My Dodge Ram 1500 runs alright at about 0 feet, spinning tires in the dirt and gets up and goes nicely, but at 4000+ feet it turns into a pig. I was up in the trails on Saturday (around 4000 feet) and even in 4 low I couldn’t get up certain obstacles that at 0 feet wouldn’t be a problem. I notice that around 3500 RPMs the engine seems to choke, not wanting to hit that 4000 RPM range. It stutters, has what seems half the power. I’m thinking that the ignition isn’t hot enough or the air is too thin. I was thinking about putting a MSD ignition in but if the problem is elsewhere than I would rather not spend the money.
I have a 5.9l, 6 inch lift and I believe 33s possibly 35s. Oh and of course the original gearing. Now I know the gearing is a problem but not with the altitude I’m at.
Any suggestions???

 

Welcome to DF
Elevation greatly affects performance, especially with the wrong gears. What are the numbers that are on the side of the tires?

Check to see if the computer has a sticker on it with a date of reflash (dreaded deathflash) and also if your plenum gasket under the kegger intake is leaking. Those 2 things will really kill power and make your truck useless at altitude. Cat going bad also hurts performance when it plugs up.

If those are 35s you really need 456gears to make it halfway decent performance wise. 4.56 gives 3.96 final w/35s. Otherwise you are trying to make up for wrong ratio, much heavier tires as well as the altitude breathing issue. 3.55grs w/35" tires gives you a horrible 3.08 final gear ratio

 

My truck tends to run slightly rich at high altitude because of the thinner air, which in turns robs power. It will compensate over time if i'm there long enough, but sometimes I use an a/f controller to adjust it if I need the extra power quicker. I live at about 7000ft, and I can tell a noticable drop in power when I get up over 10,000 or 11,000 ft.