06 chevy trailblazer highly modified
Eaton M112 supercharger ~5-6 psi
custom built intake
custom header/exhaust
yada yada
Ever since I installed the exhaust I've been having some lean spot issues on tip in and cruise. The exhaust yielded about an 17% change in peak air flow through the engine. The tip in can be fixed with VE tuning I'm sure but the cruise lean condition makes no sense. Somebody suggested to me it looks like a lean cruise programmed condition and I agree, low engine speed, generally light throttle, open loop and lean commanded lambda. I didn't notice it ever doing this before so I don't know why it started now.
Go to just after 6 minutes in the log, you see commanded lambda goes from stoich to 15.8. Fuel trims stop responding indicating open loop. I slowly increase throttle and it just gets leaner and leaner if you watch the wideband. Goes into the 17's and starts bucking. It doesn't jump out of this lean condition until the converter unlocks at 610 and the rpms jump.
How is this possible? There is no lean cruise options in the tune.
Any ideas or solutions to make it not do this?