Well. You learn many a thing on road trips, here are just a few:

1. Sometimes...ok your dad is pretty much always an @$$
2. My car (I think) doesn't like elevation
3. My car gets pretty good gas mileage no matter how hard I drive it

Here's the thing, my car ran GREAT in Wisconsin. I'm attending ASU now, so we had to get my car down to Arizona...enter the road trip. I got an oil change and complete service (I didn't have any time to do it, give me a break), and we left. Through Illinois and most of Missouri it ran like a champ. Around southern Missouri and early into Texas, it started to run a little funny. This got worse in New Mexico and progressed into Arizona. It ran terrible through the mountains (around 5000-7000 ft. of elevation) and I THINK got a little better as we entered Phoenix (around 2000 ft. of elevation), but it still runs wierd. I run a Jet Stage II chip which recommends premium but starting in Texas, the highest they had was 91 octane and I put in 90 once in New Mexico (Love's budget fuel, what a joke), so thinking this was the problem, I popped in some octane boost. Did it help? I don't quite know. The car idles fine and doesn't die. There is more of a "chug" to the exhaust now. The power isn't all there either (in the mountains I was getting passed by semis quite often but it's a little better now). I thought that the computer was retarding the timing because it was knocking due to the lower octane, but the check engine light never went on once. So now I'm pretty sure it's the elevation. I'm gonna' reset the computer first. If that doesn't work, I'll try the stock chip. If that works I'll bump up the timing and keep running premium to get back some power. If that doesn't work, is there any way I can use WinALDL to monitor and fix the problem? I don't currently have the VAFPR installed. If I bump down the stock fuel pressure could this correct it (by the way I'm assuming that I'm running way rich)? Any solutions would help, sorry about the novel

 

Hey, I go to ASU too.

I took a trip to Texas during the summer and found that my car became sluggish when I got there. I think the car just has to adapt to the climate (temp/humidity/elevation).

 

How long do you think this could take????? I want my power back

 

As you drove further south, you were hittting air which was lease dense (in the moutains) and the heat and humidity didn't help, either. If you are not running a fresh/forced-air duct and running with just the stock air cleaner or an open-element, heat was building up ever so slightly the more you drove.

I'm not an expert when it comes to the computers, but since you'll be at ASU for a while, disconnect the battery for 30 seconds or more. This will reset the computer and it will then have to learn your driving habits again. This time, it'll compensate for the higher elevation, temps and humidity.

Later,
Mike

 

But can the TBI injection system's computer compensate for elevation/air density changes? It's not a MAF system and I don't think that there's a MAP sensor (just an IAT right?).

 

The TBI computer will do it's best to compensate. Try nitroburn's suggestion and unplugg the battery for thirty second's. I have to do it everytime I mod the car in any way.

 

I had the same experience with my 98 S-10 when I went to school in AZ. I didn't go to ASU though. I was up in PRescott, where its 5000 ft. Elevation is definitely your enemy the air is less dense and there is less oxygen in the atmosphere (lack of oxygen=lack of performance). One of the best things I have found to help the car aclimate is to get an oil change as soon as you can when you get to AZ. Also ALWAYS run the 92 octane, no joking you'll notice an immediate drop in power if you change to 89 or 87.

The WI to St. Louis branch of your trek is the Ultimate fuel efficiency run . After that you hit the Ozarks (Up down up down the mountains) and then into Texas and on UP UP UP to Albuquerque.

 

TBI utilizes a MAP sensor, that's what compensates for elevation changes.

 

When the ecm first powers up when you trun the key on it looks to see what the Baro is (by using the MAP sensor).
As you go to Power Enrichment, the ecm also recalculates the Baro.

If you go for a long time, and change elevations, and never enter PE, or cycle the key on-off, the ecm has not refigured the new Baro.

Yes, at altitude you will lose power, and the gas is often reformulated for the higher elevations.