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How lean is too lean while cruising

250 views 4 replies 4 participants last post by  TC SKATES  
#1 ·
Good morning guys. I’m having trouble finding an answer to this, but how lean is too lean while cruising. At certain RPMs/times I seem to be averaging 15.4 to 15.6 on the front O2 monitor. I noticed this specifically in sixth gear between 2300 and 2700 RPM.

Comm fuel final is right at 14.51 during this.

Running E85

Here is a log showing just that.

 
#2 ·
Who tuned the car? What did they say? That is a bit too lean, should be getting excellent HWY mileage though!😬
 
owns 2019 Subaru WRX STI Base FP Green Flex Fuel
#3 ·
i don't have anything constructive to add, other than that it is super weird that both af learning 1 and correction is 0. i saw in your other thread that it might be stuck in open loop? if you didn't know, you can add that to your monitor/log to check with: closed loop sw (on/off)

also, just wanted to say this website is so fucking cool lol i'm gonna go graph my own logs now
 
#4 ·
Yes, he should definitely check the OL/CL switch. I forgot about that.
 
owns 2019 Subaru WRX STI Base FP Green Flex Fuel
#5 ·
I had a similar problem when ny car would go into open loop while cruising. Turned out to be a vacuum leak that was present during the tune. Smoke test your car, and fix any leaks. If you see a big change in your trims further away from zero (usually the opposite direction) after you fix the leak, you need to be retuned. Your car can only compensate for a leak in closed loop, and under WOT it should be fuled appropriately, but theres that middle area under low throttle open loop thats not adjusted properly.

My leak was at the o ring of the oil filler tube