Trucks runs fine until I put under loads, just small hills on highway. Rpms start pulsating let off gas and baby it up it's fine, changed tranny fluid and filter could a vaccum leak cause this or a sensor. No codes come up when I scan it so any help would be great. Thanks

 

I'm sure some of the other guys will jump in on this but I'm sure there are some questions they will ask first. More info on the truck (year, mileage, all that good stuff) would be good. Some of the sensors are year specific. You said you changed the fluid? What did it look/smell like? Any junk on the magnet?

 

Year? Engine? How many miles?

Have you done anything to engine or has previous owner done anything. First guess based on loss of power is possible clogged cat. To verify, remove upstream O2 sensor and crank up and drive it and see if it is any better. It will be noisy, but see if it has mnore power. If so, the cat is clogged and needs to be changed.

Now if the cat is clogged, you need to look at what caused it. I have a truck with 270,000 and still has original cat. they don't normally fail on their own. On these Rams, a common cause of failed cat is the plenum gasket on the bottom of intake manifold. To check this, remove throttle body and look inside intake. If you see excessive oil in the bottome, the gasket is blown and the cvacumm is sucking oil form crankcase into intake, through combustion chamber and out into the exhaust system. This excess unburned oil causes the cat to clog.

There is a sticky thread in the FAQ/DIY section on how to replace this. You can find a plate on ebay for arbout $50. If this is the case, you also need to replace the O2 sensor as well.

 

2001 dodge ram 2500 5.9 L auto with 112800 miles, truck runs great shifts good it's just when you put it under a load the rpms change like the torque converter is kicking in and out. The tranny fluid was old but didn't smell burnt nothing on the magnet either, motor is stock never uses oil or leaks any. Did some checking and some people describe there trucks done the same thing and it was the TP sensor.

 

Yeah, TPS is a great place to start, and easy to test. Use an analog meter.

 

Replaced TP sensor, plus found a vacuum leak on passenger side of intake repaired both. Took her for a ride and everything seems to be ok for now, would like to see after a longer trip but pretty sure it's fixed. Thanks for all the suggestions and input.

 

Good to hear you got it fixed!

 

Glad it is working. But just to be sure you get ahead of the game, checking the plenum gasket needs to be on your list. Hopefully you are good, and if you catch it early it will save you time and aggravation.

And with 3 girls, you need all the breaks you can get (I had all boys....girls probably would have driven me over the edge...) lol

 

Looks like you got a good result Dad-O-3! Kudos.

If you want more detailed information regarding the plenum gasket situation, then read the thread at the following link.

https://dodgeforum.com/forum/2nd-gen...um-thread.html

The texture of oil found in the intake varies and such, does not mean a leaking gasket is present in all cases.

 

Yeah it's on my list of things I need to check, and my kids push me over the edge everyday. Thanks guys.