Closed EBPV?
Cargo Master
Joined: Jan 2001
Posts: 2,726
Likes: 5
From: Slatington, PA
Some people wire it up as an exhaust brake or so they can manually activate it at idle to warm up the truck faster (when the PCM doesn't automatically do it). Those are the only two uses I know.
Posting Guru
Joined: Jan 2007
Posts: 2,364
Likes: 3
From: Gilbert Az.
Trey there are no cons to "closing off the valve" as it is only used to rapidly warm up the engine in freezing weather it can be set up as an exhaust brake with just a relay and some clever wiring (search function) that's really very effective! And nearly free!
Laughing Gas
Joined: Mar 2004
Posts: 789
Likes: 16
From: West Coast/L.A. Area
One of DP's "tunes" closes the valve and uses it as an exhaust brake. I have it and it works great. Driving in the Sierras and pulling a 15K trailer was at times terrifying. I used to go down to 2nd (auto trans) and brake, brake, brake. Now 2nd with the DP tune is to slow for me. I go down the Lee Vining and Sherwin grade in third and it won't go much over 60 and i never use the brakes!
Postmaster
Joined: Dec 2008
Posts: 3,340
Likes: 2
Php does not offer a decel tune. I guess they feel it can cause some issues. Here is a quote from their website
" Do you offer a "decel" or "exhaust brake" calibration? Simply put, no, we don't because it goes against our business philosophy which, in part, is to provide safe, reliable products to our customers.
For those who don't know, this is a calibration that uses the EBV (Exhaust Backpressure Valve) as a makeshift exhaust brake. While this setup may work reasonably well for lightly loaded vehicles, we generally do not recommend this type of calibration... at least not for automatic transmission vehicles. There are a few reasons we don't recommend this.
First, in order to transfer the energy of the moving vehicle to the engine during deceleration, two things must occur: the torque converter must remain locked, and the coast clutch must be engaged. The problem with this is that the coast clutch on a stock transmission only has 3 friction plates, and these are smaller than the standard forward clutches. On 2001 and later transmissions, you also run the possibility of damaging the intermediate sprag or "diode," which will result in an immediate transmission teardown. Again, lightly loaded vehicles would have less of a problem with this, but the general idea of an exhaust brake is to be able to slow larger loads without overheating the standard brake system. It is these types of loads that can cause transmission damage. Obviously, a manual transmission would be free from these types of situations.
Second, whenever you increase exhaust backpressure, you need to make sure that the exhaust valve springs are capable of preventing the pressure in the exhaust system from lifting the exhaust valve from the valve seat, as this would result in a collision with the piston. Normal valve spring seat pressure is 70-75 PSI for NEW valve springs and deteriorates from there. Given that the surface area of the back of the exhaust valve is approximately 1.9 square inches, it would take only 40 PSI of exhaust pressure to lift the valve off the seat, even with new valve springs.
To put it simply, if you plan to use an exhaust brake, either through the use of the EBV or by purchasing an aftermarket stand alone unit, you will need to consider the condition of your transmission and exhaust valve springs in order to ensure safe, reliable operation."
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