So, I've been trying to fine tune my cruising afr's. In closed loop it fluctuates around 14.3:1 instead of 14.7:1. I've tried zeroing out the open loop thresholds, drove around and logged, made a couple changes and got the car to run great around 15.0-14.7, put the open loop thresholds back and 14.3 seems to still be the center point.

Any idea how to get the car to run a little leaner at least 14.7?

 

Nope only way is to force open loop, unless you have a zeitronix that you can wire into the ecu and change stoich to whatever you want...

 

If it runs 14.7-15 in open then it should be 14.7 in closed (really should be 14.7 in closed no matter what), but I mean with fuel trims being close to 0. How are your trims btw? Also, you feel like just leaving it open loop in the cruise area? that's one way to get leaner cruise..

 

Yeah, that's what I was afraid of.


My Fuel trims are reading -4.5 LTFT mid and -2.1 LTFT low. o2 feedback (STFT) reads zero. I'm wondering if the trims are even logging correctly. They never seem to be any different.

 

o2 feedback should always be changing, that's what the ECU is doing at the very moment to keep the AFR as close to 14.7 as possible. LTFT's update every 4 minutes or so, so it's normal that they don't move very much.

 

any idea why it's not logging correctly? it just shows zero

 

Must mean you front o2 isn't working for some reason. Do you have any CELs?

 

Hmmm. No CELs.

 

Did you for some reason disable the rear O2 in periphery bits? The trims also wont read anything if you are in open loop....

 

I found an o2 simulator wired inline on the rear o2 tucked under my center console. I removed it and in the process found about 4-5 feet of egt gauge wire, and a random wire connected to the front o2. After removing all that garbage. The Fuel trims are reading. I love cleaning up someone elses mess.

Tephra mod options
rear o2 sim is enabled

Rear o2 Heater is Enabled

ECU Periphery0 (FAA)
rear o2 is 1

ECU Periphery4 (FEA)
P0140 rear o2 no ACT is 1

anything else I should look into?