Car Running Lean
 

https://datazap.me/u/altezza3363/log...0&data=3-19-24
(End of log has a 4th gear pull)

Hi all, I was monitoring the A/F ratio as I recently put something new on my car and found the car is running lean. At 25%-50% throttle the A/F will drop to 10.8~11.5, as I increased the throttle the A/F would raise back up to 12.x. The car is pulling strong but I believe it's too lean? What could be possible cause of this?
The bypass valve actuator was recently replaced and I just installed a radium PCV catch can. Not sure if related but the car has bad battery. Although it starts normally, it feels like stalling when rolling toward a stop sign.

Mod List:
Edelbrock Supercharger
Delicious Tuning Dbox
Catless header, catted front pipe, catback
Radium Catch Can (PCV)
Straight E85
Remote tuned

Thank you for your help!

11 afr is not lean thats rich



For a SC car on petrol idle 14.7, cruise arround 14, mild acceleration 13 heavy acceleraton 12 possibly into high 11 on petrol is normal expected afr.




Lower number is richer higher number is leaner.


For logs post them up to www.datazap.me

Hey Steve. Is a car OK if AFR's at correct (~14.7) under throttle by fuel trims are way off (-22%)?

Thanks for the response. My initial post wasn't very clear.
But the situation was at mild throttle the car is running quite rich, and as I increased the throttle to 100% or close to 100% then it starts running lean, at high 12.x, in some range it even passed 13.
In the end of the log, you can see the actual AFR dropped and then raised back up as the throttle increased.
https://datazap.me/u/altezza3363/log...og=0&data=7-19

22% trims means the ecu is applying 22% correction to attmpt to hit the afr target. High trims usualy mean someting is wrong , intake or exhaust leak, maf scaling error injectpr scaling error etc.

Or like me a broken wire to the maf.

I had the delicious tuning dbox, but how did you confirm that the MAF went bad?

Sent from my Pixel 3 XL using Tapatalk

It wasn't the maf it was the solder connection. I relocated the maf to a straighter section of the intercooler piping and had to lengthen the wires.

Start simple - do a smoke test to see if there are any exhaust leaks. If you've got a leak at the header flange, it'll easily make the trims you're seeing.

Smoke test will save you a lot of time!!!

My tuner just sent me a map based on the log. I will try that map first and if that's not the problem I will check for exhaust leak. I was suspecting a leak before as my car smells VERY ethanol.