Hi Scotty, I have a 2012 Chevy Silverado LS 4.8L V-8 2 WD Auto Trans 115.293 mi. On traveling thru Colorado 2 years ago, on the west side of Vail, I could not get any faster then 60 Mi per hr, and that was pushing it. (milage was in the 90's at that time) When I got back to St. Louis, I took it to the dealer for a look see, and there was no problem. The dealer told me that the engine was too small for that size truck. What's your opinion? Purchased this truck new in 2012. Thanks
Well sometimes vehicles will not run right at high altitudes and when you get back to normal to do just a run okay just stay away from high altitudes
The problem is that at high altitude, your air fuel mixture becomes very rich because there is less oxygen per liter of air. The computer system in your vehicle should have automatically corrected for that situation through the 02 sensors. If I were you, I would get a deep scan on the ECM to see what's going on.
There is an electronic barometric cell built into the ECM to compensate for altitude. Thanks, Sigmund, er Figmund.
Nope. Mixture does not get rich. The MAF sensor will measure less air coming in, and the PCM will trim the fuel amount down to maintain the ideal Air-to-fuel ratio of 14.7:1.
However, the engine receives less air AND fuel, so power is reduced. Colorado Springs is at around 2,000m elevation, where air density is approx 20% less.