something i have wondered about for weeks now and havent found an answer..
What kind of AFR shuld i be seeing while decelerating in gear?

i have noticed that when i let the engine slow the car at zero throttle i am seeing afr in the land of 15 at around 2500 - 3000 rpm, which scares the noobie in me
can anyone break down what kind of afr one should shoot for under those circumstances and what the risks are of running lean like that on decel. part of me says no big deal, an then the louder part kicks it in the nuts an says im an ******* whos gonna need a new engine. need insight.

 

if you are at zero throttle it does not really matter at all. In haltech you can actually have a decel fuel cut which will save you some mileage in the long run. You want to set that decel fuel cut to return fuel around 2k rpm so the car does not stall when you rev it/ let off/ put the clutch in.

 

Depends on what the engine wants. First, you're not going to hurt anything running the engine lean in an extremely low load situation like engine braking. You may notice, and it will be application dependent, that the engine will buck (miss) under drop throttle situations if the mixture is lean and/or the timing isn't right.

As mentioned fuel cut is an easy way to save a trivial amount of fuel and get the engine to decel very smoothly. No change for a misfire if there is no fuel in the chamber. You just need to get the return to fuel setup right, which shouldn't be too hard.

 

cool, that was sorta what the one voice was tellin me

the reason i was concerned fwiw was the thought that i would be heating up my combustion chambers while engine braking like that an then dumpin huge air n fuel in there comin off ramps and such. im gettin rediculous hot intake temps under boost as i have no hood scoop an stock TMIC, an didnt want to be adding to the potential detonation by running lean like that. wanted a second opinion, thanks guys.

as an after thought can i set one cell to run rich at a certain rpm so as to be an ******* an pop flames but only when wanted?

since ive got a thread goin no point in startin another since its sorta related. with regards to intake temps i see close to 70 degrees celcius on hot days on boost, and i can hear mad popcorn when i stop at lights afterwards. is that pinging? just the turbo an manifold and IC cooling off? the two gerbils that run the thing coughing? i havent got a knock sensor and haltech wouldnt care if i did. would adjusting the air temperature fuel correction map to not lean out as much at high temperatures be a reasonable means of controlling this for the time being?

 

Those are some high IAT

 

im running the stock TMIC and i get as high as 160F/70C on 12 psi. I have no detonationi problems though, im running 10.5 AFR and about 18 adv/10 split at 12 psi

dont worry about running lean in high vacuum, shouldnt cause knocking, but timing too advanced will. what is your timing when it is knocking?

 

i dont hear anything while actually driving but thats prolly the exhaust an stereos fault, the popcorn i hear at idle is at 3 degrees accordin to the haltech with timing properly zeroed