Random AFRs
 

I have been trying to tune my setup and have noticed that randomly my AFRs will be super high (leaning out) At first I thought maybe I was over-compensating on my fuel map, so I stopped tuning and just started driving it. It has always stayed consistent on the drive, but every time I start the car it runs different. There are drives where it will go so rich that the car will bog down, and others where it is so lean I don't dare take it into boost. Has anyone seen this before and have an idea of what could be causing it? I can grab some logs, but I don't see anything different on them other than the afrs, so I don't know how helpful they are

1.8L
speeduino
FM2 Turbo kit
new FlowForce 640cc
new Walbro 190lph fuel pump

Could be hardware, could be software, could be the tune. Post a tune and log file. Try to dig through the log file yourself first. When it leans out, is there an enrichment that's altering the fuel output by a significant amount, especially when comparing to somewhere in the log where the AFR was behaving correctly? Is your IAT sensor mounted somewhere that it won't heat soak? Does this issue only happen soon after starting the car and have you tuned startup enrichment and warmup enrichment?

Thanks for the tips, I'll run some good logs today and see if I can find anything out of the ordinary.. The issue is always happening at operating temperature (~198) and I have my IAT is in the reccomended placement by Flyin Miata, on the backside of the intake next to the passenger headlight

make sure the gasket between your exhaust manifold and downpipe is good. Also the exhaust manifold gasket itself. itll suck a little bit of external air and your wideband will read lean but under driving theres enough exhaust pressure to not have that problem. i had this issue and made tunning annoying. you can usually tell because itll read lean but actuall drive good.

This is super helpful. Thanks for the tip, I'll check it out.