I'm not sure if I imagined this, but IIRC my zeitronix read-out used to be 14.7 A/F when the car was idling. It would fluctuate up and down but would always stabilize. But the unit was always half-way covered and after awhile I stopped paying attention

However now that i've relocated the zeitronix unit to a more noticeable location, the screen reading shows that the car idles at 14.0 A/F and fluctuates around that point. At WOT, the A/F is incrementally lower also. In the past, 3rd gear at 7000 rpm was 12.2 A/F and now it is 11.8 A/F

At first I thought it might be the LCD screen, but I plugged the zeitronix unit directly to the labtop and it shows the same readings.

Can anyone with a WB02 confirm their A/F readings at idle? I was thinking that the ECU should automatically adjust for temperature changes.

 

At idle it should be 14.7.

 

At idle and anytime you are in closed loop, the AFR reading should oscillate around 14.7.

Does the zeitronix unit have auto-calibration for temperature, altitude, etc. ?

 

a calibration is needed.

 

No, the zeitronix doesn't have auto-calibration. They told me to send back the unit, lcd, and o2 sensor for testing. That is going to be a pain un-installing everything.

I'm wondering if the wbo2 went bad or if something is wrong with the ECU

 

mine hangs around 14.7 at idle....where did you place your wb o2? mine is in the test pipe

 

mine settles typically between 14.7-14.8 at idle after its warmed up. even though it may not have stuck, i have 8% fuel taken out at idle and up to 11% during partial throttle. i can see that return being a pain but definetely worth getting figured out.

 

i thought changing the part throttle settings won't do any good?

 

it will typically revert back but i left the settings and it is not doing any harm.

 

so what afr are you at with the current -8%?

and when you say "typically"...out of how many times will it go back...and how many times it won't?

 

hahaha, members from the chinese thread. Da(4) Jia(0) Hao(2)...

 

at 8% removed i see 14.7-14.8 at idle.

 

I have it right before the cat. It worked fine as long as I can remember. But for some reason now its only 14.7-14.8 cold start and then keeps dropping down to 13.8-14.0 warmed up.

Its annoying because WOT is reading pig rich, I datalogged 11.5 A/F ratio this morning. Zeitronix told me to pull the whole unit and send it back for testing. Thats going to be a big pain

 

then what are you running if you put it back to 0%?

 

have you checked your stock sensors? the wideband is problably reading right and your stock sensors are bad. then the car is going to adjust no matter what you do.

 

I used the OBD-II scanners, the car has no codes. The voltage and fuel trim "look" okay for the primary o2's (although i'm not sure how I can tell they went bad).

I purchased a new bosch wideband o2 to see if the sensor went bad. My gas mileage has been around 26.3 mpg, so I ruled out the o2 sensors going bad

 

i havent neutraled it out yet. i just used my harrison software and vafc2 to get my short term fuel trims as close to 0 as possible.

 

I must have used a bad batch of gas (or accidentally filled up on 87 octane).

The idle A/F is back to 14.7

I had to fill up the last two times previously at a no-name gas station during a business trip.

 

I notice a diff when a gas station is trying to pull off a scam selling 87 as 93 octane. My AF hangs around 14-14.2 on the cheap stuff and runs in the mid 12s under WOT. With 93 my car idles around 14.8-15.0 A/F. Under WOT I see 13.6:1 . I use PLX M300 that I've had for over a year, 155k mile Original 02 sensors also.

 

I idle at around 14.5-14.9:1 and at WOT, 13.5-14.3:1, but this after tuning.

 

Hmm... interesting. I don't have a probably usually because I only use Chevron gas. However when the A/F incident occured I had to fill up a few gallons because I was lost during a business trip.

My a/f under WOT was into the 11's at the time