425 isl

Yes, you can add a chip to your ISL. I had a 400 ISL in my 2005 Diplomat. I added the Digi Cr chip that Parleys diesel used to sell. A couple of other RVers on another forum added the same chip. One RVer, had his dyno'd. It added 52 HP. It turned my Diplomat into a rocket. The chip did not affect the ECM. The chip was connected directly to the fuel rail. It changed the timing and fuel delivery. The good thing about the Digi Cr, it reverted back to stock settings under wide open throttle (WOT) so that you didn't exceed your Allison ratings.

When I sold my Diplomat, I removed the chip since the new owner (trade in) wouldn't know it was there or what to do with it. I figured my new 2014 with DEF couldn't use the chip, so I sold it to a friend with a 2006 ISL. By chance, I looked up the chip later on and found that it could be used from 05-present.

I acquired another one from someone selling their coach and intended to install it on my 2014, but they moved the plug to an inaccessible spot on the 2014, that I didn't want to try and unplug. Last week I was checking for other chips and found that Brazels is selling a similar chip called TS Performance. It attaches to the fuel rail like the Digi CR and affects fuel timing. The TS attaches at three different wires on the fuel rail.

Typically, Brazels has a booth at Quartzsite, so I'm going to get more info on their chip. I want to make sure it does the same thing as the Digi CR and reverts back to stock at WOT.

TS Performance

I ran the Digi CR for over three years and 27K miles. It also improved my mileage by .5 mpg.

Mike and Trish wrote:
Also make sure you have the most recent updates to your ECM. Any Cummins or Freightliner/Spartan/whoever built your chassis dealer can check and reprogram as needed.

Maybe yes, maybe NO.

I would ask what the "update" is/does.

There are four basic variables on engine specs: HP, MPG, longevity and for THEM (not necessarily you) EMISSIONS. These are balanced against each other-- unlikely you could reduce emissions and gain either HP or MPG.

So, I am not a fan of automatically allowing updates without knowing what it is meant to address.

Also make sure you have the most recent updates to your ECM. Any Cummins or Freightliner/Spartan/whoever built your chassis dealer can check and reprogram as needed.

In another post someone suggested that you contact the coach manufacture to determine if other components in the drive train can take the additional horse power. The transmission is one area of consideration, the other is the cooling system. More horse power means more heat, if the cooling system is not up to it you won't be able to use it.

BobGed wrote:
It depends. Call Cummins with your VIN.

Call Cummins with your ENGINE SERIAL NUMBER. They have no record of Vehicle Identification Numbers.

You probably have an Allison 3000...max HP is 450, hardly worth the expense.

NO you do NOT want to do that even if there is a chip for it. The ISL is already at the max torque for the 3000 Allison tranny...1200 ftlbs. If you look at the torque curve you will see they are already limiting the ISL's torque...flat at1200 ftlbs between 1100-1600 RPMs instead of a curve up to 1300+.

You need to learn to anticipate when you need more power...do not use the cruise except on fairly flat ground. Do not wait until you are part way up a hill before going to 100% power. At the bottom of a hill when I can see ahead in hilly terrain, I will be 5-8 mph above my normal cruise speed with the pedal to the metal. Also, do not haul around 800 lbs of water if you do not need it.

It depends. Call Cummins with your VIN.