New Engine Now I have VMSPC Problems

Had a Cummins factory reman ISB 5.9 engine installed in my 98 HR Endeavor. Tried to use the 4.* software version on a RCA Cambia tablet using Win 10. It was a no go. Lots of problems with it so I switched to ver3.* and it was better but had speed and rpm flashing as well as incorrect speed read outs verified by a GPS. Switched back to my old Sony laptop and ver 2.* software. Flashing stopped but the speed is off about 1 MPH at 30 and 5 MPH at 65. I think the RPM might be off a little compared to the dash analog gauge. Before the engine change every thing was spot on. Speed was very accurate. Any ideas on why it's acting this way. Could Cummins have change their software in the ECU? Everything else on the coach is the same. Transmission was not changed. I haven't driven it enough to see if their is any difference in the odometer readings but the temp and pressure gauges seem OK. Any hope of resolving this problem?

re: New engine

Is this a new engine ie. 2018 --or new-to-you and then, what year?

This engine may not have reliable j1708 data. If its a newer engine, post 2005ish, you may benefit from using its j1939 data instead. The v4.0.x software is still having parsing problems with j1708--as you found. Otherwise getting quite good with j1939. This as a way to understand why the software responded so differently.

So, as to why the speed is so far off; its an easy guess: mis-calibration. The engine hold the keys to syncing tire size, trans gearing and diff' ratio. The engine was used in a different rig (likely) and was set up for that combination. So, when the engine is sending its trigger pulse to the speedo, its timing will be proportionately off; hence your 1~5mpg error.

Your mission now is one of two options:
1. Hit the Allison shop to have the numbers punched in. The '100% solution"
2. Use the VMSpc to create a 'Multiplier' to compensate for the mismatch. "The 70% solution."

The drawback for option 1 is the $$ involved.
The drawback for option 2 is that is will be accurate in a single gear--say, 6th. Because the ratios are not (or likely not) the correct, the offset will only be accurate in the gear you've tested/driven it in. Typically, thats at-speed, freeway, over 40 or 50 miles, using your GPS as a reference.

The lower gears (and speeds) will be wrong (though by a negligible amount) by just using the option-2 multiplier.

Note: if you go with option 1, ask them to set it assuming 'new tires' --in the event your tires are worn down. This will improve accuracy.



New Engine

The engine is a Cummins factory reman. Unknown what it was in before. I assume the ECU would be updated with the latest software. The transmission was not changed. It was just bolted up to the new engine and reinstalled in the coach. I believe the rpm is off 30 to 40 RPM also. Is there anyway the VMSPC can read what the version of software the ECU is using? I had a new ECU installed on the old engine and the VMSPC worked just fine. I'll check with the shop that installed the engine to see what info they have.

re: reman Cummins

The VMSpc doesn't look for the ECU SW version. It could (and maybe should?) but at this point doesn't.

The shop will just need to program into the ECU the ratios, tire size etc and you'll be set. This is not a SW update--but needed elements which are programmed in by the shop after install.


Almost right now

I had a problem with the engine throwing a check engine light when cresting hills. Diagnostics showed a low oil pressure error a number of times. Shop found a bad sensor and also called Freightliner with the ECU number on the new engine to make sure it was setup for my coach. The shop set the latest settings in the ECU and now my speeds match (+/-1mph) between the VMSPC, GPS and the dash speedo. Everything is great except now the oil pressure on the VMPC reads 55 psi when the key is turned on and stays there all the time. The dash guage shows normal indications. It also a constant 55 psi on the data log. Any Ideas on this?

55 psi: A Cummins designed solution...

Do a quick search here on the Forum for "55 psi" *without quotes* for why. That should capture the nature of it.



Thanks for nothing Cummins....

So If I read it right Cummins just switched to using an idiot light approach for oil pressure instead of having guage so you can interpet if your having a problem. Now the engine can destroy itself before you get any indication their is a problem. I always thought that not having an oil temp guage was stupid but now taking away the oil pressure guage also is really srupid. Cummins is building to the lowest common denominator. Sell a $20k+ engine and won't spend few bucks to engineer a descent fix for a small problem. Guess I made the wrong choice spending $20k for a factory reman engine. Where's CAT when you really nee them...... sorry for the rant. I just thought that Cummins was a qualiy manufacturer. Maybe not......

re: Cummins

...Your mileage may vary...

Hello Wes,
Seems you never know what it'll be when you reach for a brass ring. It may be one that turns your finger green. ;-/

If we boil down the remaining issues with the new(ish) engine, its a speed correction issue of +/- 1mph--which is pretty good. Still, you can refine that more within the Engine Corrections table.

It is a heck of a deal that they still haven't figured out how to make the sensor work for variable pressure indication. Let me know when there's more we can do.