I just realized today I've been running lean under part throttle. Hondata is in closed loop as well. It was a little like this before, but more so now that I switched back to an OEM o2 from a bosch. The car will bog when taking off in first and it makes it hard to drive. I'm getting insane gas mileage this tank and I've been boosting the same as before. Gas mileage has gone up almost 10 miles per gallon since switching the o2. I've already gone 194 miles and the needle is right about half way. Which would be about 38.8 miles per gallon I bumped the fuel pressure up about 3-4psi and it should be ok until I can make it to the tuner. So how harmful is it? I should have realized it before
Now that I think about it, I've been hearing my walbro more now too. I hope it's not taking a dump, it's only 3 months old.. Thanks.

Nate

 

If you're at part throttle and in closed loop... yr ECU aims for 14.7 A/F ratio... nothing to worry there.
Start to worry if you're in open loop and lean out

 

Yes.. If you had something screwie with your o2 sensor before the ecu might not have been going into closed loop.. But now that it is thats why your getting the good gas mileage..

 

I didn't even get this good of gas mileage when the motor was completely stock with the stock ecu Like 4MPG less than this tank now babying it with the stock motor. And I've been boosting plenty on this tank.. Just by raising the fuel pressure it doesn't bog from 0-25% throttle anymore. Wouldn't that mean it's lean?

 

The only time you need to worry about running lean at part throttle is if your part throttle boosting. If your not in boost then its fine.