Air/Fuel mix experts needed. Options

[malcolm2]

Hey hey... I need some suggestions. I went for a nice drive last nite. I have a AFR gauge that has not been working. But the PLX Devices system has a blue tooth transmitter so i can review the live data on my phone.

I was getting 10.5 A/F reading. It did jump to 12.5 as i went to neutral and coasted to a stop.

To start with, I was thinking i would pull the sensor and take a look, maybe clean it up and re-drive.

Any ideas about the 1st steps? The car seemed to run fine.

I will need to look them up here, but years ago I had a reply from, I believe, Mark Henry that gave me the following:

13.5-12.9 while accelerating of climbing
12-8-12.5 at WOT
16-17 going downhill or decelerating.

1911 cc L-Jet. I did tweek the AFM back in the day. 62,000 miles ago.

the link to the 5 page post from 2017

[malcolm2]

Yes, the reading is low. Question is how can i change them, short of the delicate AFM spring adjustment? Yes on the fuel mileage too.

1st i wanted to go over the sensor, wiring, and gauge to see if it was working. Maybe clean up the sensor or buy a new one from PLX Devices.

So looking for pointers on the AFR system and making FI adjustments.

[JamesM]

So looking for pointers on the AFR system and making FI adjustments.

On the AFM itself you can adjust the spring preload of the air meeting flap.

There is also a static position adjustment as well as the idle mixture screw.



Not sure what you can do as far as wiring other than testing the continuity and resistance readings of the sensors at the ECU connector.



The AFM adjustment is not a touchy as you might think, especially with a 50+ year old tired spring. You can mark the starting position and return it there if needed.

There is however the possibility that it was previously adjusted to get around a wear spot in the track, in which case you just need a new AFM.