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

[JamesM]

10.5 is way rich

Probably not impacting to much other than gas mileage, but I wouldnt want it there long term, thats rich enough to potentially be getting black smoke out the tail pipe on acceleration enrichment.


Ideally
~13.5 at idle
~12.8 full load

No reason to ever see anything richer than 12s. May be able to go leaner at idle if you have an ECU with the adjustment knob but 13.5 is usually around the strongest there.

light load/cruise is a lot less particular, not sure you are going to see anywhere near Mark Henrys targets with d-jet, light load/cruise usually winds up mid-high 13s. while leaning out this area is totally acceptable it can require additional ignition advance to avoid missfires which most of the stock setups dont give you. 14.7 is the HOTEST place you can run and you generally want to be either richer or leaner than that. Best for emissions, and totally fine on water cooled cars, but then that is why we dont have air cooled cars anymore.



EDIT: I missed that you are L-jet, you may be able to setup leaner cruise numbers.