Uprev fuel tables with elevation

RadioFlyer

A good way to think of it is:

Open loop fueling is when the car just runs whatever values you have in the fuel and timing tables. Or, it tries to hit those AFR targets and makes corrections based on the knock detection. This is the mode you're in when you're trying to accelerate more than, say, 50% throttle pedal input.

Closed loop fueling is when the car tries to maintain 14.7 in cruising and light throttle applications. This is your daily driving mode where you're cruising in traffic. Barely touching the gas pedal.

One way to see which mode you're in at the time is to log, or monitor with Cipher, the fuel trims. It doesn't apply the fuel trims (that you can monitor in Cipher) in open loop. When you drive in closed loop, the fuel rims are constantly adjusting. So you'll see the fuel trims go from 108%, 95%, 110%, etc. while you're really light on the throttle just maintaining a cruising rpm. Your AFR's will be reading pretty close to 14.7. But when you tip in on the throttle, and the AFR's drop, you'll see the fuel correction go to exactly 100% and stay there as you sweep through the rpm band. That's an indicator that you're in open loop.

My guess is that your car will be able to make the corrections in closed loop to cruise around at 14.7AFR. But when you get on it, you'll probably be lean since it doesn't apply the same amount of corrections to the fueling in open loop. So if you were tuned to be at 11.5AFR at WOT, with 2.5 more psi, you might be seeing 12.5-13.0 on your gauge, and that would be significantly leaner than you were tuned for. Your motor might be able to handle it, but I'd have them adjust the fuel table to keep you where you were tuned. But it could all be monitored by your gauge. If your AFRs are where they used to be, then the ECU is compensating correctly, and you don't have anything to worry about. If they're leaner, then that's what you need to address with an adjustment in the fuel tables.