Just wanted to let everyone know who has the IXS Cummins series engines some tips. Most people who have alot of experence know these things but there might be some people here they might find this very helpful.

Most engines develope most of their power at 1650+ RPM. CATs love high RPM and hold very high torque at this level. Also causes high head pressure ( Cats usally run in the 55 to 65 range in oil pressures. )
This holds same with Detroits (50-60 PSI).

The ISX cummins are build a bit different they run very very low head pressure (30-35 PSI) and develope the most power at 1250 RPM.
The advantage to this is better fuel mileage while in a hard pull in high gears.

Examples: CATs love 18 speeds so while climbing a hill with a heavy load can keep their RPMs up therefore loosing little speed but at a cost of more fuel.

Cummins will bog down to 1400 to 1200 RPMs in a 10 speed and hold the same power and torque while also saving fuel.


Hope this helps some people out who have the ISX cummins engines.

Not over here,I work with a lot of 600hp ISX engines and they are all driven hard up around 1800-2000rpm all day.When my C16 was stock it never went over 1600rpm on a hill same as a C15 CATs are a low reving engine look at the ACERT they love it at 1200rpm.

Well yeah 600 HP ISX will pull anything just about. Talking more about us company drivers. The ISX 400s and so on with heavy loads.


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ISX 600s still pull their max torque at 1200 RPM.

ROFLMAO


CATs do not like high RPMs. They build their torque at 1200 RPM, peak HP is usually around 2100.

I never had to drive any of my CATs above 1500 to 1700 rpm to get plenty of power and MPGs out of them.

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The only thing I didn't like about the older CATs was they fell too quickly off the power-band so you couldn't mess around on the shift. It was "shift or get off the pot" The old Detroits I drove were like my old Yamaha DT 250, you had to damn near run them out redlined to shift.
I haven't driven the new CATs yet so I don't know if that's changed.

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The trouble with the world is not that people know too little, but that they know so many things that ain't so
- Mark Twain

Let's support our new president,
but Obama should remember one thing,
Gray Davis.....

Ron the 3406E and C-15 and 16 all love to pull below 1500 RPM. Or thats been my experience.

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What I wish is that someone would actually know how to fix problems in an ISX, I have had trouble with one nearly all year, with it missing when the fuel gets hot, and those darn things return the fuel very hot to the tank. It's been to a shop,for this problem twice and it hasn't been fixed, they can't figure it out, they thought last it had bad o-rings in the head that the injector fits into. It still isn't fixed, now I'm running a Detroit 14 with a sticky EGR, the check engine light is on but it runs.

The ISX won't run decent more than about 40 minutes then it starts sputtering and missing, it will stall at idle(800rpm), with still no code to read.

The company is in a bind,not spending the money to do anything right, but I do like the job I have, meanwhile, I can't find out anything about the darned ISX, the ECM trips but won't show a code, sometimes even when hooked to a computer. Of the 4 they have there is now 1 left running.
There is no coolant anywhere it shouldn't be , no fuel where it shouldn't be and no oil where it shouldn't be. The darned thing should be repairable, but isn't.

It does pull really well when at low revvs, better than anything else I have driven, which is a good thing considering the first 4 months I drove it, it didn't have 9th gear, or 4th for that matter. I really must like this job. Now it has a remanufactured transmission that took 2 months to break in but the motor won't run right. BTW we are legal to 86 K in Iowa, and it's often loaded up to that point. I drove it and got there and back, heavy or not

Is there anyone that has enough experience to solve this mechanical mystery? I'm thinking its' something simple, that is being overlooked.

I was actually talking about the 3028's, a real dog no better than the Ford 270's they used to put into the company dumps I ran.

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The trouble with the world is not that people know too little, but that they know so many things that ain't so
- Mark Twain

Let's support our new president,
but Obama should remember one thing,
Gray Davis.....

I think you're getting confused by some of the programming in the ECMs and missing some of the important aspects of these engines.

C15/16s and ISXs fundamentally do not run all that much different. However, their ECMs and programming are EXTREMELY DIFFERENT.

When running an ISX you should of course stay at low RPMs and shift early. The same is true of CAT.

Of course a lot of drivers will run a CAT up because the ECM has soft limits, so you get max torque to the soft RPM limit where it starts to cut back torque output until you hit the max RPM limit. This allows you to shift easier on uphills of course. Cummins on the other hand uses a different method and it penalizes you heavily after exceeding the soft limit and will rarely let you hit max RPM when under load.

This (as well as the fact that CAT is speed controlled and cummins is torque controlled) is why you often hear drivers that started on ISXs call CATs gutless and of course why CAT drivers call ISXs gutless.

You really have to look at the programing and the options you select at the time of order or the options the fleet or previous owner set up.

I worked on a few of the newer engines , service the fuel system ,check your injector activation pressures, and do a cut test to see if they past. Start from there, hope this helps.