65 mph limiter removal?

[Patrick]

I've chosen a refurbed 98' C120 Freightliner as my chassis. In the specs it says the 65 mph limiter exists. Is the a computer reprogram issue or what?

[Gary Atsma]

You don't say which engine you have, but any dealer for that brand of engine should be able to straighten that out for you. I think Cat, Cummins, and Detroit all have the speed-limiter capability available, and should be able to be reprogrammed out or to whatever speed you want. I hope this helps.

[Patrick]

It has a N14 Cummins. I was hoping a reprogram wasn't necessary...sounds like it may be. Warpath, what did you do?

[onezman]

Patrick,

You can take your truck to any dealer service facility or any Cummins location. They can simply connect their computer to your ECM and reprogram the engine.

Have them remove all govenors so your speed is limited by your gear ratios only. Also, if your engine is currently set at 1,800 RPM, you may be able to increase that to 2,100.

Depending on the rating HP your N14 is currently set at, you may be able to uprate the HP and torque at the same time, (if your transmision is rated to handle the increase).

Total cost for this reprogramming should not exceed 1 hour labor.

There are many parameters that can be reprogrammed at the option of the owner. Check your engine manual for details.

onezman

[Warpath]

I will soon make my appointment with Cummins to have the limitor removed. I am having another issue which I am going to have them check as well. My motor shuts down after approx 10 minutes, while at idle. I think this is from low oil pressure and not a pre set timer, but I am not totally sure. I switch to synthetics and oil pressure improved to about 50 psi at start up, but then drops dramatically there after.

After that I need to get it to my Frieghtliner guy to replace the clutch linkage and re adjust the clutch.

Bill

2003 28' Show Hauler Motorhome on a 1995 FL 120 www.showhauler.com

[Doug]

I know that at one time, the Series 60 motors were set up to shut down after a certain period of time at idle, and the means by which the engine was able to confirm idle state was the oil pressure. I would not be surprised if your Cummins has a similar feature. The oil pressure at idle is lower than in any normal operating state. The way around this is to to use the cruise control to put the motor on a high idle if you need it to keep running. (As I recall, this was done simply by turning on the cruise while the parking brake was set.)

[onezman]

Hi Bill,

Doug is probably correct about the timer. Generally though, a timer is set at three to five minutes. You can, and should override this feature, by increasing the idle to 900-1000 RPM as Doug suggested.

Running at low idle is hard on these engines. Conversely, at high idle, the oil pressure should remain around 25-30 pounds. The engine will stay in it's operating temp range, and combustion will be sufficient to give you a good fuel burn. At low idle, the engine can cool down, then fuel will wash down the cylinders.

You will only burn about 1/2 gallon per hour at high idle. High idle won't hurt a thing.

For cold starts, I let em idle at low idle for about three minutes, then kick her up to high idle.

If you have normal oil pressure while driving, things are probably OK internally. How many miles are on your engine? When you have the limiter removed, have them download and print the complete history of your engine. This won't cost any extra.

If the history has not been previously cleared,
the ECM will tell you total hours on the engine, and mileage, which should agree pretty close to your odometer reading. The entire engine history is stored in the ECM down to the minute. If it's ever been overheated or over reved, the ECM will give you dates, times, how long. etc, etc, etc.

onezman

http://onezman.tripod.com/whitehotrvhauler

[OLDphoneman]

As others have posted -- take it into a Cummins shop and have the ECM reprogrammed -- from "Fleet" specs to an "Owner Operator" specs -- as there are many parameters that will change -- 2 of which are to defeat the speed govenor and anti - ideling feature.

There are a whole host of other spec's that will also change -- If you have the Road Relay computer -- also have this reset to "Owner Operator" -- as this opens up all values to be reset by the owner -- instead of a fleet shop with the proper cable and computer program.

OLDphoneman

[Gary Atsma]

OLDphoneman-
Good info on the truck computers. I was not aware of the "Owner-operator" spec. I thought each parameter was dealt with individually. Thanks from me, and I'm sure a bunch of others

[EduardB]

Hi I swapped out my transmission and differentials from another truck. The ratio on the original trany & diferentals was 3.9 I replaced with 2.93
It messed my speedometer by ~17mph i took it to local volvo dealer and the ajusted some parameter and now shows right mph!
For some reason thou, truck speed governs out at 64mph
Dealer raised speed governor to 85mph and it still governs out at 64mph
Patrick said something bout (speed being limited by gear ratio)
Anyone know what's going on?

[Mntom]

It sounds to me like the reprogram didn't work. Is there any chance of taking it back to the dealer for a retry?

[EduardB]

Oh yeah definitely taking it back, have them look back over...