AFR VS Air Temperature

gavin · Post by **gavin** » Thu Aug 19, 2010 1:39 pm

Today i went on track with my car and the Air temp was around 17*C last week i set the AFR in WOT map to value around 12.5/13 the Air temp was around 27*C today the AFR was Very lean 16/15.3 is it posible to have that big difference by this 10*C temp difference? engine is N/A

Post by **robertisaar** » Thu Aug 19, 2010 2:44 pm

considering hotter air is less dense, and therefore has less oxygen, you should have been richer, not leaner...

it sounds like you have an air temp vs enrichment table or sccalar to mess with.

dfddfd2 · Post by **dfddfd2** » Fri Aug 20, 2010 4:12 am

He tuned at the higher temp., so when it cooled off 10ºC, it ran lean, which makes sense. The question I have is how is the fuel being metered? Is it MAF, speed/density (MAP). alpha/N?

Dave

gavin · Post by **gavin** » Fri Aug 20, 2010 12:34 pm

yes i have MAF,N/A-Naturally Aspirated (non turbo)

dfddfd2 · Post by **dfddfd2** » Fri Aug 20, 2010 12:46 pm

If the MAF is hot wire type, it should compensate for the IAT difference.

gavin · Post by **gavin** » Sat Aug 21, 2010 1:46 pm

it is hot wire MAF hole system is bosch motronic 3.1