General Lean Idle When Warm

[GSXDNA]

I just recently got a new long-block 9:1 2.3 stroker and a JMF SM IM. Turbo, injectors, ignition setup all the same as with my last setup/tune on my stock 2.0 w/ stock IM. I basically kept the tune the same, as I figured that'd be enough to just get the car drivable.

At cold start, car idles perfect at around 14.7 and 1,000 rpm. As soon as the engine gets to temp and it goes into closed loop, the AFR consistently goes between 16.5-18.0, and rpms cycle between 800-1,100 rpm. The O2 sensor is still cycling between .2 and .8 volts continuously (according to a general OBD-II monitor), while the AFR sits between 16.5-18. When I let the car cool off a bit then restart in open loop, AFR is dead on 14.7 again until it enters closed loop, then it goes lean again.

I'm replacing the O2 sensor now, but is there anything else that comes to mind as a likely cause for this? I'm working on getting a log to look at the fuel trims (my logging laptop crapped the bed). If my injector scaling were somehow way off, I'd expect cold start on open loop to be poor, too.

Any ideas?

 

[m_0ney_pit]

what MAF are you running?
do you have a way of changing your maf scaling?

The factory 2g maf scaling curve dips waaaay lean at 25 and 50 Hz and then sharply increases at 75Hz. Assuming you don't have any vaccum leaks your going to have to increase your injector deadtime and increase maf scaling at 25 and 50 Hz to get a better idle AFR. Your car is lean because its flowing more air now which is a good thing .

edit :Oh I just realized I didn't really answer your question haha...its ok at cold start because of startup enrichment and your car will naturally lean out as it gets warmer my car does the same thing.

 

[curt-s]

have you verified your pump is putting out the pressure to your fpr, or that your fpr is creating the same exact pressure at both cold and hot idle? you kept components, but a sudden failure might be to blame.

for instance, ever since my switch to SD, my fuelab and walbro 255 start out around 43.5 but after driving for 30-60mins, drops to 40 or lower (vac unplugged with engine running)
my entire afr map and closed loop goes about 10% lean.