Powerloss/Hissing Problem

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Apr 19, 2015 | 12:28 PM

Northstar55

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Powerloss/Hissing Problem

Recently my 99 7.3 started losing power when accelerating after cold start-ups. I can put the pedal to the floor and it totally gags until it VERY slowly builds up enough RPMs and then the power comes back on. In certain lower RPM ranges I hear a noticeable hissing/whistling, almost like a high-pitch gear meshing sound which disappears when I step on it, but comes back when I let off the pedal. The powerloss seems to coincide with the hissing sound and when it disappears, the power is there again. I don't notice any white or black smoke when it's happening and starting is never a problem. After about 10 miles of driving when the engine is warmed up, the problem completely disappears and the hissing/powerloss is totally gone. Any advice is appreciated.

Apr 19, 2015 | 01:06 PM

hydro man 17

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From: Hat Creek Ca

That is most likely your EBPV (exhaust back pressure valve) doing it's thing. If this is a new development you may have a bas sensor or the tube from the sensor to the EBPV may be clogged

Apr 19, 2015 | 03:04 PM

Bonanza35

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From: Norco,CA

What he said. How cold is it there?

Apr 19, 2015 | 07:25 PM

Northstar55

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It's at 60F right now. When I started it up today there was a momentary hiss but it went right away and I didn't experience any power loss, so it just does it when it's cool/cold outside.

Apr 20, 2015 | 07:08 PM

oldboots1950

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From: Lampe, MO

EBP Tube

I had the same symptoms you are having. I took to tube out to clean only to find it had some holes in it. Replaced tube, cleaned soot out of the bracket and sensor and put it back together. Hissing sound was gone but sill lacked the power. I replaced the sensor today and the truck will throw everything on the floor and you back in your seat.
Pretty cheap fix. Be sure to clean out the hole in the manifold and the EBPS bracket as they are most likely plugged.

Apr 20, 2015 | 09:16 PM

Northstar55

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Thanks for the advice oldboots. I've ordered a new sensor and tube from Riffraff and will pay attention to cleaning out th bracket and manifold hole like you suggested. Hopefully that will resolve the issue for me as well.