Is it normal for AFR's to lean out in cold weather?
 

For Houston 40*f is cold now my 11:1 AFRs changed to 11.8-12 is this normal?

I'm runing V3 SMART.

This shouldn't happen. SMART should work to AFRs very close to the same level.

d

Totally normal and totally acceptable. Less overfueling is necessary when conditions get cold since the engine becomes less knock prone (due to subsantially lower charge temps). However, you can adjust the amount of fuel offset the SMART system puts in to make it compensive for temp changes to a greater or lesser extent. To make it run richer in colder temps, but bigger postive fuel offets in the upper half of the SMART fuel table :)

Shiv

Really? 0.5-0.8 points from ~72 to 40 degrees? My datalogs don't reflect this.

d

After the first to test runs I let the car sit for a while and went out again, AFRs got to 11.5-11.4. I presume this was due to the intake manifold getting heat soaked a bit. When I last checked my tune it was 80*f, afrs were 11s and the top of the cursor on the smart fuel table was at 0.

I have a big front mount that may be cooling too much in this 35-40* weather.
This is what SMART was trying to do.

https://www.evolutionm.net/forums/at...id=80089&stc=1

I'll try Shiv's suggestion and fatten up the correction starting at .5 interpolating up to top cell value.

SMART is so cool!