Originally posted by KingpinSVT:
Sorry I was in the mountains all weekend.

First, all pulls in 4th, of course.

Second, the graph from this summer at sealevel shoes me at a solid 12:1 AFR. Very consistently so too. Without making any changes except to my location, my AFR shoots up to about 14:1. We havent made any changes to fuel, AFR, anything like that. The AFR also didnt seem to change with the tunes either. It was almost exactly the same each time.

I dont know why its so lean. I feel like it has to be related to altitude. At lower alt. it was so steady at 12:1. Now its steady at 14:1. Like I said, I havent touched a thing besides timing so its got to be something that the car isnt correcting on its own.

BTW, thanks for the help Mark. Feel free to step in!

I'll try to get some of the graphs scanned in tonight.



Did you recalibrate the sensor in each location before you climbed to altitude? If you mount the O2 sensor in the exhaust and then drive around without recalibration, things like air density will greatly affect it.
It balances the measured O2 against what it picks up in the atmosphere.
If outside pressure goes up and nothing else changes in the fuel ratio, and there is no calibration, then it will read more rich as the ratio of O2/O2 outside/inside is higher.
IF you lower the pressure then the O2/O2 outside to inside will be lower and read leaner.

Former owner of '99 CSVT - Silver #222/2760 356/334 wHP/TQ at 10psi on pump gas! See My Mods '05 Volvo S40 Turbo 5 AWD with 6spd, Passion Red '06 Mazda5 Touring, 5spd,MTX, Black