As I recall, here in Denver atmospheric pressure is about 2.6 PSI less than at sea level. I am not sure how the ECM (computer) on the EVO copes with this, if it boosts pressure itself to remain at the stock 19 PSI @ peak, or if the ecm even controls boost levels at all....

There is also quite a bit less O2 up this high too, so I also wonder how that might affect changes in the fuel curve/spark advance table (on an ECM reprogram), and also how changing boost levels at this altitude come into play.

I do have some questions:

1. Does the ECM control boost levels? (to maintain the stock 19 PSI rating at any altitude) or is the boost level controlled mechanically?

2. To anybody at a high altitude, if no one knows the answer to #1: What does your boost gauge show?

3. Does anyone have experience with adjusting boost levels at this altitude? Could I get away with running more boost, because there is less O2, and less atmospheric pressure at this height?

4. Does the EVO use a OBDII ECM?


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1986 Iroc Camaro
305 TPI, Th700R4 Raptor Jr. tranny, w/thunderbolt servo, other upgrades. 3.23 stock rear