PUR NRG

I'm getting what I think are inconsistent results.

Using the stock map my idle is way rich. Acrid white fumes come out the exhaust even after it's warmed up and the RPM dips down below 800, surges up to 1000 and goes back to 900 for a while before repeating the cycle.

Idle hovers around 20Hg so I thought I'd try changing just that value. Bumping it down two increments to 2.29 didn't really help. Anything below that and starting the car required feathering the gas.

#1 I then tried bumping everything from 20 - 5Hg down two increments from stock (2.29, 2.48, 2.81, 3.05). That seemed to work just great, with AFRs around 13.3.

#2 I then tried bringing 10 and 5Hg back to stock levels (2.81, 3.05) to see what would happen. Despite enrichening those values the AFR now averaged 14.0 which seemed too high. RPMs stayed fairly constant near 880.

#3 Next I changed 20 and 15Hg up one, bringing them one increment down from stock (2.33, 2.52). Now AFRs averaged 13.6. RPMs were still fairly constant so I stopped here for now.

So here's my question: Why did dropping all four values by two result in 13.3AFR, whereas only reducing 20 and 15 result in 14.0AFRs? I can understand why AFR went richer going from #2 to #3, but going from #1 to #2 and getting leaner doesn't make sense.

In all instances I was stopped and measured idle AFRs for at least twenty seconds for each setting.

adrian-1

What was your AFR's at before the tweaking? Mine was around 11.2;
The highest I could get it was 12.8 but it kept shutting off. Currently it's around 12.0 but I'd like it around 13.5,

I removed my wideband O2 sensor and calibrated it just to make sure my readings were correct. Also smells rich.

I don't remember the exact settings but they're much lower than yours.

PUR NRG

AFRs were below 12.05 but I don't know by how much. After a day of driving around with setting #3 my idle AFRs are now around 12.8. I don't know why they have gone down but I plan to check again tonight to see where they're at. The fumes are dramatically better but you can still smell unburnt fuel. However I'm afraid going lower will mean I'll have more starting issues. I don't know if changing plugs will help but I'm hopeful.

I am getting random engine shutoff at "cold" water temps so I'll have to tweak the water map.

upgradesRX

i dont know what temps you were making the idle adjustments at but you may want to make sure you are around 80 degrees before adjusting them(that should be operating temp) also if your concerned about the start up fuel you can control that through the water maps for cold starts. if you are adjusting the idle map when the car is still cold you will get different readings from different temps as the water map will be supplying fuel along with the settings you have at 25 and 20hg.

adrian-1

Yeah, the car was warm each time. It's 82C and above where the extra fuel added is 0%.