OK, 1996 Ram 2500 4x2 V-10 with 170k.
Main problem is no horsepower when you stomp it or tow, it runs fine in town, but when it time for that V-10 to go to work it wont.
When you really push down it acts like a missfire and sometimes will backfire.
Here is what has been done so far and I'm still without a clue.
1. plugs and plug wires changed and yes #5 & #7 arent crossed
2. Cat was removed while going cross country on the side of the road and now I'm running straight pipe with a muffler(muffler clog?)
3. OBDII detects no codes and check engine light is not on
4. Fuel pressure on the rail is at 40psi constant (accel or idle)
5. Have run Seafoam through gas tank.
6. Engine temp runs around 180 except when towing in extreme heat, then truck runs around 200
7. Air Filter changed and no oil in plenum......
8. Did find a mouse nest under the throttle body but "saw" no chewed wires
9. Transmission checked at local shop on a trans scanner on the road and all is good
10. Regular oil changes with 5W-30 every 25-30k
11. Startup in ok but idles rough for a few until warm.

Now is where the fun begins, coolant temp sensor, cam sensor, crank sensor, EGR,..........pull the injectors and check resistance?........pull the fuel pump?.....
I have seen on other forums where most have no clue where to turn and I dam sure aint goin to the stealership to do this and that until it may get fixed.......

So there is the challange...anyone have a clue.......

 

@170K miles I'd probably start with a compression test, and early v-10s are prone to crkacks in the Cylinder heads, do a leak-down test.

 

Maybe a 02 Sensor...?

 

Just because fuel pressure is ok doesn't mean fuel volume is ok. Maybe you need to ck fuel volume. I used to know the basic spec for that, but I just cant remember it now.

 

Problem solved.......................FINALLY!!!!!!!!!!!!

Found that when I disconnected the vacuum line at the intake plenum the RPM's went through the roof.......also found that the line had a pretty good amount of crud in it.........sprayed the line out with carb cleaner and reconnected.......dam thing runs like a brand new truck!!!!!!!

To all those out there experiencing lack of horsepower.......by all means, CHECK YOUR VACUUM LINES!!!!!!!

 

Good advice

 

my truck was running like crap no power etc like you mentioned i was at a loss then i found a bad vacuum line at the evap cannister repalced and what a difference. i finally have my truck running really good with just a few minor things that ill work out eventually. but you sure are right a vacuum line will crush your performance

 

did the truck pop out the exhause or run during all the power ranges?

 

am i reading that right...oil change every 25000 to 30000?