ok. so when you guys datalog and tune based off the info your producing, do you guys tune in 3rd or 4th? I'd imagine it wouldn't matter what gear, simply because it's load based, correct? 10psi 1/2/3/4 would mean the same amount of load (of course first usually doesn't hit 10psi by redline.. but u get what i mean). so people always talk about dyno tuning in 4th gear.. i've also heard 3rd. but i've read several posts where people do it in 4th here. so I try to tune my car keeping it right around 11:1 afr at wot. but then I drive in third gear and nail it, when my revs start to get approx 5k, it starts leaning out... should i just tune based off 3rd and let 4th stay rich? I still think it's odd that it's not the same afr's....

also. having a small exhaust leak, would that richen up or lean out my afr gauge?
I think I may have a slight one... Need to take care of that... blah.
thanks,
Chase.

 

tune off 4th.

 

right. that's what i was doing.. but for whatever reason. i'd imagine that 3rd would run more rich if ANYTHING. but it leans out..blah.

 

You'll see readings in third prolly .1-.2 leaner. This is because there is less load on the engine.