I have a 19999 Dodge Ram 3500 Dually 5.9l Diesel. The engine is stock no mods, all factory original intake and exhaust with an exhaust brake.

First my cruise control stopped working and now while trying to hold a constant speed I get intermittant surging, the engine will drop in rpm's and and then surge back above where it was before and then return to the speed I was holding it at. Originally only did this at lower speeds, now is becoming more frequent at higher speeds.

Any ideas? I am new to Diesel's so I am lost... EGR Valve? Throttle position sensor bad? Fuel filter clogged?

Any help would be appreciated.

 

the lift pumps are horrible on those motors and they really dont like dirty fuel filters so make sure you have fresh filters.id need more info though to help you.as far as tps the throttle pedal is the tps and they are not on the cheap when they go you loose the pedal all together .surging could also be caused by a weak wastegate on the turbo or 1 that is slightly stuck open .trouble shooting your 5.9 isb can be a drawn out process.and a costly 1.any codes engine lights so on.the cruise problem is probably a broken wire to or from the ecu .let me know if you pull any codes from it i can tell you what the cummins factory codes mean and what to look for .the dodge side of it not so much.

 

I will move this to the diesel section, get you more help that way. Mostly gassers over here.

 

Sound like the APPS(Accelerator Position Sensor) is going out. Google 'Timbo APPS' for information on them. Also, Do you have any gauges on the truck. If not you need at least a fuel pressure gauge, EGT, boost and if an auto trans. a trans temp gauge. This way you will know what is happening to you truck. With the surging, the APPS could be failing, The lift pump may be out, the injection pump could be out, there are many things that cause our trucks to surge.

How many miles are on the truck?
Have you had the truck scanned and are there any codes present?
When was the last time the fuel filter was changed?
Is everything topped(fluids) of according to the manufacturer?

These are a start, others will chime in.

 

sounds alot like torque converter locking-unlocking, the cause of it 99% of the time is bad ground connections, remove them all battery/body all of them, clean them, and reinstall

 

I just changed one of the batteries not long ago before this started happening.... hmmm will check all grounds.

The truck has 116k on it, fuel filter was changed about 3 oil changes ago... all other fluids are in good shape and up to mfg specs.

I have no other gauges in the truck, although I am looking into installing them.

I did speak with a friend who is a mechanic and he says there are a couple of service bulletins describing what I have and all it says to do is have the computer re-flashed.

I think I am going to make sure I check everything else before giving the dealer any of my money for re-flashing the computer.....

thanks for the help!

 

That may be some of your problem as well. ALWAYS replace both batteries at the same time.

 

How do you re-flash the computer?