Lean partial throttle boost

[nissanman04]

My KA-T runs great at cruise and full throttle (near stoic at cruise, 12 or less AFR on full throttle boost). But if I only give it partial throttle and build around 4psi of boost, my AFRs are way to lean (in the 15s). I'm running a T28 setup on Nistune (480cc injectors, N60 MAF). What would be some possible causes of this? I don't have the factory O2 sensor hooked up at the moment since I'm still dialing in my injector multiplier for the new MAF and injectors, so the ECU is constantly in open loop. I would think that would rule out the ECU trying to run in closed loop mode under boost, but I could be wrong.

[480sx]

Sounds like you just need to adjust your fuel maps.

[bruinbear714]

My KA-T runs great at cruise and full throttle (near stoic at cruise, 12 or less AFR on full throttle boost). But if I only give it partial throttle and build around 4psi of boost, my AFRs are way to lean (in the 15s). I'm running a T28 setup on Nistune (480cc injectors, N60 MAF). What would be some possible causes of this? I don't have the factory O2 sensor hooked up at the moment since I'm still dialing in my injector multiplier for the new MAF and injectors, so the ECU is constantly in open loop. I would think that would rule out the ECU trying to run in closed loop mode under boost, but I could be wrong.

Don't have any experience with Nistune, but if you're leaning at partial boost then you need to adjust the fuel map.

BTW, what's the "lean" AFR at partial throttle boost?

[nissanman04]

That part of my fuel map is plenty rich, I assure you. It looks like it's an issue with the "injector response" map in Nistune. It doesn't allow the main map to be accessed at part throttle under 3200 rpm or so. I'm gonna play around with it later today.

http://ka-t.org/forums/viewtop...art=0

[nissanman04]

BTW, what's the "lean" AFR at partial throttle boost?

15-16

[eazye2000]

Yeah, add fuel to the lower section where 'load' isn't that much, and throttle position isn't that much either.

I don't know Nistune that well, but if you don't know how to tune it either, just find someone locally and explain to them what it's doing. They should just be able to adjust it somewhat for you. Preferably on a dyno.

How is the Nistune? I've been debating it for sometime.

[nissanman04]

Yeah, add fuel to the lower section where 'load' isn't that much, and throttle position isn't that much either.

I don't know Nistune that well, but if you don't know how to tune it either, just find someone locally and explain to them what it's doing. They should just be able to adjust it somewhat for you. Preferably on a dyno.

How is the Nistune? I've been debating it for sometime.

The main fuel map is not the problem, there is plenty of fuel being added. The other map that is causing the problems seems to limit injector pulse until a certain rpm/throttle position has been reached. I'm getting a tune this saturday, I just want to make sure the engine is running right so I don't waste my money.

Nistune is pretty good. I don't have any complaints, really. It's nice to be able to see everything that is going on with the engine and how changing certain parameters affect behavior in real time. I'd definitely recommend it.

[nissanman04]

The injector response map was the problem. I just lowered the value across the board and the AFRs are right where they should be, no matter what the TPS voltage.