Is the Decel Tune Safe? - Ford Powerstroke Diesel Forum
User Tag List

LinkBack Thread Tools Display Modes
post #1 of 5 Old 02-14-2012, 06:38 PM Thread Starter Fanatic
WA_PSD's Avatar
Join Date: Feb 2009
Location: Washington
Posts: 107
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Thanks: 0
Thanked 0 Times in 0 Posts
Feedback Score: 0 reviews
Is the Decel Tune Safe?

I just got my DP tunes hooked up including "Decel" and was searching around the internet and found PHP doesn't offer it saying it can be unsafe under larger loads. Anyone with experience good or bad? Of course I see this right after I got it. Here's 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.

I guess i'll use this rarely, but under loaded conditions. Hope i'm GTG.

2002 F250 7.3 XLT EC LB 4X4
RideRight rear air/bags
18's 33" Toyo MT's
05-07 Grill, Tru-cool 4739
Add a leaf front
Airraid intake 4" Turbo back
DP-F5, NS,Stk,80E,Decel,80T

Last edited by WA_PSD; 02-14-2012 at 06:46 PM.
WA_PSD is offline  
Sponsored Links
post #2 of 5 Old 02-14-2012, 08:15 PM
Compression Ignition Addict
DrewGerhan's Avatar
Join Date: Oct 2010
Location: Athens and Cleveland, OH
Posts: 226
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Thanks: 2
Thanked 0 Times in 0 Posts
Feedback Score: 0 reviews
I saw that too when I was looking at PHPs site. Near as I can figure is that assuming your truck brakes are in at least decent shape and you have a decent set of trailer brakes on the trailer, why would you need an exhaust brake?

Semis, I can see. Up to 80,000lb is a lot harder on friction parts than our trucks can be.

E99 7.3L ECLB 4x4
140,000 miles
4" lift on 33s
6637 Filter
5" Diamond Eye
PHP Phoenix
Quad Gauge Pod
05-07 Headlights
DDM 55w 10,000K HIDs
800w Pioneer amp and 10" Kicker sub
Avital 5303 Remote Start and Alarm
DrewGerhan is online now  
post #3 of 5 Old 02-14-2012, 09:03 PM
Compression Ignition Addict
countryraised's Avatar
Join Date: Apr 2009
Location: northeast Iowa
Posts: 854
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Thanks: 0
Thanked 0 Times in 0 Posts
Feedback Score: 0 reviews
Or you can buy upgraded valve springs and run it all the time.......

John Deere product developement
FOR SALE '99F350 2008 F350 mini maxx'd

countryraised is offline  
post #4 of 5 Old 02-14-2012, 11:53 PM
Serving Our Country!
JSchuricht's Avatar
Join Date: Aug 2007
Location: Manor, TX
Posts: 2,962
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Thanks: 0
Thanked 23 Times in 22 Posts
Feedback Score: 2 reviews
The weakest link is probably your transmission if you have a auto. I run a manual TC lockup and manual EBP exhaust brake which is basically the same thing as a decel tune. I couldn't immagine running without it when towing, it really saves the brakes.

JSchuricht is offline  
post #5 of 5 Old 02-15-2012, 02:50 PM
Compression Ignition Addict
dieselcrawler's Avatar
Join Date: Aug 2007
Location: New Martinsville, West Virginia
Posts: 3,158
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 4 Post(s)
Thanks: 0
Thanked 46 Times in 44 Posts
Feedback Score: 0 reviews
I've been using my decel tune on my DP for over 4 years... the trans was rebuilt at 150K miles, tork converter went out at 175K, was replaced, and now at 220k, it's starting to act up again... but concidering how I use the truck, towing, hauling, driving it hard, I doubt the decel tune is the sole culpret in the trans issues I'm having... the 4R100 is the weak link no matter how you look at it, decel tune or not... and the fact that the rebuild only cost $1500 when it was done in 2007, I'm not complaining. I'll gladly have the same guy rebuild it again in the near future, and continue to use my decel tune.


'99 E350 DRW Stahl 11' util box van, 7.3 PSD, stock. 138k SOLD

'00 F350 extcab, 9' utility bed, dually 221k

E'99 F250 extcab, S/Bed 211k

'00 Excursion Limited, 7.3PSD 281k

'84 Chevy K-30, 6.2L TD, woods/trail beater. 141k

Semper Paratus
dieselcrawler is online now  
Sponsored Links

Quick Reply

Register Now

In order to be able to post messages on the Ford Powerstroke Diesel Forum forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Please enter a password for your user account. Note that passwords are case-sensitive.


Confirm Password:
Email Address
Please enter a valid email address for yourself.

Email Address:


Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.

Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page
Display Modes
Linear Mode Linear Mode

Posting Rules  
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On

For the best viewing experience please update your browser to Google Chrome