lart951

Is it normal to run a bit richer on hot weather? I was driving today and I noticed my WB gauge showing 11:2 at wot. When i dialed my car a/f ratio was a cool day.


TIA

Lart

ehall

air is less dense the warmer it gets. If you set it on a cool day, and it is now almost 100F there, there should be a difference. How much? Not sure. Mine does it too.

eclou

Cold weather means denser air and leaner AFR's. An older BMWCCA and SSCA racer/builder told me he always tunes the car for the coldest tracks he will run in, to prevent burning a valve or worse.

lart951

Thanks Elliot glad you are sober today and can have a reasonable conversation

lart951

Well I am glad I tuned my car in a cold day.

danny951

Would a 951 with a MAF sensor and correct chips be able to correct for the denser air on a cold day and supply more fuel to the mixture?

special tool

Yes the Vitesse system on my car compensates 100%.
This has been seen on at least 50 datalogs.

danny951

that's what I figured, but just wanted to verify.

lart951

My Lindsey racing digital MAF is has the air temp. sensor but I guess is not working?

eospeed

My car is running about 11.3 on a 100° day at 20psi ,I tunned it on a 85° day an it was about 11.8-12.0


Erik

Ian Carr

maybe the difference in quality between vitesse and lindsey??

Jake951

I've also noticed richer A/F ratios in hot weather. I originally tuned my A/F ratios in summer weather. I then found that in New England winter conditions I was running too lean under WOT. I retuned the A/F for cold weather but now I run too rich in the summer.

That's one reason I've decided to try a Vitesse MAF setup, which is supposed to maintain constant A/F ratios, independent of temperature. I guess the special Vitesse "MAF chip" may have something to do with this. My Vitesse kit should be arriving shortly!

lart951

I should of got a vitesse

hally

Sensor is most likely OK i would say, if you are using AFM chips with a MAF sensor then your tuning is going to be more easily upset by changes in temp and boost.

njim3

Quote:
Originally Posted by lart951
My Lindsey racing digital MAF is has the air temp. sensor but I guess is not working?


I have LR maf and Mafterburner, i tuned my car when it was 65° and AFR is 13.8-14.8
nothing much changes when i run at 100°. The only differnece is little rich at idle when it gets hot
it is around 12.8.-13.5@idle.