How exactly do you read this thing? I know it's not the most accurate gauge but the dinging back and forth threw me off at first. I thought just one section of the gauge would light up to show me how my mixture was balanced. Here's my usual readings.

In town driving (40mph)- dings back and forth slowly

Idle - dings back and forth slowly but sticks on lean more than rich

Interstate driving (70mph) - dings back and forth very fast and sometimes sticks right between stoich and rich

Under full boost - pinned in rich

I'm just asking this because I've noticed a nice coating of black exhaust soot on the inside of my exhaust tip which would indicate rich conditions. My fuel pressure at idle is right around 49 and under boost it's about 99 if I remember correctly. I know that's a bit richer than recommended but I'm scared to death of detonation. So how rich is too rich?

Yep, it sounds like you're just running a bit rich. The LED A/F gauge is a WOT gauge only. When you are idling and cruising, it just shows that your O2's are cycling like they should be. The only real time it's showing a reading is when you're at 100% throttle. If your gauge pegs at the last green LED, that means you're A/F is .95 (or higher).

Each light in the A/F gauge represents a different 02 voltage (or range of voltages). The instruction manual that came with the gauge has the voltage each light represents. If you need the numbers, I can post them as I still have my manual for the gauge. It may also be on the web somewhere if you do a search (maybe autometer's site also).

Let me know,
Kurt

Really? I don't remember seeing a manual with mine. I only remember mounting instructions.

Here's a good explanation of how the lights work(why they blink back and forth), and what the voltage values are in general for each light, on an unmodified Autometer AF gauge. http://gadgetseller.com/gauges/techinfo.htm


95 Eclipse RS : 5 speed
Jeep TB writeup - http://www.dimensia.com:81/jimbo/JeepTBfor2gnt.html

Sorry about that. I forgot to post this last night. It is the same information as what Metaljim posted.

LED Chart

Lean Range Four Red LED's (.050 to .249V)
Stoich Range Ten Yellow LED's (.250 to .749V)
Rich Range Six Green LED's (.750 to 1.000V)

One LED lights up for every 50mV of oxygen sensor output.

Hope this helps,
Kurt

Since we're on the A/F subject, does anyone have one of these gauges? Are they the same as the one's Corbin used to make?



What about the modified Autometer gauges they do? Can you tune with one of those too?