I have recently moved from Alaska to Hawaii.
I brought my '98 Dak with me.
Yesterday I drove it to the top of Mona Kea, nearing 14,000' in altitude.

I was light headed.
The poor old Dak was also oxygen starved.
It was almost powerless over 12,000'.
It was all it could do to hold 25 mph and getting to 30 by using passing gear.
Granted the road is pretty steep.
It could pull those types grades better at lower altitudes.

I want to go skiing up there this winter.
I'll have to get myself an oxygen bottle, though.
Is there anything that can be done to tune the Dak for better operation at higher altitudes other than a turbo or an oxygen bottle for it too?

 

I would say to start be pulling the negative battery cable to reset the PCM and go from there.

 

agreed, this will let the PCM re-learn the significant climate change, and re-calibrate the fuel curves. That said, it will still struggle through the climate change from sea level to the top of the mountain, but right now, it thinks you are still in Alaska's sea level (low temp, low humidity, low water grains, low barometric pressure) when you are actually in hawaii (high temp, high humidity, high water grains, high barometric pressure). The IAT and MAP can only compensate so much given their previous calibration.

 

You don't have to disconnect the battery. From the FSM: In your case this also applies:

Still, 14,000 feet is a significant change. The formula for horsepower loss is:

(elevation x 0.03 x horsepower at sea level) / 1000

So, with 230 horsepower (new) you had only about 96 horsepower (at the engine) to move the truck.

 

Thanks guys,
From your advices, I see there are several ways to adjust the tuning.
But from 00DakDan's post, it should be resetting itself as it is driven up the mountain because of the way it has to be driven to get to the top, lots of floorboarding. Plus, turning it off and restarting it at the top. Although, that didn't help on the way up.

From the power loss formula, it only has about 42% of its sea level hp at altitude.
That might explain everything.

If the engine controls are not functioning as they should to compensate, then I should be getting a check engine light and codes generated, right?

 

If there is a fault then a code should be generated, yes. The PCM will adjust the mixture as needed.

In my opinion, you're just dealing with the altitude - as any normally aspirated engine would. I've driven around Colorado a few times. While it isn't as high an altitude, I do notice the loss of performance compared to driving at sea level.

Short of a turbo or supercharger you aren't going to get any more performance from your engine.

 

You could install nitrous plumbing and give it a shot when you're climbing at altitude.

 

That 3% thing really isn't very accurate, that is the average. At 14,000 ft you have an oxygen level of 9.8%. (9.8/20.2)x100= 48.5% oxygen available based on sea level. Reprogramming the PCM will help with keeping the fuel to air ratio correct, which could help keep your fuel economy decent. But you will no matter what will be running with a major power deficit.

An idea I've had is the cheapest (especially since you're in Hawaii) way to boost it would be get a used scuba tank and have it pressurized at a dive shop. Run it like nitrous but instead of a costly tank of nitrous it is $5-10 to fill an air tank, you'll get full engine power. While mostly this is theoretical it is a valid idea. I haven't done it, but something to look into.

 

actually, that wouldn't be a bad idea, like a 50 shot or less. I have a methanol injector inside a TB spacer for racing.

 

Not a bad idea, but even better would to set it up for O2 injection right at the throttle body--use compressed 100% oxygen instead of compressed air. Easy plumbing I would think, one could just run a bit of tubing to the top of the air cleaner, and have the o2 bottle on the seat in the truck. When you needed a little o2 boost, reach over and turn the valve on the tank.