2nd gen cummins having some issues

[2ndgendog]

Hey guys! I have been lurking for a while and figured I would join up to see if you had any insight to a problem I am having. I have a 2001 2500 ram with a Cummins and a 47re, it has an S&B intake, a 4" mbrp exhaust and a fass 100 lp. Other then these things the truck is completely stock with 230,000kms (143,000 miles) never been tuned. I do not have gauges yet and I know that fuel pressure is the first thing you`re going to tell me to check, gauges are on the way hopefully be here in the next week or two (thanks covid). The issues I am having are low power while climbing hills on the highway (unloaded I do not pull anything with the truck), here in eastern Canada we have a lot of steep long hills but the truck should be able to hold 120km/h (75mph) going up them no problem! I took it into the dealer to have the ecm reflashed a few weeks ago hoping that the torque management system was still active but the reflash did not fix my issue. I am finding the truck is having lower power around the city now, it seems to rev high and is sluggish to get up to speed but if you really put the throttle around town it takes off pretty well. I also have noticed that when it is under load, truck empty along with the low power I will see my coolant temp begin to creep up from where it usually runs, it never overheats but when the truck is revving I definitely see an increase in coolant temp on the gauge (though it is slight). When I am on the highway on flat ground the truck will work great holding 120km/h(75mph) but as i come uphill ! can floor it and it will not maintain speed, it does not smoke at all under normal conditions, if I really hammer it from a dead stop I can get a tiny puff of black smoke but that is just the way these trucks are with factory tune. The fass is not even a year old, but I can`t be sure it has good fuel pressure until I have gauges so I have not been driving the truck because I would rather not destroy a vp44. Any insight you guys have would be appreciated, I am a red seal auto tech here in Canada but have been out of the trade for a while and I know that you guys all love these trucks and there is a lot of cumulative experience in these forums. 

[dripley]

You sure the tranny is not slipping? If it is reving higher and not accelerating up hill its sounds like tranny may be low fluid or need a fluid and filter change. A hill with a stock truck empry should not be any problem for the truck.

And welcome to the forum.

[2ndgendog]

thank you for your reply!! But I am 100% sure the trans is not slipping. Shifts firm no flares, part of me just wants to throw a tuner on it and see if that doesn`t fix the issues. And do anyone who reads this knows, there are no current codes checked with the key trick and a snap-on modis.