When I drive up to the mountains, the max boost on my gauge keeps getting lower and lower until it hardly even moves. I understand how the decrease in atmospheric pressure affects cars, but shouldnt a boost gauge read boost, not the pressure going into the engine? Is this normal? If not, what could it be? Thanks.

 

oh yeah, i have a stock 87' TII

 

The intake is pulling in less air, so the turbo has less air to compress.. Turbo cars typically lose about 1% of their HP per every 1000ft in elevation. What's the elevation of the mountains there? When I lived in Colorado, I'd drive up to about *kft elevation, and my car still pulled fairly decently..

 

the mountain i usually go to is close to 6000 ft, and my second favorite is about 10000 ft. the car still pulls pretty good, but i have next to no boost on the boost gauge. I understand how boost equalizes with the decrease in atmostpheric pressure, i just didnt know whether or not it should be showing on the boost gauge.

 

so is it normal for my boost gauge to not read anything at high altitudes?

 

I've driven Mr. Grey (sig) to the trailhead of the Mt. Whitney trail (8,400 ft) and the effect on boost is dramatic from about 7,000 ft. on up, to the point where there seems no functional gain of hp at all. Also, it seems like the system just cuts out completely after trying for a while. I wonder if the Atmospheric Pressure Sensor or some other part of the emissions system was programmed to react at high altitude. Maybe NZ, Hailers, RETed, or one of the other Yodas knows.