biggles

I am planning to dyno my car in an effort to see whether I am running lean at WOT, feels as if I am after shut down. What should be my A/F reading at WOT? The dyno readings that I have seen here appear to have A/F readings mainly in the 13's, which from my 951 days would be rather lean.

biggles

Geoffrey

Your 951 is a turbocharged car, so you need extra fuel to remove heat from the engine's combusiton process and will run rich of peak power. The 964 makes peak power at 13.0-13.2:1 which is rich enough to cool the engine. A stock 964 runs very rich in the midrange near peak torque at about 12.0:1 and will lean out to mid 13.5:1 on the upper RPM band.

As these cars age, the AFM wiper sometimes goes bad an affects the AFR. This shows up as a significantly different AFR curve than required, or as a flat spot in the range of the sensor and is displayed as a lean spike during a pull.

biggles

Thanks for the knowledge, Geoffrey. My concern is upon shut down, I am getting some gremlins in the engine, not major but do not want to ignore. Not sure if its bad gas, Shell 93 Octane always, but since I am running Steve W 93 octane chip, no cat and G-pipe, I just want to be sure that A/F is within range.

biggles