I noticed that while datalogging the other night that my AFR would vary depending on if I was in 4wd vs 2wd and low boost vs high boost.

My AFR was highest in low boost (4.5psi) and in 2wd at 12.2. Put it into 4wd and the AFR drops into the 11s. Got to high boost and I see low 11s. High boost with 4wd and I am at high 10s. Is this consistant with what you see? If so which way do you tune yours? We tuned mine for 2wd in high boost since most freeway racing and from a roll stuff is what I'll be doing most often. My track times may suffer a bit due to being rich but at least I am safe on the street.

How are you doing it?

 

ok, I found out what you want to tune on. Because of the gear changes, the AFR will always change. We should tune the truck for 3rd gear. Which means we should lean it out some more because its running pig rich in third. The reason being is because thats the 1 to 1 gear. Now the only thing is the other two gears are going to be leaner of course, but it wont matter much because the loads are easier in those gears, so knock is not going to happen.

Rick

 

i tune mine for WOT at max boost in 4wd with the cut out open and look at the entire run. the a/f raito is prety flat. with the whipple the a/f ratio would change for each gear but with the turbo it seems to stay more consistant.

i keep it richer than 12.0 and if posiable shoot for 11.5-11.8 for as much of the run as i can. the problem is you get more air on a colder night and since the maf is maxed the computer doesn't know about it. if it is more than about 15deg cooler than when i tuned i will make sure i am loging to see how that is effecting my a/f ratio.

it is prety rich a lot of the time. take a warmer day with the cut out closed and i am at 11.0 a/f ratio. on the log below i sprayed for about 1 sec out of the hole. you can see the lean spike at the launch when it turns on. the rpm jet up due to wheel spin and the nitrous shuts off. then i grip and the rpm come down again turning the nitrous back on(2500-4500window switch). the perillies didn't hook so well. you can also see the converter lock at about 5000rpm in 2nd. i dont shift that high in 1st gear but all that jumping around and wheel spin messed up the shift point for some reason. i usualy **** at about 6200.

 

Glad to see other people using the FJO wideband. Its by far the best I think.

Yeah, we are going to shoot more towards leaning it out in third gear all around because right now on a cold night she would run about 10.5 straight through third gear.

Rick