today I drove from my house in Cameron Park CA (1200 ft elevation) to Mt Rose, Nevada (8200 ft elevation) to do some skiing, and on the way up there, the check engine light came on, and it became more gutless than before, and it used a lot more fuel. I know it doesnt have an oxygen sensor, but the light didnt come on when I disconnected it and it ran the same (leading me to believe that it wasnt working in the first place). But here is the strange part: most of the time on these things (89-90 models) The engine check light flashes code (for instance, 1 flash followed by 2 shorter ones means 12). but this time, the check engine light stays on continuously, and the chiltons manual says that when the light stays on, it means ECM failure. The thing that puzzles me is that the engine still runs, and when I got back down to the elevation of my home, it ran the same as it always has. I normally wouldnt care about the check engine light being on, but it has to pass smog within a few months, and the cost of a new or reman. computer, plus the cost of an exhaust system make the car too expensive to smog.

What is your mileage?  This light comes on at 60,000 and 100,000 to remind you to check the emissions system.  To shut this light off, flip the little switch under the dash to the right of the steering column.

You may have an ECU failure, the ECU has back up circuits that take over in the event of a processor failure so it will still run. It could take a while to notice that the O2 sensor isn't there. I would expect a CEL if its not present, Wild would probably know for sure, he has an 89. O2 sensors aren't that expensive, I would put a new one in and then take it from there.

I had a similar problem with mine.The check engine light came on and i could not get it to go into diagnostic mode(flash codes) i swapped in the computer from my parts vehicle and then it ran fine and would go into diagnostic mode.

Thanks for the advice. Today I was driving it and it started running on 3 cylinders when I was sitting at a stop light . I get to my house and look at the exhaust pipe while revving it, and it was making black smoke, so it was a ignition related problem. Then I inspected the spark plug wires, and they seemed fine, and when I restarted it, it ran fine, but the check engine light is still on. It would make sense that it would run with a bad ECM if there is a backup circuit. The strange thing is that even with a bad ECM, it still seems to have plenty of power most of the time(usually when I go down in elevation). I wonder where I can get a ECM for a reasonable price. If I get one from the pick and pull, it will probably be cheapest, but it can also have the same problem as the one I have, plus I own a 1990 trackick, and I know it is the same as the 89 with the vacuum advanced ignition system and one wire O2 sensor, but I dont know if a 91 on computer is compatible, because 1991-on trackicks were OBD1 models with the 3 wire O2 sensor and the electronic advance ignition.

If you have a radio repair shop near by ask them to check the capacitors. It sounds as if you have no altitude correction, which you won't get on the back up circuitry. It could be that the 5V power to the external sensors is gone.

I reset the check engine light by disconnecting the battery for 30 seconds, and it has yet to come back on, but I also havent driven up to anywhere above 5000 feet, so I will have to wait and see if the light comes back on. It seems to drive just fine while I am around the elevation that I live (1200 ft), and it gets more power when I drive down in elevation, but it really loses power once I  go past 5000 ft. I wonder if the 91 to 94 8v trackicks computers are compatible with the 89-90 trackicks. If they are, I will grab a computer out of one when I see one in pick and pull, although the ones in the junkyard can have the same problem with the capacitors. When I looked at the one in mine, it looks like it has been replaced before I owned it, so it might have had this happen once before.

Well the ECU only takes an altitude reading when you first turn on the engine. So if you drive non-stop from 1200ft to 8200ft then the ECU won't correct for it. I have no idea what kind of distance you are talking about or the terrain but if you turn off the ignition at high altitude and then turn it back on you should see an improvement. I'm rather curious about this as I haven't been able to find any definitive numbers for altitude correction. I've left it out of my ECU design for now as they're aren't any mountains anywhere near me.

the distance I drove was about 120 or so miles one way. I stopped a few time to get food, so I stopped and restarted the motor a few times at 5000 to 6000 ft. It didn't turn on until I was driving about 45 mph on a straight road that was slightly uphill. It got real gutless when I got to about 7000 ft. At the ski resort (8200ft), I stopped and restarted it(because I went skiing) and it was just as gutless as before, so the altitude adjustment must not work. What I should do is drive up to the mountains or down to the valley and check the sparkplugs to see if it runs richer or leaner at different elevations.