup in my truck on a switch so that it either runs stock with the EBPV doing what the ECM tells it to, or turn it off completely, or switch it to exhaust brake which runs through a foot switch next to the clutch. Can turn it off or on whenever.


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## sparksrides (Dec 1, 2008)

that exhaust brake thing sounds cool, can you give me details on how you wired it up


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